Vande Pol Katherine D, Bautista Rafael O, Harper Heath, Shull Caleb M, Brown Catherine B, Ellis Michael
Department of Animal Sciences, University of Illinois, Urbana-Champaign, IL 61801, USA.
The Maschhoffs, LLC, Carlyle, IL 62231, USA.
Transl Anim Sci. 2021 Mar 1;5(3):txab039. doi: 10.1093/tas/txab039. eCollection 2021 Jul.
Cross-fostering is commonly used in commercial swine production to equalize litter sizes and/or adjust piglet birth weights within litters. However, there is limited published information on optimum cross-fostering procedures. This study evaluated the effects of within-litter birth weight variation after cross-fostering (using litters of 14 piglets) on piglet preweaning mortality (PWM) and weaning weight (WW). An RCBD was used (blocking factors were day of farrowing and sow parity, body condition score, and functional teat number) with an incomplete factorial arrangement of the following two treatments: 1) birth weight category (BWC): light (<1.0 kg), medium (1.0 to 1.5 kg), or heavy (1.5 to 2.0 kg); 2) litter composition: uniform, all piglets in the litter of the same BWC [uniform light (14 light piglets); uniform medium (14 medium piglets); uniform heavy (14 heavy piglets)]; mixed, piglets in the litter of two or more BWC [L+M (seven light and seven medium piglets); M+H (seven medium and seven heavy piglets); L+M+H (three light, six medium, and five heavy piglets)]. Piglets were weighed at 24 h after birth and randomly allotted to litter composition treatment from within BWC; all piglets were cross-fostered. There were 47 blocks of six litters (total 282 litters and 3,948 piglets). Weaning weights were collected at 18.7 ± 0.64 d of age; all PWM was recorded. Individual piglet WW and PWM data were analyzed using PROC MIXED and PROC GLIMMIX of SAS, respectively; models included fixed effects of BWC, litter composition, and the interaction, and random effects of sow within the block. There was litter composition by BWC interactions ( ≤ 0.05) for WW and PWM. Within each BWC, WW generally increased and PWM generally decreased as littermate weight decreased. For example, WW was greatest ( ≤ 0.05) for light piglets in uniform light litters, for medium piglets in L+M litters, and for heavy piglets in L+M+H litters. Preweaning mortality was lowest ( ≤ 0.05) for medium piglets in L+M litters, and for heavy piglets in L+M+H litters; however, litter composition had no effect ( > 0.05) on PWM of light piglets. In conclusion, increasing the average birth weight of littermates after cross-fostering generally decreased WW and increased PWM for piglets of all birth weight categories. This implies that the optimum approach to cross-fostering that maximizes piglet preweaning growth and survival is likely to vary depending on the birth weight distribution of the population.
交叉寄养在商业养猪生产中普遍使用，目的是均衡窝产仔数和/或调整窝内仔猪出生体重。然而，关于最佳交叉寄养程序的公开信息有限。本研究评估了交叉寄养后（使用14头仔猪的窝）窝内出生体重差异对仔猪断奶前死亡率（PWM）和断奶体重（WW）的影响。采用随机区组设计（区组因素为产仔日、母猪胎次、体况评分和有效乳头数），对以下两种处理进行不完全析因安排：1）出生体重类别（BWC）：轻（<1.0千克）、中（1.0至1.5千克）或重（1.5至2.0千克）；2）窝组成：均匀，窝内所有仔猪出生体重类别相同[均匀轻（14头轻仔猪）；均匀中（14头中仔猪）；均匀重（14头重仔猪）]；混合，窝内仔猪出生体重类别为两种或更多[轻+中（7头轻仔猪和7头中仔猪）；中+重（7头中仔猪和7头重仔猪）；轻+中+重（3头轻仔猪、6头中仔猪和5头重仔猪）]。仔猪出生后24小时称重，并从相同出生体重类别内随机分配到窝组成处理组；所有仔猪均进行交叉寄养。共有47个区组，每个区组6窝（共282窝和3948头仔猪）。在18.7±0.64日龄时收集断奶体重；记录所有断奶前死亡率。分别使用SAS的PROC MIXED和PROC GLIMMIX对个体仔猪的断奶体重和断奶前死亡率数据进行分析；模型包括出生体重类别、窝组成及其交互作用的固定效应，以及区组内母猪的随机效应。断奶体重和断奶前死亡率存在出生体重类别与窝组成的交互作用（P≤0.05）。在每个出生体重类别内，随着同窝仔猪体重降低，断奶体重总体增加，断奶前死亡率总体降低。例如，均匀轻窝中的轻仔猪、轻+中窝中的中仔猪以及轻+中+重窝中的重仔猪断奶体重最高（P≤0.05）。轻+中窝中的中仔猪以及轻+中+重窝中的重仔猪断奶前死亡率最低（P≤0.05）；然而，窝组成对轻仔猪的断奶前死亡率没有影响（P>0.05）。总之，交叉寄养后提高同窝仔猪的平均出生体重通常会降低所有出生体重类别的仔猪断奶体重，并增加断奶前死亡率。这意味着，使仔猪断奶前生长和存活最大化的最佳交叉寄养方法可能因群体出生体重分布而异。
