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

Authors: Waterman, Richard; Geary, Thomas; Petersen, Mark; MACNEIL, M - Retired ARS Employee

Submitted to: Animal-The International Journal of Animal Biosciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2016
Publication Date: 6/30/2016
Publication URL: http://handle.nal.usda.gov/10113/5801792
Citation: Waterman, R.C., Geary, T.W., Petersen, M.K., MacNeil, M.M. 2016. Effects of reduced in utero and post-weaning nutrition on milk yield and composition in primiparous beef cows. Animal-The International Journal of Animal Biosciences. 11(1): 84-90. doi:10.1017/S1751731116001257.

Interpretive Summary: Raising livestock in extensive rangeland environments relies heavily on the nutritional quality of grazeable forage. Livestock producers often encounter times of the year when grazeable forage is inadequate to meet animal requirements and therefore, must supply harvested feed resources which are a major economic cost. This indicates a need to identify new and acceptable approaches to sustain optimal levels of production while ensuring economic success of the operation. The critical role nutrition portrays in achieving maximal reproduction is well documented. Previous research has demonstrated that when reared with reduced harvested feed input during pre-pubertal development and subsequent winters, body weight, body condition score and reproductive success of heifers may depend on the amount of feed received by their dams, thus indicating a potential uterine programming Previous research also indicates cows varying in milk yield and with similar genetic potential for mature weight may have different production efficiencies. This study concludes that dams managed on two levels of winter harvested feed inputs during late pregnancy may have lifetime treatment influences on their female offspring. Furthermore, a reduction in harvested feed input during post weaning heifer development had no detrimental impact on milk yield, milk constituents, and calf BW, but decreased feed input during this period resulted in earlier peak milk production. The long term goal for this study herd is to evaluate lower nutrient input levels on lifetime productivity. Results derived from the present study suggest reduced supplemental feed may provide an opportunity to save on cost associated with feeding harvested feedstuffs and still maintain a optimal level of performance.

Technical Abstract: Can range livestock producers reduce harvested feed inputs, during late pregnancy and heifer development, and maintain sustainable and acceptable production goals? To address this, we conducted a 3-yr study measuring milk production and milk constituent concentrations in primiparous beef heifers (n = 48; 16/yr reared under two different feeding regimes) raising steer calves. Grandams from a composite herd received 1.8 or 1.2 kg/d winter supplementation for approximately 80 d and their heifer calves were then randomly assigned to heifer development treatments that provided ad-libitum or 20% less feed post weaning. Heifers developed on the ad-libitum treatment also received 1.8 kg/d winter supplementation for life, whereas heifers developed on the 20% less treatment received 1.2 kg/d winter supplementation for life. Milk production was measured with a portable milking machine every other week from d 28 to126 postpartum. Milk yield for the 126-d lactation period was calculated from area under the lactation curve approximated by trapezoidal summation. The analysis of variance model included dam winter nutrition, heifer development treatment, year and their interaction. A heifer development treatment × year interaction existed for on-test body weight (P = 0.01); however, this interaction was absent at subsequent measures of body weight at onset of breeding and at time of pregnancy diagnosis (P = 0.88). Body weight of steer calves did not differ for adjusted 205 d weaning weights (P = 0.14). Heifers receiving ad-libitum feed reached peak milk concentration approximately 9 d later (P = 0.04) than heifers receiving the 20% less development treatment. All other milk production measures and constituents except for days to reach peak milk concentration did were not influenced by dam or heifer development treatment (P = 0.10). However, a grandam × heifer treatment × year interaction existed for milk peak concentration (P = 0.01) and a grandam treatment × year interaction existed for milk protein (P = 0.03) and butterfat concentrations (P = 0.01). These interactions occurred with changes in direction and ranking across the 3 years of the study. In summary a heifer’s dam (grandam; in utero) may have some influence on subsequent offspring of her daughters. However, heifers receiving less developmental feed weaned steer calves of similar weight to those produced by their more liberally fed contemporaries.