@conference {41510, title = {Effect of precalving feeding level on the milk production of grazing dairy cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {227-231}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Fifty-two multiparous dairy cows were allocated to four treatments with an apparent daily intake of 5.8, 8.9, 10.0 or 11.2 kg dry matter (DM)/cow/day of pasture for 27{\textpm}9.6 days precalving. This equated to 1.3, 2.0. 2.3 and 2.6\% of liveweight (not including the conceptus weight; LW). Following calving, all cows were fed generously on pasture. Daily milk yields were recorded postcalving and fat, protein and lactose concentrations determined on 2 days each week for 5 weeks. Blood was sampled 17 days precalving, on the day of calving and on days 1, 2, 3, 4, 7, 14, 28 and 35 postcalving. Precalving plasma concentrations of insulin-like growth factor-1 (IGF-1) increased (P<0.05) quadratically with increasing pasture intake. Concentrations of growth hormone declined (P<0.05) linearly and concentrations of non- esterified fatty acids declined (P<0.001) quadratically with increasing DM intake. Plasma concentrations of these metabolites postcalving showed no effect of precalving feeding. Level of feeding precalving did not affect milk yield or the yield of fat, protein or lactose in milk, but postcalving DM intake was negatively (P<0.1) related to precalving DMI. These results indicate that 0.93 MJ metabolisable energy/kg LW0.75 was required in the final three weeks of gestation to maintain cow energy balance. }, issn = {1176-5283}, author = {Roche JR and Kay JK and Kolver ES and Aspin PW and Lee J and Sugar B and Napper AR} } @conference {41400, title = {The effects of insulin on the milk production of pasture-fed Jersey cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {35-39}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {The aim of this experiment was to determine the effects of insulin on milk protein production in lactating, pasturefed dairy cows. Five lactating rumen-fistulated Jersey cows were subjected to a hyperinsulinaemic euglycaemic clamp (HEC) with and without an abomasal infusion of casein (310g/d) in a two period cross-over design experiment. The HEC significantly reduced milk yield in the control cows compared to casein-infused cows (9.9 {\textpm} 0.5 vs 13.2 {\textpm} 0.5 kg/d, P<0.001). Milk protein yield was significantly higher in the casein-infused cows compared to the control cows (482 {\textpm} 16 vs 421 {\textpm} 16 g/d, P<0.05). The HEC significantly reduced milk protein yield in the control cows compared to casein-infused cows (311 {\textpm} 16 vs 459 {\textpm} 16 g/d, P<0.001). The use of the HEC technique in pasture-fed cows did not result in the milk protein response reported in concentrate-fed cows. }, issn = {1176-5283}, author = {Back PJ and MacKenzie DDS and Davis SR and Harris PM and Lee J} } @conference {41379, title = {Improved nutritional quality of animal products through manipulations of trace element and calcium status}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {325-329}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {

Research on the requirements and metabolism of trace elements in grazing livestock is revealing new ways in which the nutritional status of people might be improved. Our understanding of how to manage the mineral status of cattle and sheep can create additional impact through enhancing the quality and value of milk and meat. For example, by optimising the familiar selenium and iodine supplementation strategies used to prevent deficiencies and maintain animal mineral requirements, we can tailor the element content of the resulting animal products. Simple Se and I supplementation produces commensurate increases in milk and meat, but the concentrations of calcium and iron are not so easily manipulated, so other smarter strategies are called for. For these four nutritionally essential elements, maximum concentration and bioavailability to humans is affected by age of animal, stage of lactation, plus element chemical form and distribution among the milk and meat fractions.

}, issn = {1176-5283}, author = {Knowles SO and Lee J} } @conference {41305, title = {Increased milk lactic acid concentration is an early indicator of mastitis}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {22-23}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {The cost of mastitis to the dairy industry in NZ is substantial, with economic losses accruing from antibiotic costs, acute and chronic milk yield losses and reduced longevity of susceptible cows. Early detection and treatment of mastitis is a critical factor in reducing the severity of the infection and tissue damage within the udder (Douglas et al., 1997). However, increases in labour productivity are reducing contact time with cows, making early detection of mastitis increasingly difficult. In particular, the development of robotic milking equipment has highlighted the need for remote detection of mastitis. Apart from visual examination of fore-milk, somatic cell count (SCC) is used as the standard marker of milk quality. An increase in bulk milk SCC or a high SCC at herd test is used to diagnose new infections. However, one of the most widely used methods for cow-side or automated in-line testing for mastitis is the detection of changes in electrical conductivity of milk. This approach has several problems, not least of which is the limited accuracy of the method (see Woolford et al., 1998) and the relatively high cost of sensors (claws). The following study was undertaken as part of a screen of a number of potential markers in milk which could be used to indicate mastitis {\textellipsis} }, issn = {1176-5283}, author = {Farr VC and Prosser CG and Nicholas GD and Lee J and Hart AL and Davis SR} } @conference {41378, title = {Predicting copper status of cattle remains an engima}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {319-324}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {

Data are presented from several studies carried out by AgResearch and Massey University describing scenarios that affect the Cu status of grazing cattle. In all these studies, complex interactions between Cu, Fe, Mo and S make it difficult to predict Cu status. Increasing pasture Mo reduced percent absorption of dietary Cu in sheep by half (from 4.6\% down to 2.6\%). In contrast, the Cu kinetics in cattle could not be similarly simplified, so more sophisticated modelling calculations need to be applied. Even with moderate Mo intake (i.e. from pasture 0.8 mg Mo/kg DM), liver Cu content was quickly depleted in the cattle, reaching a low but stable level of 8 mg Cu/kg DM that appears to be a Mo-insensitive liver Cu store. In other trials, various Cu supplementation strategies have produced considerable but unexpected responses in liver Cu content. The risks and benefits of using liver Cu concentrations as an index of Cu status, and whether a multi-variable approach using tissue biomarkers, animal physiology, diet composition, and time of exposure is what is required to accurately predict the future Cu status for cattle are discussed.

