Añez-Osuna Federico, Penner Gregory B, Campbell John, Dugan Michael E R, Fitzsimmons Carolyn J, Jefferson Paul G, Lardner Herbert A, McKinnon John J
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada.
Western Beef Development Centre, Humboldt, SK, Canada.
J Anim Sci. 2019 May 16;97(7):3120-41. doi: 10.1093/jas/skz172.
A study was conducted to evaluate the effects of level and source of fat in the diet of gestating beef cows on the postpartum performance of the dam and the progeny. Each year, 75 mature pregnant (183±4.8 d until calving) Angus cows with similar BW (663±21.5 kg) and BCS (2.6±0.12; 1 to 5 scale) were randomly assigned to one of 15 outdoor pens. Each pen was assigned to one of three iso-caloric and iso-nitrogenous treatments: a low-fat diet (LF; 1.4±0.12% EE), and two high-fat diets (HF; 3.3±0.20% EE) including a canola seed (CAN) or a flaxseed (FLX) based pelleted feed. Diets were formulated to meet the requirements of pregnant beef cows and fed until calving. Data were analyzed as a randomized complete block design with contrasts for the effects of level (LF vs. HF) and source (CAN vs. FLX) of fat. No differences (P≥0.21) were found for BW or calving to weaning ADG of cows. The average BCS during the first 42 d of lactation was greater (P<0.01) for LF compared to HF (2.63 vs. 2.51) with no difference (P=0.35) for CAN vs. FLX cows. Subcutaneous fat thickness over the ribs was greater (P≤0.01) for LF compared to that of HF cows at calving (5.7 vs. 4.3 mm) and at weaning (4.3 vs. 3.7 mm) with no difference (P≥0.11) for CAN vs. FLX cows. Over the first 42 d of lactation, no difference (P≥0.23) was observed for 12-h milk yield. Milk protein concentration was greater (P=0.03) for CAN compared to FLX (3.11 vs. 3.01%) cows while no difference (P≥0.28) was observed for any other milk component. Milk fat from FLX cows had greater (P < 0.01) CLA and CLnA concentrations than that of CAN cows during the first 42 d of lactation. Pregnancy rate of HF cows tended (P=0.07) to be greater than that of LF cows with no difference (P=0.77) for CAN vs. FLX cows. Calves from HF cows were heavier (P≤0.01) at birth (42.9 vs. 40.2 kg) than those from LF cows. From calving to weaning, ADG of calves born to CAN cows was greater (P=0.03) that that of calves born to FLX cows (1.19 vs. 1.13 kg/d) with no difference (P=0.18) for calves born to LF vs. HF cows. At slaughter, progeny of HF cows had greater (P≤0.03) shrunk BW (605 vs. 579 kg) and HCW (355 vs. 339 kg) compared to those from LF cows with no difference (P≥0.16) for progeny of CAN vs. FLX cows. These results show that feeding a HF diet over gestation results in heavier calves at birth and at slaughter, and superior calf gains from birth to slaughter as well as heavier carcasses, possibly due to a developmental programming effect.
开展了一项研究，以评估妊娠肉牛日粮中脂肪水平和来源对母牛产后性能及后代的影响。每年，将75头体重（BW）相近（663±21.5千克）且体况评分（BCS，1至5分制，2.6±0.12）的成熟怀孕安格斯母牛（产犊前183±4.8天）随机分配到15个室外围栏中的一个。每个围栏被分配到三种等热量、等氮处理之一：低脂日粮（LF；1.4±0.12% 乙醚浸出物），以及两种高脂日粮（HF；3.3±0.20% 乙醚浸出物），其中一种基于油菜籽（CAN）颗粒饲料，另一种基于亚麻籽（FLX）颗粒饲料。日粮配方满足怀孕肉牛的需求，并一直喂至产犊。数据采用随机完全区组设计进行分析，并对脂肪水平（LF与HF）和来源（CAN与FLX）的影响进行对比。母牛的体重或产犊至断奶的平均日增重（ADG）未发现差异（P≥0.21）。泌乳前42天，LF组母牛的平均BCS高于HF组（P<0.01）（2.63对2.51），CAN组与FLX组母牛无差异（P=0.35）。产犊时（5.7对4.3毫米）和断奶时（4.3对3.7毫米），LF组母牛肋骨处的皮下脂肪厚度大于HF组（P≤0.01），CAN组与FLX组母牛无差异（P≥0.11）。泌乳前42天，12小时产奶量未观察到差异（P≥0.23）。CAN组母牛的乳蛋白浓度高于FLX组（P=0.03）（3.11对3.01%），其他乳成分未观察到差异（P≥0.28）。泌乳前42天，FLX组母牛的乳脂中CLA和CLnA浓度高于CAN组（P < 0.01）。HF组母牛的怀孕率有高于LF组的趋势（P=0.07），CAN组与FLX组母牛无差异（P=0.77）。HF组母牛所产犊牛出生时体重（42.9对40.2千克）高于LF组（P≤0.01）。从产犊到断奶，CAN组母牛所产犊牛的ADG高于FLX组（P=0.03）（1.19对1.13千克/天），LF组与HF组母牛所产犊牛无差异（P=0.18）。屠宰时，HF组母牛的后代收缩体重（605对579千克）和热胴体重（355对339千克）高于LF组（P≤0.03），CAN组与FLX组母牛的后代无差异（P≥0.16）。这些结果表明，妊娠期饲喂高脂日粮会导致犊牛出生时和屠宰时体重更重，从出生到屠宰犊牛增重更快，胴体更重，这可能是由于发育程序化效应。
