Effects of reduced in utero and post-weaning nutrition on milk yield and composition in primiparous beef cows

• Published in: Animal (Cambridge, England) Vol. 11; no. 1; pp. 84 - 90
• Main Authors: Waterman, R. C., Geary, T. W., Petersen, M. K., MacNeil, M. D.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.01.2017; Elsevier
• Subjects: analysis of variance; Animal Feed - analysis; Animal Nutritional Physiological Phenomena; Animals; beef cows; calves; Cattle - physiology; Diet - veterinary; Dietary Supplements; feed supplements; Female; forage; heifer development; heifers; lactation; Lactation - physiology; lactation curve; lactose; livestock production; Male; maternal nutrition; Maternal Nutritional Physiological Phenomena; milk; Milk - chemistry; milk and constituent yield; milk composition; milk yield; milking machines; nutrient content; Parity; parturition; Physiology and functional biology of systems; Postpartum Period; Pregnancy; Prenatal Nutritional Physiological Phenomena; primiparous beef cow; rearing; Research Article; Seasons; semiarid zones; steers; uterus; Weaning; weanlings; winter; heifer development; primiparous beef cow; milk and constituent yield
• ISSN: 1751-7311; 1751-732X; 1751-732X
• DOI: 10.1017/S1751731116001257

Development and long-term retention of replacement beef females in a semi-arid environment are of a major concern for extensive livestock producers. Furthermore, the demand of not only producing a thriving, healthy calf, but having sufficient milk to support that first calf is essential. To address this issue, we conducted a 3-year study measuring milk production and milk constituent yields in primiparous beef heifers (n=48; 16/year reared under two different feeding regimens) raising steer calves. Cows received 1.8 or 1.2 kg/day winter supplementation for ~80 day before parturition and their heifer calves were then randomly assigned to heifer development treatments that provided ad libitum (AL) or 80% (less than ad libitum (LAL)) of ad libitum feed post weaning. Heifers developed on the AL treatment also received 1.8 kg/day winter supplementation for life, whereas heifers developed on the LAL treatment received 1.2 kg/day winter supplementation for life. Milk production of primiparous cows was measured with a portable milking machine every other week from days 27 to 125 postpartum. Milk yield for the 125-day lactation period was calculated from area under the lactation curve approximated by trapezoidal summation. The ANOVA model included in utero winter nutrition, post-weaning heifer development treatment, year and their interaction. Heifers subjected to the AL treatment reached peak milk yield ~12.3 day later (P=0.02) than heifers receiving LAL treatment. In addition, an in utero nutrition×post-weaning heifer treatment×year interaction existed (P⩽0.04) for milk peak yield, average daily milk yield (kg/day) and nutrient composition (protein, lactose, fat, solids non-fat, g/day). These interactions manifest as changes in magnitude and rank across the 3 years of the study. Livestock production in extensive environments is subject to variations in seasonal precipitation patterns and quality and quantity of grazeable forage and these fluctuations have a large impact on milk yield. In summary, the gestational nutritional environment of a heifer’s mother may interact with the heifer’s nutrient consumption during post-weaning growth and the current year to trigger variation in year-to-year milk production.