}, issn = {1176-5283}, author = {Lee J and Knowles SO and West DM} } @conference {41271, title = {Effects of insulin on amino acid uptake by the mammary gland of the pasture-fed lactating ruminant}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {61}, year = {2001}, month = {Jan}, pages = {144-147}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Twelve lactating ewes housed indoors were allocated to one of two treatment groups (hyperinsulinaemic euglycaemic clamp (HEC) or control) in a randomised block design experiment. Mammary amino acid uptake from plasma and utilisation for milk protein synthesis was measured during the fourth day of the HEC using the arterio-venous concentration difference (A-V) technique. There was no change in milk protein output during the HEC (P>0.05). The HEC induced a significant decrease in arterial concentrations of all essential amino acids (EAA) except for histidine and an increase in the extraction efficiency of isoleucine (HEC, 61 {\textpm} 3\% vs. control, 52 {\textpm} 3\%, P<0.05) and leucine (HEC, 64 {\textpm} 3\% vs. control, 53 {\textpm} 3\%, P<0.05). There was no significant change in extraction efficiency of other EAA or mammary blood flow. The ratio of amino acid uptake from plasma to output in milk protein suggested deficits in uptake for some EAA in both treatments, especially histidine. These results indicate that the mammary gland can adapt to a changing arterial supply of amino acids to maintain milk protein output by increasing extraction efficiency and/or a greater reliance on amino acids supplied by erythrocytes and/or plasma peptides. }, issn = {1176-5283}, author = {Back PJ and Davis SR and MacKenzie DDS and Harris PM and Roy NC and Lee J} } @conference {41298, title = {y-glutamyl transpeptidase and amino acid transport for milk protein production in vivo}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {61}, year = {2001}, month = {Jan}, pages = {244-247}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Activity of the enzyme g-glutamyl transpeptidase (g-GT) (EC 2.3.2.2) a putative facilitator of amino acid (AA) transport in the mammary gland, increases before lactation and decreases at weaning, suggesting a role in AA transport for milk protein synthesis. The effect of g-GT inhibition by acivicin and supply of cyst(e)ine from N-acetylcysteine (NAC) on mammary AA uptake and milk production was studied in lactating goats. NAC increased (P<0.05) arterial supply of some AA but did not increase arterio-venous difference as a percentage of arterial supply (extraction \%) and did not alter milk protein yield. Acivicin decreased (P<0.05) milk protein yield but this effect was not found when NAC was administered in combination with acivicin. This indicates that NAC, by indirectly enhancing intracellular cysteine, countered the effect of acivicin inhibition, suggesting a role for g-GT in supply of cysteine for milk protein synthesis. }, issn = {1176-5283}, author = {Johnston SL and Roy NC and Davis SR and Tweedie JW and Kitson KE and Lee J} } @conference {41074, title = {Amino acid utilisation by the mammary gland: Whole blood versus plasma free amino acid pools}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {59}, year = {1999}, month = {Jan}, pages = {62-65}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Utilisation of amino acids (AA) by the mammary gland of dairy cows has been studied in order to understand the responses in milk protein production to alterations in nutrient supply. One approach has been the use of balance studies, in which the amount of AA taken up from the blood by the mammary gland is compared with their respective output in milk protein(s). Although it is generally accepted that the free AA pool in blood is the major precursor for milk protein synthesis, there are differences when plasma or whole blood arterio-venous differences (A-V) are used to measure the uptake of AA by the mammary gland. Arterial and venous blood samples were obtained at 2 h intervals from cows fed fresh pasture over two 12-h sampling periods. The samples were subdivided into whole blood (WB) and plasma (P) and analysed for free AA concentrations, which were used to estimate amino acid concentrations in the erythrocyte. There were no significant differences in the A-V calculated from WB or P for the majority of AA. Plasma A-V was significantly higher than WB for threonine (13.9 vs 8.9 nmol/g blood) whilst WB A-V was higher than P for isoleucine (26.9 vs 23.3 nmol/g blood) and tyrosine (11.8 vs 10.3 nmol/g blood). Assuming the differences in A-V between WB and P can be attributed to AA exchange with the red blood cell (RBC), significant (t<0.01) exchange from RBC to the mammary gland occurred for only isoleucine (15\% of WB A-V) and tyrosine (14\% of WB A-V). These results indicate that plasma AA concentrations are valid measures of the immediate free amino acid pool available for uptake by the mammary gland. }, issn = {1176-5283}, author = {Pacheco-Rios D and McNabb WC and Treloar BP and Barry TN and Lee J} } @conference {41073, title = {Lack of effect of short term chromium supplementation in lactating Jersey cows}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {59}, year = {1999}, month = {Jan}, pages = {58-61}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The responses of dairy cattle to chromium (Cr) supplementation reported in the literature suggest that it has the potential to reduce the incidence of both mastitis and ketosis. The effect of Cr supplementation of pasture fed dairy cows in early lactation was studied. Ten lactating Jersey cows fitted with rumen fistula were infused with either Cr-yeast (n=4), casein (n=3) or buffer only (controls; n=3) directly into the abomasum. All cows were subjected to a hyperinsulinaemic euglycaemic clamp. Preliminary results show that there was no effect of Cr supplementation on milk yield, cortisol and b-hydroxy butyrate concentrations and somatic cell counts. }, issn = {1176-5283}, author = {Back PJ and Lee J and MacKenzie DDS and Davis SR and Harris PM} } @conference {41068, title = {Relationship between wool sulphur concentration and wool characteristics}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {59}, year = {1999}, month = {Jan}, pages = {43-45}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {It is well established that naturally occurring wool sulphur concentration is lower in high wool-producing sheep, however little is known of the relationship between wool sulphur concentration and wool fibre characteristics. Mid-side wool samples were collected from ewe hoggets differing in lamb wool sulphur concentration. Wool from hoggets, which had lower wool sulphur concentrations as lambs, had longer staple lengths, were higher yielding and had lower loose wool bulk values. There was no relationship between wool sulphur concentration and mean fibre diameter or colour. An increase in length should have a positive effect on the price of wool, especially for second shear crossbred wools. At present the price premium for bulk is poorly defined, but is unlikely to have a significant impact on the value of these wools. These findings suggest that selecting animals for low lamb wool sulphur concentration will, if anything, positively affect the per kilo price of wool produced. }, issn = {1176-5283}, author = {Kenyon PR and Sherlock RG and Lee J and Blair HT} } @conference {41030, title = {Amylin causes hypocalcaemia in lactating goats - Brief Communication}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {209-210}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Amylin is a 37-amino acid peptide, structurally related to calcitonin-gene-related peptide (CGRP), adrenomedullin and calcitonin (CT). It is co-secreted with insulin from the pancreatic {\ss}-cell. There is increasing evidence from rodent models that amylin may play an important role in the regulation of mineral metabolism, particularly Ca (Cooper, 1997). However, such a role has never been investigated in a ruminant model. The aim of this study was, therefore, to investigate a role for amylin in the regulation of Ca and metabolism of other minerals in lactating goats.}, issn = {1176-5283}, author = {Min SH and Farr VC and Lee J and Cooper GJS and Davis SR} } @conference {41000, title = {Arterio-venous differences of amino acids across the mammary gland of cows fed fresh pasture at two levels of dry matter intake}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {98-101}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Four cows housed indoors in metabolism stalls were used in a cross-over experiment to test the effect of two levels of dry matter intake on amino acid metabolism during early lactation (October). Fresh ryegrass/white clover pasture was offered ad libitum or at 75\% of the ad libitum intake during 2 experimental periods. Concentrations of essential amino acids (EAA) in arterial and mammary venous plasma were determined as indicators of the uptake and utilisation of individual AA for milk protein synthesis in the mammary gland. The relative concentrations of free EAA (expressed as \% of total EAA) of lysine, tyrosine, leucine, phenylalanine, methionine, tryptophan and histidine were lower in arterial plasma than those in the milk protein, suggesting these as limiting EAA. Using extraction rates of plasma as an indicator of potentially limiting amino acids, leucine, lysine and methionine appeared, in that order, as the most limiting amino acids in the ad libitum animals. In the intake restricted animals, the order of limitation appeared to change to methionine, lysine and leucine. }, issn = {1176-5283}, author = {Pacheco-Rios D and McNabb WC and Cridland S and Barry TN and Lee J} } @conference {41051, title = {The determination of sulphur in wool using near infrared reflectance spectrometry}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {281-283}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {A method and calibration for estimating sulphur (S) concentration in wool using near infrared reflectance spectrometry (NIRS) is described. The NIRS measurements were calibrated against wet chemistry determinations of wool S (R{\texttwosuperior} = 0.81, relative standard error {\textpm} 3.7\%, n=339). The first derivative spectra with 14 partial least squares terms gave the lowest cross-validation error for the calibration using an independent set of wool samples (R{\texttwosuperior} = 0.78, cross-validation error {\textpm} 0.11, n=66, mean 2.88 g S/100g wool). The correlation spectrum gave a series of approximately equally weighted peaks from about 1300 - 2400 nm, corresponding to -NH stretching and bending modes (protein). The -SH absorption between 1736 and 1746 nm could also be identified. Although scouring differences contributed to marked spectral differences in the visible region (yellowness was related to the first 3 principal component scores) these did not affect the overall S calibration. Uses for the calibration include wool S as an indicator of lifetime wool production, changes in wool composition in response to supplemented cysteine or energy intake, and the relationship between wool S and wool characteristics. }, issn = {1176-5283}, author = {Corson DC and Martin W and Lee J} } @conference {41027, title = {Effect of zinc oxide treatment for facial eczema on the copper status of Romney sheep grazing ryegrass