@article {3672, title = {TECHNICAL NOTE: Emissions improbable: how inappropriate use of the Global Livestock Environmental Assessment Model (GLEAM) can overestimate the emissions associated with dairy-production chains}, journal = {New Zealand Journal of Animal Science and Production}, volume = {81}, year = {2021}, month = {01/2022}, pages = {164-167}, address = {Online}, abstract = {In this paper we calculate the key differences between emissions estimates made using the Food and Agricultural Organisation of the United Nations (FAO) Global Livestock Environmental Assessment Model (GLEAM) and the New Zealand-specific analysis performed for the New Zealand Greenhouse Gas Inventory and the Fonterra Farm Gate Milk life-cycle analysis (LCA) that provides a proxy for all New Zealand milk production. We discovered that a wide range of factors can be responsible for more than a doubling of emissions calculated using GLEAM compared with emissions calculated using New Zealand-specific data. Such inappropriate use of GLEAM and the resulting conclusions have been used to undermine the efficiency of New Zealand production systems in publications such as Emissions Impossible. Keywords: Life cycle analysis; modelling; dairy processing}, issn = {1176-5283}, author = {Fletcher AJ and Sneddon NW and Hill JP} } @article {3672, title = {Genetic parameters, breed and heterosis effects for conformation scores in cows milked once a day}, journal = {New Zealand Journal of Animal Science and Production}, volume = {80}, year = {2020}, month = {09/2020}, pages = {51-54}, address = {Online}, abstract = {The use of conformation traits to aid selection for functional cows becomes more important as once-a-day (OAD) milking for whole or part season becomes more common. In 2013, Massey University Dairy 1 farm transitioned their mixed-breed herd milked twice-a-day (TAD) to an OAD spring-calving system. All cows on the farm were scored for 14 inspector-scored type traits and four farmer-scored traits, for a total of 1,617 lactation records over seven seasons (2013-2019, 168 to 258 cows per year). Genetic parameters, breed and heterosis effects were obtained from an animal model that included the fixed effects of year of scoring and cow age at scoring, and the covariates of proportion Holstein-Friesian, heterosis between Holstein-Friesian and Jersey, and the random effects of permanent environment of cow and random additive genetic effect of animal. Stature and live weight were found to have the greatest heritability estimates (0.46 and 0.41 respectively), while leg angle and body condition score had the lowest (0.03 and 0.04 respectively). Breed had a significant effect on all type scores, with heterosis also having significant effects; this is an important consideration with the increasing importance of type scores for cows in OAD milking systems. Jersey cows had greater front udder and udder support scores than did Holstein-Friesians (P<0.05), while Holstein-Friesians had greater stature and liveweight scores (P<0.05). From this study, genetic selection for improved udder conformation would see beneficial gains over time, whilst body condition score is heritable, would not be similarly improved. Keywords: Traits other than production; once-a-day milking; genetic parameters}, issn = {1176-5283}, author = {Sneddon NW and Donaghy DJ and Lopez-villalobos N} } @article {3672, title = {Association of bacterial contamination of colostrum with passive immunity and growth rates in dairy heifer calves}, journal = {New Zealand Journal of Animal Science and Production}, volume = {79}, year = {2019}, month = {07/2019}, pages = {149-152}, address = {Palmerston North}, abstract = {Failure of passive transfer of immunity in calves is associated with poor-quality colostrum, determined by Immunoglobulin G (IgG) concentration. Another quality problem of colostrum is bacterial contamination, which can impair IgG absorption by the calf. Thirty-five samples from daily pooled first-milking colostrum collected over a period of six weeks were tested for IgG concentration and bacterial contamination. Seventeen of 35 first-milking colostrum samples (49\%) had bacterial counts above a 100,000 CFU/ml threshold. Twenty-nine of the 35 pooled colostrum samples were fed to 63 newborn heifer calves, of which 12 (41\%) had bacterial loads above 100,000 CFU/ml and were fed to 36 calves. Only eight samples (28\%) had Brix values >22\% and five samples (17\%) fed to nine calves met the criteria of low bacterial load and high Brix (>22\%). Twelve of the 63 calves (19\%) had serum IgG concentrations <10 mg/ml so were classified as having failure of passive transfer, of which 10 of these calves were offered colostrum with high bacterial counts. However, there was no association of level of bacterial contamination with subsequent growth. There were no