Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506.
Department of Animal Science, Oklahoma State University, Stillwater, OK.
J Anim Sci. 2019 Dec 17;97(12):4770-4782. doi: 10.1093/jas/skz354.
In the future, water may not be as readily available due to increases in competition from a growing human population, wildlife, and other agricultural sectors, making selection for water efficiency of beef cattle increasingly important. Substantial selection emphasis has recently been placed on feed efficiency in an effort to reduce production costs, but no emphasis has been placed on making cattle more water efficient due to lack of data. Thus, the objective of this study was to calculate water efficiency metrics for cattle and evaluate their relationship to growth, feed intake (FI), and feed efficiency. Individual daily FI and water intake (WI) records were collected on 578 crossbred steers over a 70-d test period. Animals with low water intake ate less feed, had lower gains, and were more water efficient (as defined by water to gain ratio, W/G, and residual water intake, RWI). However, the amount of water consumed by animals had minimal phenotypic relationship with feed efficiency (residual feed intake [RFI], R2 = 0.1050 and feed to gain ratio (F/G) ratio R2 = 0.0726). Cattle that had low DMI consumed less water, had lower gains, had lower RFI, and had higher F/G. The level of feed consumed had minimal relationship with water efficiency. WI, W/G, RWI, and ADG had moderate heritability estimates of 0.39, 0.39, 0.37, and 0.37, respectively. High heritability estimates were observed for DMI and RFI (0.67 and 0.65, respectively). Feed to gain had a low heritability estimate of 0.16. WI had a strong positive genetic correlation with W/G (0.99) and RWI (0.88), thus selecting for decreased WI should also make cattle more water efficient. The genetic correlation between WI and ADG was 0.05; thus, selecting for low WI cattle should have little effect on growth. There is a low to moderate genetic correlation between WI and DMI (0.34). RWI has a positive genetic correlation with W/G ratio (0.89) and F/G ratio (0.42) and is negatively genetically correlated with RFI (-0.57). Water to gain and F/G had a strong positive genetic correlation (0.68). RFI has a positive genetic correlation with W/G ratio (0.37) and F/G (0.88). Minimal antagonisms seem to be present between WI and ADG, although it should be noted that standard errors were large and often not significantly different from zero due to the small sample size. However, care should be taken to ensure that unintended changes do not occur in DMI or other production traits and incorporation of WI into a selection index would likely prove to be the most effective method for selection.
在未来，由于人口增长、野生生物和其他农业部门的竞争增加，水的供应可能不会像现在这样充足，因此选择具有更高水效率的肉牛变得越来越重要。最近，人们为了降低生产成本，大量关注饲料效率，但由于缺乏数据，并没有关注提高牛的水效率。因此，本研究的目的是计算肉牛的水效率指标，并评估其与生长、采食量（FI）和饲料效率的关系。在 70 天的试验期间，对 578 头杂交公牛进行了个体日采食量（FI）和饮水量（WI）记录。低饮水量的动物采食量少，生长速度慢，水效率更高（用水增重比（W/G）和残留饮水量（RWI）定义）。然而，动物的耗水量与饲料效率（残留饲料摄入量[RFI]，R2=0.1050 和饲料增重比（F/G）比 R2=0.0726）的表型关系很小。低 DMI 的牛耗水量少，生长速度慢，RFI 低，F/G 高。饲料消耗量与水效率的关系很小。WI、W/G、RWI 和 ADG 的遗传力估计值分别为 0.39、0.39、0.37 和 0.37。DMI 和 RFI 的遗传力估计值较高（分别为 0.67 和 0.65）。饲料增重的遗传力估计值较低（0.16）。WI 与 W/G（0.99）和 RWI（0.88）具有很强的正遗传相关，因此选择减少 WI 也应该使牛更具水效率。WI 与 ADG 的遗传相关系数为 0.05；因此，选择低 WI 的牛对生长的影响应该很小。WI 与 DMI 的遗传相关系数较低（0.34）。RWI 与 W/G 比（0.89）和 F/G 比（0.42）呈正遗传相关，与 RFI（-0.57）呈负遗传相关。水增重和 F/G 具有很强的正遗传相关性（0.68）。RFI 与 W/G 比（0.37）和 F/G（0.88）具有正遗传相关性。WI 与 ADG 之间似乎存在较小的拮抗作用，尽管应注意到，由于样本量小，标准误差较大，并且经常与零无显著差异。然而，应该注意确保在 DMI 或其他生产性状中不会发生意外变化，并且将 WI 纳入选择指数可能是最有效的选择方法。
