张家川红花牛断奶母犊分阶段饲养效果试验OA

To evaluate the effects of phased rearing on the growth,development and breeding economic be-nefits of weaned heifer calves and cultivate high-quality replacement heifers,60 healthy weaned Zhangjia-chuan Honghua cattle heifer calves with body weight close to 150 kg were selected and randomly divided into a test group and a control group,with 30 calves in each group.The control group adopted the traditio-nal rearing method.For the experimental group,based on the Feeding Standard of Beef Cattle(NY/T 815-2004),phased dietary formulas with a target average daily gain(ADG)of 1.0 kg were designed by linear programming using local feed ingredients,corresponding to body weights of 150,175,200 and 225 kg,respectively.The dietary formulas were optimized by artificial intelligence(AI)and processed with total mixed ration(TMR)technology before feeding.The experiment consisted of a 7-day pre-experimental pe-riod and a 100-day formal experimental period.The changes in body weight,body size and body conforma-tion,feed intake,feed conversion efficiency and input-output ratio of the calves were measured and ana-lyzed.The results showed that the calves in the experimental group grew and developed well,and the growth of body weight and body size at each stage fell within a reasonable range,meeting the optimal body condition standard for growing heifers before reproduction.The ADG of heifer calves in the experimental group was(1 022.4±19.76)g,and the daily increments of body height,body oblique length and chest cir-cumference were 0.172 cm,0.184 cm and 0.246 cm,respectively,which were 127.55％,132.43％,113.95％and 123.64％higher than those in the control group.In the experimental group,93.33％of the heifer calves maintained a moderate body condition with a body condition score(BCS)of 2.5 points fat and lean,while the proportion of obese female calves in the control group with a body condition of 4.0 points was as high as 83.33％.The average daily gain income per head was 19.66 yuan in the experimental group and 4.11 yuan in the control group;the input-output ratio was 1.79 in the experimental group and 0.44 in the control group,both significantly higher than the control group(P≤0.01).In summary,the series of phased rearing dietary formulas can accurately meet the nutritional requirement for 1 kg ADG,with good feeding effects,and can also improve the subsequent reproductive performance of heifer calves,and significantly enhance breeding economic benefits.