PSV-2 Effect of feeding level during feedlot backgrounding on animal growth and feed efficiency of the winter-spring period

IF 2.7 2区农林科学 Q1 AGRICULTURE, DAIRY & ANIMAL SCIENCE

Journal of animal science Pub Date : 2025-05-20 DOI:10.1093/jas/skaf102.377

Natalia Zabalveytia, Alvaro Simeone, Oscar Bentancur, María V Burjel, Stefania Pancini, Virginia Beretta

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Abstract

This study evaluated the effect of winter backgrounding feeding system (grazing vs. feedlot) and the amount of feed offered in the feedlot (FO) on average daily gain (ADG) and feed-to-gain ratio (FG) during the overall winter-spring period (182 days). Forty Hereford female calves (159 ± 25 kg body weight (BW)) were randomly assigned to one of five treatments during winter (98 days): grazing winter grass pasture at a forage allowance of 5 kg dry matter (DM) per 100 kg BW, or receiving a feedlot total mixed ration (70% concentrate/ 30% roughage) differing in FO (2.2%, 2.5%, 2.9%, and 3.2% BW on a DM basis). During spring (84 days), all treatments grazed a mixed grass-legume pasture (6 kg DM/100 kg BW, 2524 ± 880 kg DM/ha) in weekly plots (n = 2 plots/ treatment). BW was recorded every 14 days. DMI was measured daily at feedlot and estimated on even weeks as the difference between pre-and post-grazing pasture DM biomass during grazing period. Data were analyzed using a completely randomized design, and orthogonal contrasts to compare feeding system effects (feedlot (FL) vs. grazing (GR)) and the linear or quadratic effects of FO in the feedlot. During winter (Table 1), FL animals exhibited greater ADG (1.07 vs. 0.59 kg/d, SE: 0.04, P < 0.0001) and better FG (4.90 vs. 6.42 kg DM/kg BW, SE: 0.14, P = 0.0002) compared to GR. These responses were the opposite during spring, with a worst FG observed for feedlot animals (33.59 vs. 18.80; SE: 1.80, P = 0.0007) due to lower ADG (0.21 vs. 0.48; SE: 0.07, P = 0.0007). Lower ADG in the FL group during spring was primarily explained by significant weight loss during the first two grazing weeks compared to GR (-0.46 vs. 0.44 kg/day, SE: 0.08, P < 0.001). However, over the entire winter-spring period, FL animals demonstrated greater ADG compared to GR (0.68 vs. 0.56 kg/day, SE: 0.05, P = 0.0092) and better FG (10.71 vs. 9.65 kg DM/kg LW, SE: 0.36 P = 0.0508). Within the FL group during the winter-spring period, ADG increased linearly with FO (P = 0.0196), though no significant differences were observed in FG (P = 0.0916). No quadratic significant effects were found for any of the variables analyzed. Results evidence that over the entire winter-spring period, FL animals showed higher overall ADG and FG compared to grazing animals. Additionally, increasing FO linearly improved ADG and final BW by the end of spring.

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饲养场饲养水平对冬春期动物生长和饲料效率的影响

本研究评价了冬季背景饲喂制度（放牧与饲养场）和饲养场供料量对整个冬春期（182 d）平均日增重（ADG）和料重比（FG）的影响。选取体重（159±25 kg）的赫里福德母犊牛40头，在冬季（98 d）随机分为5个处理：每100 kg BW饲喂5 kg干物质（DM）的冬季草地放牧，或饲喂不同油重（2.2%、2.5%、2.9%和3.2% BW / DM）的饲料混合日粮（70%精料/ 30%粗料）。春季（84 d），各处理以周为块（n = 2块/处理）放牧混合牧草（6 kg DM/100 kg BW, 2524±880 kg DM/ha）。每14 d记录体重。每天在饲养场测量DMI，并以偶数周为单位估算放牧期间放牧前后牧场DM生物量的差异。采用完全随机设计对数据进行分析，并采用正交对比法比较饲养系统效应（饲养场（FL）与放牧（GR））和放牧区（FO）在饲养场的线性或二次效应。在冬季（表1），FL动物表现出更高的平均日增重(1.07 vs. 0.59 kg/d, SE: 0.04, P <；0.0001)和更好的成活率（4.90 vs. 6.42 kg DM/kg BW, SE: 0.14, P = 0.0002）。春季的情况正好相反，饲养场动物的成活率最差(33.59 vs. 18.80；SE: 1.80, P = 0.0007)，原因是平均日增重较低(0.21 vs. 0.48；Se: 0.07, p = 0.0007)。春季FL组平均日增重较低的主要原因是放牧前两周与GR组相比体重明显减轻(-0.46 vs. 0.44 kg/d, SE: 0.08, P <；0.001)。然而，在整个冬春期间，FL动物的平均日增重高于GR(0.68比0.56 kg/d, SE: 0.05, P = 0.0092)， FG（10.71比9.65 kg DM/kg LW, SE: 0.36 P = 0.0508）。冬春期，鱼粉组平均日增重随鱼油呈线性增加（P = 0.0196），而鱼粉组无显著差异（P = 0.0916）。所分析的任何变量均未发现二次显著效应。结果表明，在整个冬春期，放牧动物的平均日增重和净重均高于放牧动物。此外，增加鱼油可线性提高春季末日增重和末体重。

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来源期刊

Journal of animal science 农林科学-奶制品与动物科学

CiteScore

4.80

自引率

12.10%

发文量

1589

审稿时长

3 months

期刊介绍： The Journal of Animal Science (JAS) is the premier journal for animal science and serves as the leading source of new knowledge and perspective in this area. JAS publishes more than 500 fully reviewed research articles, invited reviews, technical notes, and letters to the editor each year. Articles published in JAS encompass a broad range of research topics in animal production and fundamental aspects of genetics, nutrition, physiology, and preparation and utilization of animal products. Articles typically report research with beef cattle, companion animals, goats, horses, pigs, and sheep; however, studies involving other farm animals, aquatic and wildlife species, and laboratory animal species that address fundamental questions related to livestock and companion animal biology will be considered for publication.