Short communication: Genetic differences between New Zealand and North American dairy cows alter milk production and gluconeogenic enzyme expression

• Published in: Journal of dairy science Vol. 95; no. 1; pp. 455 - 459
• Main Authors: White, H.M, Donkin, S.S, Lucy, M.C, Grala, T.M, Roche, J.R
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 2012; Elsevier
• Subjects: Animal productions; Animals; biochemical pathways; Biological and medical sciences; biopsy; blood glucose; Breeding; calving; Cattle - genetics; dairy cows; diet; Feeding. Feeding behavior; Female; free fatty acids; Fundamental and applied biological sciences. Psychology; Gene Expression - genetics; genotype; Gluconeogenesis - genetics; insulin; lactation; Lactation - genetics; liver; Liver - enzymology; messenger RNA; milk; milk production; New Zealand; North America; Phosphoenolpyruvate Carboxylase - genetics; Phosphoenolpyruvate Carboxylase - metabolism; pyruvate carboxylase; Pyruvate Carboxylase - genetics; Pyruvate Carboxylase - metabolism; Real-Time Polymerase Chain Reaction - veterinary; Terrestrial animal productions; Vertebrates; Vertebrates: anatomy and physiology, studies on body, several organs or systems; New Zealand; Oceania; North America; Carbon-carbon ligases; Genetic selection; Farming animal; Enzyme; Dairy cattle; Milk production; Pyruvate carboxylase; Feeding; concentrate supplementation; Vertebrata; Mammalia; Ligases; Dairy industry; Genetics; Cow milk; North; Artiodactyla; Concentrate; Supplementation; Ungulata
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2011-4598

Continuous selection of dairy cows for production traits may alter the regulation of metabolic pathways. High-producing North American (NA) cows produce more milk and have a larger degree of somatotropic axis uncoupling than less intensively selected New Zealand (NZ) cows. The objective of this study was to determine if production-based selection priorities (i.e., NA cows) have altered the regulation of the gluconeogenic pathway relative to selection priorities based on production traits (i.e., NZ cows). In this study conducted in New Zealand, NZ (n=27) and NA cows (n=27) were monitored from 1 wk before calving to 12 wk post-calving. Cows were pasture-fed and supplemented with 0, 3, or 6kg of concentrate DM/d. Liver biopsy samples were collected at 0, +1, and +4 wk relative to calving (WRTC) for mRNA analysis. Milk production of NA cows was greater during wk 5 to 11 postpartum and concentrate supplementation increased milk production for both NA and NZ cows. No genotype (NA vs. NZ) by diet interaction occurred for blood glucose, NEFA, or insulin. Expression of pyruvate carboxylase (PC) mRNA was increased at +1 and +4 WRTC compared with 0 WRTC (3.04 and 2.42 vs. 1.25±0.13 arbitrary units, respectively: mean ± standard error of the means) and expression of cytosolic phosphoenolpyruvate carboxykinase mRNA was increased at +4 compared with calving and +1 WRTC (4.78 vs. 2.18 and 2.48±1.41 arbitrary units, respectively). Expression of PC mRNA tended to be greater in NZ cows and tended to decrease with concentrate supplementation in both NZ and NA cows. The responses of NZ and NA cows to the transition to lactation and concentrate supplementation appeared to be similar; however, NZ cattle had a higher basal expression of PC.