Effect of within-litter birth weight variation after cross-fostering on piglet preweaning growth and mortality

Abstract

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 effects of within-litter birth weight variation after cross-fostering (using litters of 14 piglets) on piglet pre-weaning mortality (PWM) and weaning weight (WW). A 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 (7 Light and 7 Medium piglets); M+H (7 Medium and 7 Heavy piglets); L+M+H (3 Light, 6 Medium, and 5 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 6 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 block. There were Litter Composition by BWC interactions (P ≤ 0.05) for WW and PWM. Within each BWC, WW generally increased and PWM generally decreased as littermate weight decreased. For example, WW were greatest (P ≤ 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. Pre-weaning mortality was lowest (P ≤ 0.05) for Medium piglets in L+M litters, and for Heavy piglets in L+M+H litters; however, Litter Composition had no effect (P > 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 pre-weaning growth and survival is likely to vary depending on the birth weight distribution of the population.

Effect of farrowing pen size on pre-weaning performance of piglets

“…Sow parameters (i.e., parity, body condition score, and total teat number) were similar ( P > 0.05) for the two treatments. Body condition scores and teat numbers were comparable to those reported for contemporary commercial sow populations ( Maes et al, 2004 ; Kim et al, 2005 ; Vande Pol et al, 2021a , b ). The average parity of sows used in the current study was relatively low (2.7) compared to that typically observed in commercial herds ( Maes et al, 2004 ; Vande Pol et al, 2021a , b ).…”

“…Body condition scores and teat numbers were comparable to those reported for contemporary commercial sow populations ( Maes et al, 2004 ; Kim et al, 2005 ; Vande Pol et al, 2021a , b ). The average parity of sows used in the current study was relatively low (2.7) compared to that typically observed in commercial herds ( Maes et al, 2004 ; Vande Pol et al, 2021a , b ). The unit used for this study was repopulated with first litter gilts at the start of the study, resulting in a relatively greater proportion of sows with low parities than would typically be observed.…”

“…These results indicate that there was no benefit from increasing farrowing pen size for piglet performance. A factor that could influence the effect of farrowing pen size is the parity number of the sows, which was relatively low in the current study (2.7) compared to that commonly observed on commercial farms ( Maes et al, 2004 ; Vande Pol et al, 2021a , b ). Litter sizes at birth generally increase with parity up to approximately the fifth parity ( Lavery et al, 2018 ).…”

“…The highest levels of pre-weaning mortality generally occur in the first few days after birth ( Su et al, 2007 ) with the primary cause being due to crushing by the sow ( Dyck and Swierstra, 1987 ; Vande Pol et al, 2021a , b ). The current study was based on the premise that increasing the size of the farrowing pen would increase the distance between the piglets and the sow, thereby reducing the likelihood of piglets being crushed.…”

“…Despite this increase in the number of piglets per litter, farrowing pen sizes used on commercial operations have generally not changed and are based on historical recommendations (e.g., Midwest Plan Service, 1991 ). In addition, the primary cause of piglet pre-weaning mortality under commercial conditions continues to be crushing by the sow ( Vande Pol et al, 2021a , b ). Conceptually, increasing the size of farrowing pens could reduce the risk of piglets being crushed by providing more space to avoid the sow.…”