Effects of level and source of fat in the diet of gestating beef cows on the pre-partum performance of the dam and birth weight of the progeny
F Añez-Osuna, G Penner, C Fitzsimmons, M Dugan, J Campbell, P Jefferson, H Lardner, J McKinnon, 351 Effects of level and source of fat in the diet of gestating beef cows on progeny performance., Journal of Animal Science, Volume 96, Issue suppl_3, December 2018, Page 175, https://doi.org/10.1093/jas/sky404.381
Plain language summary
A two-year study was conducted to evaluate the effects of level and source of fat in the diet of gestating beef cows on their pre-partum performance and the birth weight of their progeny. Each year pregnant cows were fed one of three diets: low fat (LF) (grass-legume hay, barley straw, and barley grain), high fat canola (CAN) (base diet plus canola), or high fat flaxseed (FLX) (base diet plus flax). After 160 d on trial, body weight and condition score of LF cows were greater than both HF diets. Also, feeding FLX diet over gestation resulted in greater concentration of certain unsaturated fatty acids greater in subcutaneous adipose tissue (SCAT) when compared to CAN diet. Cows receiving the LF diet over gestation gave birth to lighter calves compared to those receiving the HF diets, with no difference between calves born to CAN and FLX cows. In conclusion, these data suggest a partitioning of the metabolizable energy in pregnant beef cows which that is dependant on the type of dietary energy, resulting in heavier calves at birth for cows fed high-fat diets.
A two-year study was conducted to evaluate the effects of level and source of fat in the diet of gestating beef cows on progeny performance. Each year, 75 multiparous pregnant Angus cows (182 ± 4.8 d pre-calving) were randomly assigned to 15 pens, which were randomly assigned to one of three dietary treatments: a low-fat diet (LF; 1.4 ± 0.03% EE) comprised of 72% forage and 28% barley grain, and two high-fat diets (HF; 3.3 ± 0.03% EE) where a canola seed (CAN) or a flaxseed (FLX) based pellet were included to provide 300 g/cow/d of fat as MUFA or PUFA sources, respectively. Diets were formulated to be iso-caloric, iso-nitrogenous, and to meet nutrient requirements for the last two trimesters of gestation. All cows and calves were fed and managed similarly after calving. Data were analyzed as a randomized complete block design with contrasts to separate the effects of level (LF vs. HF) and source (CAN vs. FLX) of fat. Calving dates were not different (P=0.80) among treatments. Calves from HF cows were heavier (P≤0.04) at birth (43.0 ± 0.5 vs. 40.0 ± 0.3 kg) and slaughter (627 ± 7.1 vs. 601 ± 11.4 kg) than those from LF cows. When data were analyzed according to sex, bull-calves from HF cows were heavier (P<0.01) at birth than those from LF (44.9 ± 0.7 vs. 41.5 ± 0.5 kg) with no difference (P=0.70) between bull-calves from CAN (44.7 ± 0.7 kg) and FLX (45.1 ± 1.2 kg) cows. At slaughter, steers from HF cows showed greater cumulative-ADG (1.32 ± 0.02 vs. 1.26 ± 0.02 kg/d), shrunk-BW (629 ± 7.5 vs. 598 ± 9.5 kg), and HCW (371 ± 4.3 vs. 352 ± 5.2 kg) than those from LF, with no difference (P≥0.11) between steers from CAN and FLX cows. No differences (P≥0.10) were found on heifer performance. These results indicate that male progeny performance can be enhanced by manipulating the level of fat in the diet of gestating beef cows, possibly due to developmental programming.