Silva Flávio G, Carreira Emanuel, Ramalho Joana M, Correia Tomás, Meira Marília, Conceição Cristina, Silva Severiano R, Pereira Alfredo M F, Cerqueira Joaquim L
Veterinary and Animal Research Centre (CECAV) and Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), Department of Animal Science, Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
MED-Mediterranean Institute for Agriculture, Environment and Development and CHANGE-Global Change and Sustainability Institute, Universidade de Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal.
Animals (Basel). 2024 Jul 21;14(14):2129. doi: 10.3390/ani14142129.
Regularly weighing calves helps to assess the efficiency of the rearing period and contributes to animal welfare by allowing more precise feeding and medication application in dairy farming, but many farmers do not weigh their calves regularly. Improving the feasibility of this process is, therefore, important. The use of morphometric measurements has been used to estimate the weight of cattle. However, many studies have focused on adult animals or used a wide age range. As calves experience allometric tissue growth, specific models for certain ranges might be more accurate. Therefore, the aim of this work was to develop a weight estimation model specific for pre-weaned Holstein-Friesian calves using morphometric measurements and to compare the model with another equation previously validated for the same breed with young and adult animals. From four dairy farms, 237 measurements of body weight, heart girth, abdominal girth, hip height, withers height, and body length were taken from Holstein-Friesian male and female calves. Linear and non-linear regression analysis was used to test the relationship between body weight and morphometric measurements, with age, sex, and farm as possible explanatory variables. Selected models were compared with goodness of fit and agreement tests. The final model was able to accurately predict body weight (R = 0.96) with a mean difference of -1.4 ± 3.24 kg. Differences in the relationship between body weight and morphometric traits were observed between farms, but not between males and females. The genetics of the animal population at farm level may be responsible for this variability and further studies are needed to understand this variability and improve weight prediction models. The developed model was able to perform better in the agreement tests than the previously validated model for Holstein-Friesian animals, suggesting that different equations should be used depending on the growth phase the animal is in. In addition, a web application has been developed to facilitate the use of the developed model by farmers. This avoids the use of calibrated weight bands, which are usually calibrated for a broader age range or for beef cattle.
定期称量犊牛体重有助于评估育犊期的效率，并且通过在奶牛养殖中实现更精确的喂养和用药，有助于动物福利，但许多养殖户并不定期称量犊牛体重。因此，提高这一过程的可行性很重要。形态测量法已被用于估算牛的体重。然而，许多研究聚焦于成年动物或使用了较宽的年龄范围。由于犊牛经历异速生长，针对特定范围的特定模型可能更准确。因此，本研究的目的是利用形态测量法开发一个针对断奶前荷斯坦-弗里生犊牛的体重估计模型，并将该模型与之前针对同一品种的青年和成年动物验证过的另一个公式进行比较。从四个奶牛场选取了237头荷斯坦-弗里生公母犊牛，测量了它们的体重、胸围、腹围、臀高、鬐甲高和体长。使用线性和非线性回归分析来检验体重与形态测量值之间的关系，并将年龄、性别和养殖场作为可能的解释变量。通过拟合优度检验和一致性检验对所选模型进行比较。最终模型能够准确预测体重（R = 0.96），平均差值为-1.4 ± 3.24千克。各养殖场之间观察到体重与形态特征之间的关系存在差异，但公母之间没有差异。养殖场层面动物群体的遗传因素可能是造成这种变异性的原因，需要进一步研究以了解这种变异性并改进体重预测模型。所开发的模型在一致性检验中的表现优于之前针对荷斯坦-弗里生动物验证过的模型，这表明应根据动物所处的生长阶段使用不同的公式。此外，还开发了一个网络应用程序，以方便养殖户使用所开发的模型。这避免了使用通常针对更宽年龄范围或肉牛校准的校准体重带。