differences in serum IgG concentrations of calves which were fed colostrum that exceeded the quality threshold and those that were not. Calves with greater serum IgG concentrations grew faster (P<0.05). }, issn = {1176-5283}, author = {Back PJ and Hickson RE and Sneddon NW and Coleman LW and Laven RA} } @article {3672, title = {Regression of traits-other-than-production phenotypes for cows milked once a day on estimated breeding values obtained from cows milked twice a day}, journal = {New Zealand Journal of Animal Science and Production}, volume = {79}, year = {2019}, month = {07/2019}, pages = {140-143}, address = {Palmerston North}, abstract = {The use of traits other than production (TOP) to aid selection for conformation fit-for-purpose offspring becomes more important as once-a-day (OAD) milking for whole or part season becomes more common. In 2013 Massey University Dairy 1 farm transitioned their mixed-breed herd milked twice a day (TAD) to an OAD spring-calving system. All cows on the farm were scored for 14 inspector TOP traits and four farmer-scored traits for a total of 1,163 records over five seasons (168 to 254 cows per year). The scores were adjusted for age of the cow and season. The adjusted phenotypes for all cows for each trait were then regressed on their corresponding nationally-produced TAD estimated breeding values (EBV), which had been calculated without using these phenotypes. The four farmer-scored traits had the lowest relationships with EBV. Estimates of regression coefficients near one were observed for the udder traits (udder support, rear udder, front teats, udder overall), dairy conformation and body capacity. This supports the use of national EBVs in OAD herds derived mostly from records on daughters in TAD herds. }, issn = {1176-5283}, author = {Sneddon NW and Lopez-villalobos N and Garrick DJ and Rocha JF and Donaghy DJ} } @article {3672, title = {Genetic parameters for milk urea concentration and milk traits in New Zealand grazing dairy cattle}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {56-61}, address = {Lincoln}, abstract = {The aim of this study was to estimate genetic parameters for milk urea (MU), yields of milk (MY), fat (FY), crude protein (CPY) and lactose (LY), concentrations of fat (FP), crude protein (CPP) and lactose (LP) and efficiency of crude protein utilisation (ECPU) in grazing dairy cows. Data consisted of 1284 herd-test records of milk traits and MU from 468 mixed-breed cows in two herds. Univariate and bivariate repeatability animal models were used to estimate heritabilities (h2) and genetic (rG) and phenotypic (rP) correlations among the traits. Estimates of h2 for MU and ECPU were 0.24 and 0.11, whereas h2 estimates for MY, FY, CPY and LY ranged from 0.10 to 0.20. Estimates of h2 for FP, CPP and LP were 0.37, 0.59 and 0.19, respectively. The estimates of rP for MU with other traits were near zero. The rG of MU with MY (0.38), and of MU with LY (0.31) were positive and significant (P<0.01) whereas the rG of MU with FP (-0.80), CPP (-0.66) and LP (-0.76) were negative and significant (P<0.01). The rG between MU and ECPU was -0.09. These estimates of genetic parameters can be used to predict genetic responses to selection for reduction of MU.}, issn = {1176-5283}, author = {Lopez-villalobos N and CorreaLuna M and Burke JL and Sneddon NW and Schultz MM and Donaghy DJ and Kemp PD} } @conference {3672, title = {Brief Communication: Managing liveweight gain of Holstein-Friesian, Jersey and Holstein- Friesian-Jersey crossbred heifer calves}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {69-71}, address = {Rotorua}, abstract = {Large numbers of replacement heifers are not meeting target live weights in New Zealand (McNaughton \& Lopdell 2012; Handcock et al. 2016) which has implications for future milk production, fertility and subsequent longevity in the herd (Van Amburgh \& Tikofsky 2001; McNaughton \& Lopdell 2013). Undergrown heifers can lead to an overall decline in a herd{\textquoteright}s reproductive performance and milk production (McNaughton \& Lopdell 2012). McNaughton and Lopdell (2013) reported that for every 1\% increase in the percentage of live weight attained, heifers produced approximately 23 litres of extra milk during their first two lactations. As such, heifer growth, particularly post-weaning growth, has been identified as an area requiring greater attention from farmers to improve cow performance. There are established breed liveweight targets as well as liveweight targets based on an individual animals genetic potential and the growth of individual animals and groups can be monitored using programmes such as Livestock Improvement Corporation{\textquoteright}s MINDA Weights{\texttrademark} herd-recording software. However, while growth targets are commonly used, in many cases, being {\textquoteleft}on-target{\textquoteright} is based on a mob average, resulting in a proportion of animals below target live weight....