Format

Send to

Choose Destination
J Anim Sci. 2019 May 16. pii: skz171. doi: 10.1093/jas/skz171. [Epub ahead of print]

Level and source of fat in the diet of gestating beef cows: I. Effects on the pre-partum performance of the dam and birth weight of the progeny.

Author information

1
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada.
2
Western Beef Development Centre, Humboldt, SK, Canada.
3
Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, SK, Canada.
4
Agriculture and Agri-Food Canada, Lacombe Research and Development Centre, Lacombe, AB, Canada.
5
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.

Abstract

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 birth weight of progeny. Each year, 75 multiparous (≥3 calving) pregnant Angus cows were stratified by BW (663±21.5 kg) and BCS (2.6±0.12; 1 to 5 scale), and randomly assigned to one of fifteen outdoor pens. Subsequently, each pen was randomly assigned to one of three (n=5) treatments: a low-fat diet (LF; 1.4±0.12% EE) consisting of grass-legume hay, barley straw, and barley grain; or one of two high-fat diets (HF; 3.3±0.20% EE) that included either a canola seed (CAN) or a flaxseed (FLX) based pelleted feed. Diets were formulated to meet the requirements of pregnant beef cows during the last two trimesters of gestation (183±4.8 d), adjusted for changes in environmental conditions, and offered such that each pen on average received similar daily amounts of digestible energy (DE; 31.2±2.8 Mcal/cow), CP (1.36±0.13 kg/cow), and DM (12.9±1.0 kg/cow). 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. After 160 d on trial, conceptus corrected-BW (CC-BW) of LF cows (708 kg) and the proportion of over-conditioned cows (13.2%) were greater (P≤0.04) than those of HF, with no difference (P≥0.84) between CAN and FLX for CC-BW (697 kg) and proportion of over-conditioned cows (3.6 vs. 2.9%). Feeding FLX diet during gestation resulted in cows with a greater (P≤0.01) concentration of CLnA (0.12 vs. 0.05%) and n-3 (0.58 vs. 0.37%) fatty acids, and a tendency (P=0.09) for CLA concentration (1.05 vs. 0.88%) to be greater in subcutaneous adipose tissue (SCAT) when compared to cows fed the CAN diet. By the end of gestation, serum NEFA concentration of LF cows (592 µEq/L) was lower (P<0.01) than that of HF cows, and FLX cows had greater (P<0.01) serum NEFA concentration than CAN cows (636 vs. 961 µEq/L). Cows receiving the LF diet during gestation gave birth to lighter (P<0.01) calves compared to those receiving the HF diets (40.2 vs. 42.9 kg), with no difference (P=0.24) between calves born to CAN (42.4 kg) and FLX (43.3 kg) cows. In conclusion, these results suggest a partitioning of the ME in pregnant beef cows that is dependent on the type of dietary energy, resulting in heavier calves at birth for cows fed high-fat diets. Also, the type of fatty acid in the diet of gestating beef cows affected the fatty acid profile in SCAT and serum NEFA concentration.

PMID:
31095685
DOI:
10.1093/jas/skz171

Supplemental Content

Full text links

Icon for Silverchair Information Systems
Loading ...
Support Center