Abdelsattar Mahmoud, Zhuang Yimin, Cui Kai, Bi Yanliang, Zhang Naifeng
Key Laboratory of Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Department of Animal and Poultry Production, Faculty of Agriculture, South Valley University, 83523 Qena, Egypt.
Animals (Basel). 2021 Mar 10;11(3):757. doi: 10.3390/ani11030757.
The transition from monogastric to rumination stage is crucial in ruminants' growth to avoid stressors-weaning and neonatal mortalities. Poor growth of the digestive tract could adversely affect the performance of the animal. Modeling informative growth curves is of great importance for a better understanding of the effective development pattern, in order to optimize feeding management system, and to achieve more production efficiency. However, little is known about the digestive tract growth curves. For this reason, one big goat farm of Laiwu black breed was chosen as a basis of this study. Forty-eight kids belonging to eight-time points (1, 7, 14, 28, 42, 56, 70, and 84 d; 6 kids for each) were selected and slaughtered. The body weight, body size indices, rumen pH, and stomach parts were determined and fitted to the polynomial and sigmoidal models. In terms of goodness of fit criteria, the Gompertz model was the best model for body weight, body oblique length, tube, and rumen weight. Moreover, the Logistic model was the best model for carcass weight, body height, and chest circumference. In addition, the Quadratic model showed the best fit for dressing percentage, omasum weight, abomasum weight, and rumen volume. Moreover, the cubic model best fitted the ruminal pH and reticulum percentage. The Weibull model was the best model for the reticulum weight and omasum percentage, while the MMF model was the best model describing the growth of chest depth, rumen percentage, and abomasum percentage. The model parameters, R squared, inflection points, area under curve varied among the different dependent variables. The Pearson correlation showed that the digestive tract development was more correlated with age than body weight, but the other variables were more correlated with body weight than age. The study demonstrated the use of empirical sigmoidal and polynomial models to predict growth rates of the digestive tract at relevant age efficiently.
从单胃到反刍阶段的转变对于反刍动物的生长至关重要，可避免应激源——断奶和新生仔畜死亡。消化道生长不良会对动物的生产性能产生不利影响。建立信息丰富的生长曲线模型对于更好地理解有效发育模式、优化饲养管理系统以及提高生产效率具有重要意义。然而，关于消化道生长曲线的了解却很少。因此，本研究选取了莱芜黑山羊的一个大型养殖场作为研究基础。选取了48只处于八个时间点（1、7、14、28、42、56、70和84日龄；每个时间点6只）的羔羊并进行屠宰。测定了体重、体尺指标、瘤胃pH值和胃各部分的情况，并将其拟合到多项式模型和S形模型。就拟合优度标准而言，Gompertz模型是体重、体斜长、管和瘤胃重量的最佳模型。此外，Logistic模型是胴体重、体高和胸围的最佳模型。另外，二次模型对屠宰率、瓣胃重量、皱胃重量和瘤胃容积的拟合效果最佳。此外，三次模型对瘤胃pH值和网胃比例的拟合效果最佳。Weibull模型是网胃重量和瓣胃比例的最佳模型，而MMF模型是描述胸深、瘤胃比例和皱胃比例生长的最佳模型。模型参数、决定系数、拐点、曲线下面积在不同的因变量之间有所不同。Pearson相关性分析表明，消化道发育与年龄的相关性高于与体重的相关性，但其他变量与体重的相关性高于与年龄的相关性。该研究证明了使用经验性S形模型和多项式模型能够有效地预测相关年龄阶段消化道的生长速率。
