Bila Lubabalo, Tyasi Thobela Louis, Fourie Pieter, Katikati Aphiwe
Faculty of Health and Environmental Sciences, Central University of Technology, Bloemfontein, South Africa.
Potchefstroom College of Agriculture, Department of Animal Production, Potchefstroom, South Africa.
J Adv Vet Anim Res. 2021 Mar 10;8(1):164-172. doi: 10.5455/javar.2021.h499. eCollection 2021 Mar.
The objective of this study was to assess the relationship between pelvic measurements, namely pelvic height (PH), pelvic area (PA), and pelvic width, and linear body measurement traits, such as hindquarters width, rump length (RL), hip height (HH), body weight (BW), shoulder height, chest depth (CD), body length, and also calve birth weight (CBW) under different calving ease scores, namely no assistance, gently pull, and hard pull.
A total of 51 first calf Sussex heifers at 24 months old, weighing approximately 440 ± 40.26 kg, were used for this study. Two-year-old bulls ( = 2), weighing approximately 800 kg, were used for mating the 51 heifers with a bull to cow ratio of 1:30 and 1:21. The fertility of bulls was assessed by a private veterinarian before the mating season. Calving ease was scored as follows: 1 = no assistance during parturition (normal), 2 = heifer assistance as gently pull, 3 = heifer assistance as hard pull, 4 = heifer cannot calf, 5 = heifer calved a dead calf, and 6 = heifer calf with the abnormal position.
Descriptive statistics indicated that PH ( < 0.01) and RL ( < 0.05) were positively remarkable and different among calving ease scores. Correlation results of the no assistance Sussex heifers group revealed that CBW was positively correlated ( < 0.05) with PH. Classification and regression tree CART results demonstrated that PH, BW, CD, and HH play an important role in predicting calving ease in Sussex heifers.
The findings suggest that there is an association among PAs and biometric traits. The present study might help farmers select animals with higher PH, BW, CD, and HH during breeding to lower dystocia incidents during parturition. However, further studies need to be carried out in CART modeling to reduce dystocia in a larger sample size of Sussex heifers or other cattle breeds.
本研究的目的是评估骨盆测量值，即骨盆高度（PH）、骨盆面积（PA）和骨盆宽度，与线性身体测量性状之间的关系，这些线性身体测量性状包括后躯宽度、臀长（RL）、髋高（HH）、体重（BW）、肩高、胸深（CD）、体长，以及在不同产犊难易评分（即无需协助、轻轻牵拉和用力牵拉）下的犊牛出生体重（CBW）。
本研究共使用了51头24月龄的初产苏塞克斯小母牛，体重约440±40.26千克。使用两头体重约800千克的两岁公牛，以1:30和1:21的公牛与母牛比例与这51头小母牛进行配种。在配种季节前，由一名私人兽医评估公牛的生育能力。产犊难易程度评分如下：1 = 分娩时无需协助（正常），2 = 小母牛协助且为轻轻牵拉，3 = 小母牛协助且为用力牵拉，4 = 小母牛无法产犊，5 = 小母牛产下死胎，6 = 小母牛犊牛胎位异常。
描述性统计表明，PH（P<0.01）和RL（P<0.05）在产犊难易评分之间存在显著正相关且有所不同。无需协助的苏塞克斯小母牛组的相关结果显示，CBW与PH呈正相关（P<0.05）。分类与回归树（CART）结果表明，PH、BW、CD和HH在预测苏塞克斯小母牛的产犊难易程度方面发挥着重要作用。
研究结果表明，PA与生物特征性状之间存在关联。本研究可能有助于养殖户在育种过程中选择具有较高PH、BW、CD和HH的动物，以降低分娩时难产事件的发生率。然而，需要对CART模型进行进一步研究，以在更大样本量的苏塞克斯小母牛或其他牛品种中减少难产情况。