}, issn = {1176-5283}, author = {Back PJ and Hickson RE and Sneddon NW and Coleman LW and Laven RA} } @conference {3672, title = {Comparison of health and reproductive treatments over three seasons for once-a-day and twice-a-day milking herds}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {211-215}, address = {Rotorua}, abstract = {Once-a-day (OAD) milking has been increasing in popularity in New Zealand, while housing cows is being advocated as one means of minimising environmental impacts of dairying. The present study aimed to investigate health treatments under four different farming systems: OAD, and three twice-a-day (TAD) systems (housed, standard and commercial). There were health records from 377 cows milked OAD and 878 cows milked TAD, over the dairy seasons 2013-14, 2014-15 and 2015-16. Data were analysed assuming binomial distributions for the dependent variables with a generalised linear model that included the effects of season, system (OAD, TAD systems), breed and lactation number. In 2014-15, cows milked OAD were treated less often for mas-titis than cows milked TAD (12\% and 25\% respectively; P<0.05). Cows milked OAD had fewer reproductive treatments compared to cows milked TAD (standard) in 2014-15 and 2015-16 (1\% vs 39\% and 2\% vs 40\% respectively; P<0.01). These results support the advice to farmers that milking OAD does not have a major impact on the risk of mastitis but may provide benefits in terms of reproductive performance. In addition, cows milked TAD (housed) had 13\% of the cows treated for lameness compared to 7\% of cows milked TAD (standard) (P<0.01). }, issn = {1176-5283}, author = {Van Der Spek P and Sneddon NW and Lopez-Villalobos N and Donaghy DJ and Laven RA and Mueller KR and Amoore J and Doohan H} } @conference {3672, title = {Random regression curves for body condition score and live weight from cows in two different dairy systems over three seasons}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {72-76}, address = {Rotorua}, abstract = {As housing is adopted to minimise the environmental impacts of farming activities in New Zealand, it becomes important to investigate the impact of this on the body condition of cows as a predictor of animal welfare. The P21 project undertaken at Massey University{\textquoteright}s Dairy 4 recorded the body condition score (BCS) and live weight (LW) of cows either under duration-controlled grazing during sensitive periods ({\textquoteleft}housed{\textquoteright}) or standard feed-pad ({\textquoteleft}standard{\textquoteright}) system. A total of 10,350 BCS records and 10,950 LW records were available from 978 cows over three dairy seasons (2013-14 to 2015-16). Random regression curves for daily BCS and LW were modelled using a 5th order Legendre polynomial. Data were analysed with a linear model, which included the effects of system, season, the system by season interaction and proportion of breeds (Jersey and Friesian), and cow age fitted as co-variants. The BCS was greater in 2014-15 than in either 2013-14 or 2015-16, (4.48 vs 4.33 and 4.28, respectively). The BCS of the housed and standard cows were significantly different (P <0.01) in 2013-14 and 2015-16. Housed cows were heavier than standard cows in both 2013-14 and 2014-15. These results indicate that housing of cows could improve on their BCS and LW. }, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Donaghy DJ} } @conference {3672, title = {BRIEF COMMUNICATION: Do different grazing strategies affect pre-weaning calf growth rates?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {119-121}, address = {Adelaide}, abstract = {Rearing replacement heifer calves is a labour-intensive and expensive component of dairy systems (Drackley 2008). Large numbers of replacement heifers are not meeting target live weights in New Zealand (McNaughton \& Lopdell 2012) which has implications for future milk production, fertility and subsequent longevity in the herd (Van Amburgh \& Tikofsky 2001). This paper reports results from the second year of a long-term experiment being conducted at Massey University that examines the impact of colostral status and liveweight gain of heifer calves fed different diets on subsequent milk production, fertility and longevity in the herd. Previous work (Cardoso et al. 2015) demonstrated no difference in pre-weaning liveweight gain of calves fed different levels of milk. The calves in that study ate surprisingly little meal. It was surmised that the exposure to frequent shifts onto fresh pasture stimulated intake of pasture, and removed the advantage of feeding calves higher levels of milk and supplementation with meal. Anecdotally, many calves when removed from rearing sheds to pasture are kept on the same paddocks as they are not a high priority for pasture allocation. Therefore, the aim of this experiment was further collection of colostral and Brix data as described by Coleman et al. (2015), and to compare pre-weaning growth rates of calves that are continually offered fresh pasture to those that are set stocked.}, issn = {1176-5283}, author = {Back PJ and Hickson RE and van Bouwel K and de Cock H and Verdurmen J and Sneddon NW and Laven RA} } @conference {3672, title = {Grazing behaviour and species selection of heifer calves fed different forages.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {126-131}, address = {Adelaide}, abstract = {