pastures}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {199-201}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The copper (Cu) status of grazing Romney sheep was monitored following treatment with zinc oxide (ZnO). In a series of experiments sheep of various ages were treated with ZnO as either an oral drench weekly for one year, or as an intraruminal controlled release bolus (Time CapsuleTM , AgResearch) once (on day 0) or twice (on day 0 and 40), in two consecutive years. Measurements of Cu status included Cu concentrations in liver, kidney and muscle in all animals, and liver metallothionein (MT) in sheep dosed with ZnO orally. Drenching of two-year old wethers with 12 g ZnO/week for 52 weeks did not significantly change Cu liver concentration compared to untreated control animals (mean {\textpm} SD, 1.93 {\textpm} 0.88 and 1.67 {\textpm} 0.87mmol cu/kg FW, respectively). However, administering a single 42-day intraruminal ZnO bolus to six-month old lambs resulted in decreased liver Cu concentrations after 40 days (0.96 {\textpm} 0.06 compared to 1.33 {\textpm} 0.07 mmol Cu/kg FW in controls; P<0.001). When lambs which were growing at 100g/day were treated with a second ZnO bolus and evaluated after an additional 40 days, Cu liver concentrations were reduced by a further 20\% but this change was not statistically significant (P=0.07). The variable effects of different forms of Zn treatment on liver Cu concentration are discussed in terms of duration of the dose, age of the animals, DM intake, initial Cu pool size in the liver, and Cu/Zn-binding MT. Under most conditions the benefits of ZnO as an effective facial eczema control are likely to outweigh any short term reduction in liver Cu. }, issn = {1176-5283}, author = {Rounce JR and Knowles SO and Grace ND and Lee J} } @conference {41025, title = {The effects of a cation-anion balanced diet on calcium and phosphorus metabolism in growing lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {192-194}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {During the past decade, there has been renewed interest and research in the role of the dietary cation-anion balance (DCAB) in controlling Ca and P homeostasis. Two diets differing in DCAB (either high DCAB, 250 meq/kg DM, or low DCAB, -100 meq/kg DM) were fed to 10 Romney lambs. Feeding low DCAB decreased urine pH by 2.0 pH units; from 8.2 (SE=0.45) to 6.2 (SE=0.50), indicative of the anticipated changes in the ionic balance associated with alterations in the dietary CAB. Plasma concentrations of Ca and P, and whole-body Ca and P balance (intake-excretion) were similar for both groups of sheep. Reducing the dietary CAB caused a 7-fold increase in the urinary excretion of Ca (low DCAB 0.75 g/day vs high DCAB 0.11 g/day; P=0.001).The apparent absorption of Ca in the low DCAB and high DCAB groups were 1.6 and 1.3 g/day, respectively, although there was no significant difference between the two groups. These data indicate that lowering the DCAB increases urinary excretion of Ca of growing lambs without affecting Ca balance due to an alteration in the movement of Ca to and from bone. Similar changes in Ca absorption and utilisation have been observed in dairy cows, suggesting that the growing lamb is a suitable model for future studies in the regulation of Ca homeostasis in dairy cattle. }, issn = {1176-5283}, author = {Wilson KL and Min S and Revell DK and Lee J and MacKenzie DDS and Cottam YH and Davis SR} } @conference {41026, title = {Variation in copper metabolism between two flocks of Romney sheep in response to increasing dietary intake of copper}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {195-198}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Differences in the Cu status of two flocks of Romney lambs were observed which suggest that lines of sheep having distinct Cu metabolism have been identified. As part of a larger study relating Cu intake to Cu status of grazing lambs, changes in concentrations of Cu in liver, plasma and other tissues, and in erythrocyte Cu/Zn superoxide dismutase (SOD) were monitored for 176 days in two flocks of 50 sheep. The animals grazed on ten experimental paddocks treated with 0, 0.4 or 4 kg Cu/ha which resulted in mean pasture herbage Cu concentrations of 8 (Control), 13 (Low), and 41 (High) mg Cu/kg DM. At the start of the experiment these lambs, sourced from two Wairoa farms, had markedly different liver Cu reserves (1270 v 190 mmol Cu/kg FW, flocks H and L respectively) which could not be attributed to Cu supplementation. This difference between flocks was maintained throughout the 176 day study for sheep grazed on control pastures, through day 99 for sheep on the low pastures, and for 51 days in sheep on the high paddocks. High copper intakes increased liver Cu concentrations to as much as 4800 mmol (300 mg) Cu/kg liver FW after 99 days, with no signs of chronic Cu toxicity. Initial flock differences in liver Mo concentration (14.7 v 20.6 mmol Mo/kg FW, n=10, P<0.05) disappeared by day 51. The first measured SOD activity (day 51) in flock H was 17\% greater than that of flock L (1600 v 1370 U/g Hb, n=21, P<0.01) and this flock difference was maintained through day 142 and day 99 for sheep grazing control and low pastures, respectively. SOD activity was found to be a reasonable predictor of liver Cu stores only in sheep having low to moderate Cu intake. Had the differences in initial liver Cu concentration and in blood Cu/Zn SOD activity of the two flocks been merely a reflection of the Cu and Mo status of their respective Wairoa farms, the disparity would have been expected to diminish much more quickly than was observed in this study. Factors controlling Cu metabolism are heritable. Trials selecting for differences between flocks in liver Cu concentration are needed to establish whether these flocks are genetically distinct in the way they metabolise Cu. }, issn = {1176-5283}, author = {Knowles SO and Rounce JR and Grace ND and Lee J} } @conference {40932, title = {Metabolic changes in the mammary gland of sheep prior to, and at, parturition.