Undegradable dietary protein limits growth and carcass yields in crossbred Boer kids fed Desmanthus hay or Rhodes grass (Chloris gayana) hay supplemented with urea and/or cottonseed meal

IF 1.4 4区农林科学 Q2 Agricultural and Biological Sciences

Animal Production Science Pub Date : 2024-09-09 DOI:10.1071/an23157

A. Aoetpah, C. Gardiner, B. Gummow, A. Mialon, G. Walker

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引用次数: 0

Abstract

Context

Low-protein tropical forages required protein supplementation, which might affect growth of meat goats.

Aims

This study was aimed to compare liveweight gain, carcass/non-carcass yields and meat quality in crossbred Boer kids fed isonitrogenous diets varying in undegradable (UDP) and rumen-degradable (RDP) dietary protein sources.

Methods

Twenty-five female crossbred Boer kids were randomly allocated into the following five dietary treatments: Rhodes grass (Chloris gayana) hay supplemented with urea (U), urea plus cottonseed meal (UCSM), cottonseed meal (CSM), gliricidia (Gliricidia sepium) (Gliri) or Desmanthus (Desmanthus leptophyllus) only (Desman). The diets were formulated to supply 135 and 195 g crude protein/kg DM for the two experiments. Experiment 1 lasted 78 days and the dietary UDP:RDP ratio (g/kg DM) was 35:102 (U), 37:100 (UCSM), 40:97 (CSM), 55:82 (Desman) and 46:91 (Gliri). Experiment 2 lasted 138 days and the dietary UDP:RDP ratio (g/kg DM) was 45:150 (U), 52:143 (UCSM), 58:137 (CSM), 83:112 (Desman) and 71:124 (Gliri) respectively. Data were subjected to one-way ANOVA and general linear model.

Key results

After 138 days of supplementation, the Desman goats had the highest liveweight gain (83 g/day) and heaviest cold carcass weight (12.1 kg) in Experiment 2. This was followed, in descending order, by CSM (58 g/day and 9.6 kg), UCSM (48 g/day and 7.8 kg), Gliri (41 g/day and 7.6 kg) and U (6 g/day and 6.0 kg). Heavier carcass weight was associated with larger eye-muscle area and fat depth at the 12th rib. Aus-meat Beef Colour Standard scores of 3–4 for the eye muscle of the Desman and CSM goats compared with scores of 1C-2 in the other goats meant that the darker meat in Desman and CSM diets was associated with heavier carcass weight and a more rapid rate of decline in carcass pH.

Conclusions

Crossbred Boer kids fed high dietary UDP had higher intakes of UDP, RDP, metabolisable protein (MP) and metabolisable energy (ME), even though an isonitrogenous diet was offered. The Desman kids had higher liveweight gain, heavier carcass yield, greater eye-muscle area, thicker fat depth and heavier mass of non-carcass components.

Implications

The higher liveweight gain and carcass/non-carcass yields for Desman goats than for others was associated with increased DM, UDP, RDP, MP and ME intakes.

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不可降解的日粮蛋白质限制了杂交波尔奶牛的生长速度和胴体产量，这些奶牛饲喂的是脱毒草（Desmanthus）干草或添加尿素和/或棉籽粕的罗得草（Chloris gayana）干草

背景低蛋白热带饲草需要补充蛋白质，这可能会影响肉用山羊的生长。目的：本研究旨在比较杂交波尔山羊饲喂不同不可降解（UDP）和瘤胃可降解（RDP）膳食蛋白质来源的等氮日粮的活重增加、胴体/非胴体产量和肉质。方法将 25 头雌性杂交波尔牛随机分配到以下 5 种日粮处理中：罗得草（Chloris gayana）干草辅以尿素（U）、尿素加棉籽粕（UCSM）、棉籽粕（CSM）、鹅掌楸（Gliricidia sepium）（Gliri）或仅鹅掌楸（Desmanthus leptophyllus）（Desman）。两次实验的日粮配方分别为 135 和 195 克粗蛋白/千克 DM。实验 1 历时 78 天，日粮中 UDP 与 RDP 的比例（克/千克 DM）分别为 35:102（U）、37:100（UCSM）、40:97（CSM）、55:82（Desman）和 46:91（Gliri）。实验 2 历时 138 天，日粮中 UDP 与 RDP 的比例（克/千克 DM）分别为 45:150（U）、52:143（UCSM）、58:137（CSM）、83:112（Desman）和 71:124（Gliri）。数据采用单因素方差分析和一般线性模型。主要结果在实验 2 中，补充 138 天后，德斯曼山羊的活重增重（83 克/天）最高，冷胴体重量（12.1 千克）最重。其次依次是 CSM（58 克/天，9.6 千克）、UCSM（48 克/天，7.8 千克）、Gliri（41 克/天，7.6 千克）和 U（6 克/天，6.0 千克）。较重的胴体与较大的眼肌面积和第 12 根肋骨处的脂肪深度有关。Desman 和 CSM 山羊眼肌的澳肉牛肉颜色标准分数为 3-4 分，而其他山羊的分数为 1C-2 分，这意味着 Desman 和 CSM 日粮中颜色较深的肉与较重的胴体重量和较快的胴体 pH 值下降速度有关。结论饲喂高日粮 UDP 的杂交波尔山羊幼崽的 UDP、RDP、可代谢蛋白 (MP) 和可代谢能 (ME) 摄入量较高，即使提供的是等氮日粮。Desman 孩子的活重增重更高、胴体产量更高、眼肌面积更大、脂肪深度更厚、非胴体成分的质量更重。说明与其他山羊相比，德斯曼山羊的活重增重和胴体/非胴体产量较高与DM、UDP、RDP、MP和ME摄入量增加有关。

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来源期刊

Animal Production Science Agricultural and Biological Sciences-Food Science

CiteScore

3.00

自引率

7.10%

发文量

139

审稿时长

3-8 weeks

期刊介绍： Research papers in Animal Production Science focus on improving livestock and food production, and on the social and economic issues that influence primary producers. The journal (formerly known as Australian Journal of Experimental Agriculture) is predominantly concerned with domesticated animals (beef cattle, dairy cows, sheep, pigs, goats and poultry); however, contributions on horses and wild animals may be published where relevant. Animal Production Science is published with the endorsement of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Academy of Science.