The aim of this experiment was to determine whether there was a difference in the behaviour of calves grazing different forages. Weaned dairy heifer calves (n = 64) were assigned to two different forage feeding treatments: ryegrass pasture and a clover-herb mix. Behavioural observations were recorded every 10 minutes over a 72 h period. Behaviours recorded were standing, walking, lying or sitting, grazing, ruminating, drinking/grooming, playing and various combinations of these. Calves grazing pasture spent more time lying and ruminating compared to calves grazing the clover-herb mix (34.6\% vs 16.7\%), and less time standing and grazing (17.2\% vs 32.2\%). Calves were less active from late evening and early morning and more likely to be ruminating earlier in the day and grazing later in the day. Plant selection (measured as plant disappearance rate) was determined in calves grazing the clover-herb mix. Red clover had the highest disappearance rate on all days compared to other species (P\<0.05). Plantain, chicory and white clover eaten on day one did not differ in proportions eaten, but by day three less red clover and chicory remained compared to plantain and white clover (P\<0.05).

}, issn = {1176-5283}, author = {Back PJ and Hickson RE and Lilly VM and Coleman LW and Sneddon NW and Laven RA} } @conference {3672, title = {Supply curves for yields of dairy products from first-lactation Holstein Friesian, Jersey and Holstein Friesian-Jersey crossbred cows accounting for seasonality of milk composition and production.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {139-143}, address = {Adelaide}, abstract = {The economic efficiency of a milk-processing system is influenced by seasonality of the milk supply, and changes to milk composition, influences the product potential of that milk. Lactation curves for milk yield and composition for seasonal calving first-lactation Holstein Friesian (F), Jersey (J) and Holstein Friesian-Jersey crossbred (FxJ) cows were used as inputs in a deterministic simulation model to produce seasonal curves for daily yields of dairy products. The dairy products were whole milk powder, skim milk powder, cheese, or butter. Dairy product potential was estimated for each animal from a population of 4333 mixed-breed, first-lactation cows. Lactation lengths differed (P<0.0001), among F, FxJ, and J, which averaged 219, 222 and 221 days respectively. Total-lactation milk yield was different (P<0.0001) among breeds and averaged 3257, 3092 and 2902 litres for F, FxJ and J cows, respectively. Whole-milk powder potential (yield per 1000 L of milk) was greatest at the start of the season and least at the end of the season, whereas cheese-production potential (yield per 1000 L of milk) followed the opposite pattern. Total-lactation whole-milk powder yield was different among breeds (P<0.0001) at 366, 338 and 312 kg of whole-milk powder for F, FxJ and J cows, respectively. Total-lactation cheese yield was also different among breeds (P<0.0001), and was 371, 375 and 361 kg for F, FxJ and J cows, respectively. The supply curves indicate that milk is best processed into whole or skim milk powder during peak season, and cheese and butter at the end of lactation. However, seasonal production of specific products would limit the use of by-product lactose from cheese manufacture in the production of milk powders, and thus negate the efficiency gains from changes to processing priorities.}, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Davis SR and Hickson RE and Shalloo L and Garrick DJ} } @conference {3672, title = {Estimation of crossbreeding effects on yields of dairy products and value of milk processed in different product portfo}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {48-53}, address = {Dunedin}, abstract = { The international market requires milk products to meet specified minimum standards that define acceptable composition. This study used a deterministic simulation model to estimate milk products yields of individual cows for different export markets. Four milk product portfolios were analysed which included 100\% of the milk to either whole-milk powder (WMP), skim-milk powder, cheese, or