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {57}, year = {1997}, month = {Jan}, pages = {209-211}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Four sheep fitted with an indwelling catheter in the femoral artery and a transit time ultrasonic flow probe around the left pudendal artery (supplying the mammary gland) were used to quantitate changes in mammary blood flow (MBF) in late pregnancy and lactation, and to determine the extraction of glucose and oxygen by the mammary gland. Mammary vein blood samples were collected by venipuncture. Considerable variation existed in the pattern of change in MBF between individual sheep. In two animals, MBF through the pudic artery fitted with the flow probe doubled to 600 mL/min on the day of lambing (DL), while in the other two sheep, MBF varied little in response to lambing. Possible explanations for this difference between individuals are discussed. Glucose extraction trebled on DL from 6.0 to 18.7\% (P<0.01) and remained high during lactation in relation to milk output. Oxygen extraction by the mammary gland peaked during the last week of pregnancy (at 45.7\%) and during lactation it was related linearly to milk output. }, issn = {1176-5283}, author = {Revell DK and Harris PM and Cottam YH and Reynolds GW and Lee J} } @conference {40776, title = {Utilisation of methionine by the mammary gland of the lactating goat}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {56}, year = {1996}, month = {Jan}, pages = {53-57}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The goat milk protein, a-lactalbumin, contains no methionine residues, hence if 35S label is supplied to the gland in the form of labelled methionine only, the appearance of 35S in a-lactalbumin gives a measure of transsulphuration of methionine to cysteine within the gland. Two lactating Saanen goats were surgically modified with catheters implanted in the mammary milk vein, femoral and external pudic mammary artery, and jugular vein to enable infusion of 35S-methionine, into either the whole body (jugular) or directly into the gland, and repetitive blood sampling. Specific radioactivity of methionine in the blood and milk proteins was determined at hourly intervals for 9 hours. Radioactivity of 35S was determined in a-lactalbumin when 35S-methionine was supplied directly to the gland via the mammary artery, but could not be detected when supplied via the jugular vein. Analysis of mammary tissue from the latter experiment did however show the appearance of 35S label in the intracellular cysteine pool which was derived from methionine. Both approaches suggested that transsulphuration within the gland, although small, may be important especially when supply of methionine to the gland is high. The fractional extraction of plasma methionine by the gland for two goats was 46.4}, issn = {1176-5283}, author = {Lee J and Treloar BP and Sinclair BR and Prosser CG and Davis SR and Harris PM} } @conference {40703, title = {Metabolic changes of cadmium and zinc in kidney and liver tissue during foetal development in Romney and Merino sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {176-178}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Diseases affecting mucosal surfaces, especially gastrointestinal disorders, cause high mortality rates in young domestic livestock. Hyperimmune milk products, using milk secretions from ruminants immunised systemically with enteric pathogens, have been shown to confer passive immunity against such disorders but the results are variable. To study the type and titre of immunoglobulin (Ig) classes produced in milk secretions after immunisation with gut pathogens, we have developed ELISAs for the estimation of ovine IgG and IgA antibodies directed against E. coli. Utilising an indirect ELISAs technique, the method involved coating antigen onto microtitre plates then sequential addition of test sample dilutions (containing primary antibody), anti-class-specific antibody and anti- species horse radish peroxidase labelled antibody. Colorimetric end point detection employed 3, 3}, issn = {1176-5283}, author = {Rounce JR and Lee J and Treloar BP and Grace ND and Sinclair BR} } @conference {40704, title = {Response of trace element concentrations in plasma of sheep to chronic infusion of a recombinant variant of IGF-1}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {179-182}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Bio-ijmpedance (BI) is the opposition of biological tissues to the flow of an alternating low electrical current. Tissue BI is quantitatively inversely related with tissue hydrational status. Several reproductive events of importance in the management of the cow are characterised by changes in fluid content and electrolyte concentration of the genital tissues; these changes can be detected and quantified by genital tissue BI monitoring. The objective of this presentation is to review existing and potential applications of monitoring genital tissue BI in cows as aids to cattle reproductive management. The main application is genital BI monitoring to determine the optimal insemination time. It is based on the fact that intravaginal and vulvar tissue BI decline ca 10-30\% during the peri-ovulatory stage of the ovarian cycle. Genital BI measurements can also be used to detect pending