Blood metabolic profiles were determined from 40 days prepartum to 60 days postpartum in Uruguayan Holstein (UH) (n = 13) and UH x New Zealand Holstein-Friesian first cross (UH-NZHF) (n = 13) cows with seven in each group experiencing their second lactation (L2) and six experiencing their third lactation (L3). Non-esterified fatty acids increased around calving and tended to be greater in UH-L3 cows as well as betahydroxybutyrate concentrations for 20 days after calving, consistent with the greater body condition score losses in this group. The UH cows had greater prepartum total protein concentrations than UH-NZHF cows. Concentrations decreased around calving and increased immediately thereafter. In UH-NZHF-L2 cows, total protein levels were consistently low throughout lactation. UH-NZHF L3 cows had greater albumin concentrations than UH L3 cows. Insulin concentrations were not affected by strain or lactation number and were diminished around calving. A similar pattern was found for IGF-1, although an interaction between strain and days-in-milk was found. Compared to UH cows, UH-NZHF cows had greater levels of IGF-1 at 35 days prepartum but lower levels of IGF-1 at calving. These data suggest that UH cows, especially L3 cows, had a more pronounced negative energy balance than UH-NZHF cows that may reflect a different pattern of nutrient partitioning possibly related to different pregnancy rates.
Proceedings of the New Zealand Society of Animal Production, Volume 70, Palmerston North, 311-315, 2010
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