butter. Milk product potential was estimated for 4310 mixed-breed heifers from LIC Sire Proving Scheme herds based on total lactation production. Lactation lengths were 212, 214 and 213 days for Holstein Friesian (HF), Holstein Friesian-Jersey crossbreds (HFxJ), and Jerseys (J) respectively. Milk yields were significantly different between breeds averaging 3121 for HF, 2947 for HFxJ, and 2751 litres for J cows. Holstein Friesians had the lowest fat, protein and lactose concentrations, whereas J had the highest. Holstein Friesian had the greatest yields of WMP per 1000 litres of milk, whereas J had the least. For all scenarios, J milk was most valuable per litre. Crossbred cows provided greater total milk income for all scenarios except 100\% butter. Positive heterosis effects were estimated for first-cross HFxJ animals for milk production and product yields. Crossbreeding produces cows with milk better suited to the processing requirements of the New Zealand dairy industry and returning greater value to the New Zealand dairy farmer.}, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Hickson RE and Shalloo L and Garrick DJ} } @conference {3678, title = {Supply and demand for lactose in the New Zealand dairy industry}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {215-219}, address = {Napier}, abstract = {Global milk product demand has been rapidly growing in the past decade, which is reflected in an increased demand for milk powders. The New Zealand dairy industry is capitalising on this by shifting its product portfolio towards milk powders. However, current international product specifications in combination with New Zealand milk composition and an industry objective to maximise farm profitability makes the industry deficient in milk lactose. This study aimed to determine how lactose deficit or surplus is influenced by changes in the product portfolio. In order to quantify this lactose balance, a computer simulation model was used (Moorepark Processing Sector Model). The 2012 New Zealand milk production (19.129 billion litres, milkfat concentration (4.99\%), protein concentration (3.82\%) and lactose concentration (4.70\%, anhydrate)) was used within the analysis. Four manufacturing portfolio scenarios were investigated with different proportions of milk diverted to whole milk powder production (80\%, 60\% (current proportion), 30\% and 10\%). The model simulated the total production of whole milk powder, skim milk powder, casein, whey powder, buttermilk powder, butter and cheese. Whole milk powder production varied from 2,292,000 tonnes for the 80\% scenario to 286,000 tonnes for the 10\% scenario. Lactose mass balance varied from 214,000 tonnes in deficit for the 80\% scenario to 510,000 tonnes in surplus for the 10\% scenario. These analyses indicate that as more whole milk powder is produced, milk from current New Zealand cows results in an increased deficit of milk lactose. The national breeding objective could be adjusted to reflect changes in the future product portfolios to better align the composition of milk with the likely product mix.}, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Hickson RE and Shalloo L and Garrick DJ and Geary U} } @conference {89263, title = {Review of milk payment systems to identify the component value of lactose}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {33-36}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

New Zealand{\textquoteright}s export dairy product mix has shifted towards the production of whole milk powder. This has resulted in a deficit in milk lactose to meet international standardisation requirements for whole milk powder. Currently, the deficit in lactose is filled using imported lactose with an estimated cost of New Zealand dollars 300 million annually. This study compares payment systems from America, Europe, Australia and New Zealand, and outlines possible strategies for payment for lactose to New Zealand dairy farmers. The prominent milk payment system in New Zealand is the {\textquoteleft}A+B-C{\textquoteright} multiple component pricing system, where A and B are the monetary values per kilogram of fat and protein and C is the penalty per litre of milk volume. An alternative payment system that may encourage farmers to increase the supply of lactose could be {\textquoteleft}F+P+L-V{\textquoteright} where F, P and L are the monetary values of fat, protein and lactose respectively and V is the penalty per litre of milk volume. This payment system is currently in operation at one small New Zealand dairy processor. This study has shown that the {\textquoteleft}F+P+L-V{\textquoteright} payment system results in smaller deviation from the true value of the milk for differing breeds, milk compositions and product mixes than the current {\textquoteleft}A+B-C{\textquoteright} system of milk payment.

}, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Hickson RE and Shalloo L} } @conference {78991, title = {Genetic parameters for lactose and its relationship with concentrations and ratios of other milk components}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {76-80}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {

The objective of this study was to estimate genetic parameters for milk yields, milk concentrations and ratios of milk components. Herd-test records from 268 Jersey cows from a Waikato dairy farm were obtained along with pedigree information. Genetic and phenotypic (co)variances for daily yields of milk (MY), fat (FY), protein (PY), milksolids (MSY; FY + PY) and lactose (LY), percentages of fat, protein, and lactose, and ratios of protein to fat (P:F) and protein to protein plus lactose (P:PL), and somatic cell score, were obtained with single trait and bivariate animal models using a restricted maximum likelihood methodology. The models included the fixed effects of month of calving and days in milk, modelled using an exponential curve, lactation number and the random effects of animal and cow permanent environment effects were also included in the model. Heritability estimates were 0.50 {\textpm} 0.12 (standard error) for MY, 0.25 {\textpm} 0.10 for FY, 0.30 {\textpm} 0.12 for PY, 0.27 {\textpm} 0.11 for MSY, 0.50 {\textpm} 0.12 for LY, 0.24 {\textpm} 0.04 for P:F ratio and 0.53 {\textpm} 0.04 for P:PL ratio. The genetic correlations for daily yields were high and positive. The genetic correlation between MSY and P:F ratio was -0.35 indicating that increases in MSY under the current breeding objective will decrease the P:F ratio, thus departing from an optimal ratio for whole milk powder processing.

}, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Hickson RE and Shalloo L} } @conference {75908, title = {Efficiency, cheese yield and carbon emissions of Holstein-Friesian, Jersey and crossbred cows: an overview}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {214-218}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {This paper provides an overview on differences between Holstein-Friesian (HF), Jersey (J) and crossbred cows, for feed conversion efficiency (FCE), dry matter intake (DMI), cheese yield and carbon emissions. It was found that J cows have significantly higher DMI per kilogram of live weight (LWT) compared to HF and F1 HFxJ cows (3.64, 3.81 and 3.23 g DMI/kg LWT, respectively). A higher DMI per kilogram of LWT can result in more energy available for milk production, assuming that the maintenance requirements per unit of LWT are equal between the breeds. Estimates of FCE measured as grams of milksolids (milkfat plus milk protein) per kilogram of DMI were higher in J than HF cows (112 vs 97 g MS/kg DMI) in the reviewed papers. For grazing cows, a higher proportion of feed consumed is converted into milk production than used to cover maintenance energy requirements in J cows. This may result in lower greenhouse gas emission intensity from J than HF cows. Opportunities for the utilisation of breed differences to increase FCE and reduce carbon footprint and increase overall farm profitability in grazing dairy systems requires further farming system research to elucidate the relative efficiencies of the most common dairy breeds.}, issn = {1176-5283}, author = {Sneddon NW and Lopez-Villalobos N and Baudracco J} }