Effects of a novel pressed dried distillers grain block during late gestation on dry matter intake and cow performance and the impacts of feed efficiency on reproductive performance.

摘要

Feed costs account for approximately 70% of total production costs in beef cattle operations. Therefore, considering ways to reduce feed intake is necessary to remain profitable. Cattle grazing high elevation range lands of the northwestern United States typically require protein and/or energy supplementation during the winter months when nutrient requirements are increased. Selection of a supplementation program that is effective and minimizes additional costs is imperative. The first study was conducted to 1) evaluate effects of supplementation with a self-limiting pressed dried distiller's grain block, SweetProRTM 16, on cow BW, body composition, and hay intake in late gestation, 2) monitor birth weights and growth characteristics of subsequent offspring. It was determined that supplementation with the SweetProRTM 16 decreased intake of forage and increased cow BW and BCS. However, supplementation did not affect body composition, circulating progesterone concentrations, birth weight or pre-weaning growth of offspring. While nutrition represents the largest cost to cow-calf producers, a successful reproductive program is the primary factor affecting profitability. Selection for highly feed efficient cattle may be related to decreased fat deposition leading to increased age at puberty. The second study was conducted to determine if selection for feed efficient heifers may result in decreased reproductive efficiency. Specifically, our objectives were to evaluate the effects of residual feed intake (RFI) ranking on BCS, growth, age of puberty, conception rate, pregnancy rate, and ovarian antral follicle count (AFC). An additional objective was to compare the results of actual RFI for these heifers versus their predicted residual feed intake (PRFI) estimated by the Cornell Cattle Value Discovery System (CCVDS). It was determined that when RFI was predicted using CCVDS, weaning weights, ADG, pre-breeding BW and BCS were greater for heifers with high PRFI compared to heifers with low PRFI. In addition, AFC did not differ between PRFI rankings but high PRFI heifers tended to have greater first service conception rates and did have greater overall pregnancy rates compared to low PRFI heifers. Alternatively, actual RFI rank did not affect BW, body composition, AFC, or fertility but low RFI heifers consumed 21% less feed inputs compared to high RFI heifers. The Cornell system was not a valuable tool for predicting individual heifer RFI ranking, which suggests that performance tests are still necessary for reliable RFI rankings of growing beef heifers.