calving as well as post partum reproductive disorders: vulvar BI, measured with chronically implanted electrodes, declines ca 15 d before, and remains low until calving. During ca 40d post-calving, vulvar BI increases gradually and stabilises at about the time of resumption of ovarian luteal cyclicity. Intravaginal BI during the first 4-6 weeks post-calving is significantly lower in cows with reproductive disorders than in }, issn = {1176-5283}, author = {Lee J and Rounce JR and Hocking-Edwards JE and Harris PM} } @conference {40556, title = {Cadmium accumulation in liver and kidney of sheep grazing ryegrass/white clover pastures}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {31-34}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Pastures growing on soils fertilised with phosphatic fertilisers accumulate cadmium (Cd) in their plant tops in proportion to substrate concentrations. Sheep grazing pastures absorb some of this Cd. To quantify the rate with which Cd is accumulated in sheep tissue, three replicated 0.4 ha blocks were fertilised with either 333 kg/ha of single superphosphate only (control) or amended with CdSO4 to give 274g Cd/ha (high-Cd), and set stocked with 10, three months old Romney wether lambs. Cadmium (Cd) concentrations were determined in liver, kidney, proximal duodenal and skeletal muscle tissue of sheep, ingesting either (means {\textpm} s.e.) 266{\textpm}22 (control) or 746{\textpm}58 (high-Cd) ug CD/day from three to six months or 290{\textpm}21 and 721{\textpm}72 ug Cd/day over six to eighteen months. Cadmium concentrations in kidney and liver tissue increased markedly over the first three months: 0.042{\textpm}0.006 to 0.32{\textpm}0.03 (Control) and 0.57{\textpm}0.04 (high-Cd) ug Cd/g fresh tissue, and 0.04{\textpm}0.006 to 0.12{\textpm}0.02 (Control) and 0.31{\textpm}0.06 (high-Cd) ug Cd/g fresh tissue, for kidney and liver respectively. Although total Cd content continued to increase, as organ size increased, over the next 12 months daily accumulation rates in both tissues were much lower compared with those over the first three months. For example, daily Cd accumulation in kidney decreased from 0.25{\textpm}0.002 to 0.06{\textpm}0.01 and 0.47{\textpm}0.04 to 0.32{\textpm}0.05 (ugCd/d) for sheep from the control and high-Cd pastures respectively. Total Cd content in kidney and liver combined accounted for approximately 0.25\% of total Cd ingested by sheep age three to six months but this significantly decreased to 0.1\% in sheep age six to eighteen months. At higher Cd intakes increased metallothionein protein synthesis in kidney and liver tissue enabled animals to be more efficient in sequestering Cd. This resulted in reduced accumulation of Cd in muscle tissue of sheep on the high- Cd pastures (2.0{\textpm}0.04 and 5.0{\textpm}0.08 ng Cd/g) compared with those grazing the control pasture (4.0{\textpm}0.6 and 14{\textpm}5 ng Cd/g) in animals from the first and second periods respectively. The results from this study show that it is the first few months after weaning that fastest uptake into kidney occurs and therefore strategies to reduce Cd absorption and subsequent accumulation, e.g. by increasing zinc in the diet, should focus on young animals. }, issn = {1176-5283}, author = {Lee J and Grace ND and Rounce JR} } @conference {40584, title = {The effect of whole body cysteine supplementation on cysteine utilization by the skin of a well-fed sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {139-142}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Research, in both New Zealand and Australia, is being directed towards enhancing the sulphur amino acid supply of sheep by either plant or animal modification. This study investigated the effects of such improved systeine supply in well-fed sheep on both whole body and skin metabolism of cysteine.. The level of cysteine supplementation chosen (2g/d) represented about a 50\% increase in absorbed cysteine. Cysteine was supplied by jugular infusion to avoid loss during gut absorption. At this level of cysteine supplementation a preliminary trial on sheep fed either 700 g or 1250 g lucerne chaff showed no significant effect on wool production but a significant increase in wool sulfur (S) concentration over a one month period of treatment. In a second trial, two groups of five, 40kg, cryptorchid Romney sheep were offered 1200 g/d of lucerne chaff and one group was supplemented with 2g/d cysteine for five days prior to measurement, with the other group receiving saline only. Cysteine supplementation increased whole body cysteine utilization (irreversible loss of 35S-cysteine) from 4.7 {\textpm} 0.4 to 6.4 {\textpm} 0.3 g/d, while appearance of 35S-cysteine in the oxidation pool increased by 37\%. Cysteine supplementation resulted in an increase in circulating cysteine concentration (33.8 {\textpm} 5.6 to 51.1 {\textpm} 12.0 {\textmu}M) but blood flow to the skin patch (measured by dye dilution) was reduced from 0.29 {\textpm} 0.03 to 0.21 {\textpm} 0.02ml. min-1.g-1 skin. Hence the cysteine flux through the skin (blood flow times concentration) was unchanged. Nevertheless uptake of 35S-cysteine by the skin increased with supplementation from 12.8 {\textpm} 2.7 to 22.8 {\textpm} 2.7\%, resulting in a significant increase in skin utilization of cysteine for protein synthesis. The results suggest that enhancing cysteine supply within the sheep does not proportionately improve cysteine availability for protein synthesis. Instead a large proportion of the extra supply is oxidised. Additionally, although enhanced whole body cysteine supply does not improve skin cysteine supply (or flux), increased arterial cysteine concentration appears to stimulate skin cysteine transport into cells so that increased cysteine utilization for protein synthesis is still achieved. }, issn = {1176-5283}, author = {Harris PM and Lee J and Sinclair BR and Treloar BP} } @conference {40575, title = {The utilisation of whole body cysteine by the mammary gland of the lactating goat}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {103-106}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Three lactating Saanen goats weighing 55-71 kg, producing 1.2-3.6 kg milk/day and fed ad libitum concentrates and hay, were infused via a jugular catheter with 35S-cysteine (35S-Cys) at 9.3 mCi/min for 9 hours. Blood samples were taken hourly and mammary tissue biopsied terminally. Concentrations and specific radioactivities (SRA) of cysteine (Cys) and glutathione (GSH) were determined in whole blood, plasma and mammary tissue. Mean arterial concentrations (nmoles/g{\textpm}SE) of Cys and GSH in whole blood, plasma and red blood cells were: 71{\textpm}7, 79{\textpm}9 and 19{\textpm}8; and 823{\textpm}30, 1.6{\textpm}01 and 3426{\textpm}124 respectively. Arterial SRA in whole blood at plateau (7-9h) of 35S-Cys (352{\textpm}13 dpm/nmole) was higher than that for GSH (5.9{\textpm}0.7 dpm/nmole). However the difference between intracellular SRA for Cys and GSH in mammary gland tissue was much less (231{\textpm}23 vs 146{\textpm}13 dpm/nmole). Total uptake of Cys by one half of the mammary gland was 0.5{\textpm}0.2 g/day. Whole body irreversible loss rate of Cys was 7.3{\textpm}0.7 g/day, giving a percentage utilisation of whole body Cys by the mammary gland of 13.6{\textpm}4.3. }, issn = {1176-5283}, author = {Knutson RJ and Lee J and Davis SR and Harris PM and MacKenzie DDS and McCutcheon SN} } @conference {40501, title = {Intake and excretion of cadmium in sheep fed fresh herbage}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {251-254}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {In two trials, ewes (n=16 per group) that were potential recipients for embryo transfer grazed on a high oestrogenic red clover (Pawera), a newly developed low oestrogenic red clover (G27) and Ryegrass-White clover (Control) pastures. The ewes grazed the respective pastures during 12 days of intravaginal sponge insertion, and for a further 23 days after induced oestrus. The mean (}, issn = {1176-5283}, author = {Grace ND and Rounce JR and Lee J} } @conference {40423, title = {The effect of condensed tannin containing diets on whole body amino acid utilisation in Romney sheep: consequences for wool growth}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {243-246}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Fleece production, fibre characteristics and spring liveweight in adult alpaca, tui and cria farmed in the South Island are reported. The shearing and fibre classing techniques are also described. Liveweight at shearing was 63.9kg, 65.7kg and 67.8kg for 1989, 1990 and 1991 respectively which is markedly increased from the South American records. The latter two years are significantly (p<0.05) higher than the initial year (1989) following importation. Clean fleece weight was similar in the latter two years, averaging 1.8 kg, but fibre diameter was significantly (p<0.05) coarser from 25.2 }, issn = {1176-5283}, author = {Lee J and Harris PM and Sinclair BR and Treloar BP} } @conference {40432, title = {Wool growth and elemental composition}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {281-284}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Six Merino wethers were used to graze six box-grown genotypes of subterranean clover in a Latin square design. Each animal was offered 2 replicates of each genotype and permitted to graze 70\% of the sward on offer. The amount eaten was recorded at each grazing and video recordings were used to record each sheep{\textquoteright}s grazing behaviour. There were genotype differences in the rate of intake of fresh feed (g/min) with Clare (79.3 g/min) being eaten faster than the other genotypes while Trikkala (67.1 g/min) was eaten faster than both Geraldton (53.0 g/min) and Dinninup (54.9 g/min). Similarly bite rate and dry matter (DM) per bite (bite weight) were significantly related to genotype. With Dinninup the rate of intake and DM per bite were less than expected from the measured sward characteristics while differences in sward height accounted for most of the differences recorded with Clare (20 cm tall) and Geraldton (8 cm tall). The results indicate differences in the intake response of sheep to different genotypes of subterranean clover. Possible reasons for these differences are discussed.}, issn = {1176-5283}, author = {Lee J and Bray AR and Grace ND} } @conference {40305, title = {Effect of high and sustained zinc supplements on trace element metabolism in sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {51}, year = {1991}, month = {Jan}, pages = {173-178}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Alpha-lactalbumin (alpha-lac) is a component of the enzyme complex lactose synthetase which plays a key role in the regulation of lactose synthesis and milk water secretion. Ribozyme mediated manipulation of alpha-lac expression should enable more precise elucidation of its physiological significance and may lead to the development of transgenic animals. Five ribozymes and controls targeting different regions of the alpha-sac gene have been synthesised and cloned. In vitro ribozyme analysis involved the incubation of in vitro transcribed alpha- lac and ribozyme RNA. The rate of ribozyme cleavage in vitro was influenced by temperature, MgC1 2 concentration, length of antisense flanking sequences and region of the alpha-lac gene targeted. In vivo ribozyme analysis was carried out in the T7/vaccinia expression system using C127I mouse mammary cells. This system utilises the powerful bacteriophage T7 RNA polymerase which is expressed when cells are infected with a recombinant vaccina virus. Gene constructs, cloned into vaccina plasmids downstream from a T7 promoter are transfected into the cells and are transcribed and translated at very high levels. Using this system we have identified that ribozymes that targeted exposed stem loops and the 3{\textquoteright} end of the gene down regulated the level of alpha-lac RNA to 10-20\% of the controls. Similar reductions in expression of alpha-lac protein were observed for these key ribozymes, but in addition a full length antisense was equally as effective. The expression of these ribozymes in transgenic mice will enable evaluation of their effectiveness to influence lactose synthesis and milk water secretion. }, issn = {1176-5283}, author = {Lee J and Grace ND and Martell S} } @conference {40348, title = {Wool sulphur concentration in fleeceweight-selected and control Romney hoggets}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {51}, year = {1991}, month = {Jan}, pages = {395-400}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Dairy and beef cows (n=349) which had calved at least two sets of twins were identified in farmers{\textquoteright} herds in 1982-85. Their calving performance is summarised here, and an experimental herd was founded from a sample of them. The calvings of 11 high twinning-rate dairy herds identified from this publicity are also summarised. Repeat-twinning cows were from factory-supply dairy herds (66\%), town-supply dairy herds (10\%), beef herds (21\%) and house cows (2\%). The twin calving rate in factory-supply survey herds with Friesians was 2.6\%, greater than the national average. There were, on average, 2.44 twin or triplet sets per cow. Of all the multiple births, 1.3\% were triplet sets. Data on sex ratios of calves from the twinning cows suggested that probably all their twins were the result of multiple ovulations. Perinatal calf survival rates averaged 86\%, with 80\% of sets having both calves surviving; 21\% of twin calvings were associated with a retained placenta, and 18\% of twin calvings were assisted. Mean ages of cows at first and later twin calvings were also summarised. The 11 {\textquoteright}elite{\textquoteright} herds averaged a 4.1\% twin calving rate (21 000 records), with 16\% of cows calving at least one set of twins. Subsequent twin calving frequencies were summarised. The 69 foundation experimental cows averaged 2.39 twin sets and a 50\% twin calving rate/year at purchase, and subsequently (1983-89) a twin calving rate of 10.3\% (18 sets/174 calvings) compared with controls at 0.8\% (1/121). }, issn = {1176-5283}, author = {Sun YX and Koolaard JP and Blair HT and Lee J and McCutcheon SN} } @conference {40225, title = {Effect of increasing Fe intake on the Fe and Cu content of tissues in grazing sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {265-268}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The fleeces of 30,000 ewe hoggets from 12 Merino flocks were sampled and the mean fibre diameter and clean fleece weight were measured in 1987 and 1988 and the best were selected to establish a superfine joint venture (SFJV) flock of 307 breeding ewes. The breeding objective is to achieve mean fibre diameter below 17um in the adult fleece while maintaining fleece weight and live weight. Concomitantly, a random control flock (RC) of 101 ewes was constituted from the flocks screened. Both flocks are farmed on MAF Technology{\textquoteright}s high country station at Tara Hills, Omarama. The screened SFJV flock has significantly lower live weight (p<0.01), greasy fleece weight (p0.05), loose wool bulk (p<0.001) and mean fibre diameter by 2 um (p<0.001). Staple length (P<0.001), staple crimp (P<0.05) and yield (P<0.05) were significantly higher for the SFJV flock compared with the RC flock. Wool returns of SFJV flock were $81.78/hd and $107/hd vs $62.21/hd and $47.00/hd for RC flock in 1988 and 1989 shearing respectively }, issn = {1176-5283}, author = {Grace ND and Lee J} } @conference {40199, title = {Nutritional partitioning of growth for productive gain}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {81-90}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Artificial insemination (AI) is widely used throughout New Zealand dairy herds because it is convenient and allows herd owners to utilise semen from intensively selected genetically superior sires. The future focus of AI use will be to synchronise oestrus in maiden heifers and cows to further concentrate seasonal calving patterns. There will also be continued use of progesterone-based treatments to stimulate ovarian activity in anoestrous cows and to increase pregnancy rates in inseminated cows. Aspects of behaviour and marked seasonality in red deer and fallow deer currently present challenges to increasing the use of AI and controlled breeding in these species. It would be preferable to have fawning/calving in spring instead of summer, with or without the use of AI. However, the semen production of stags is best from 4 weeks after the onset of the induced or normal rut. This potentially increases the dependence on deep frozen semen and increases the need for the uterine deposition of sperm to increase sire coverage and achieve satisfactory pregnancy rates. Controlled use of hormones will produce altered calving/fawning dates and developing semen collection/processing techniques will increase the use of AI in deer. }, issn = {1176-5283}, author = {Harris PM and Waghorn GC and Lee J} }