Piglets experience a rapid decrease in body temperature immediately after birth, increasing the risk of mortality. The objective of this study was to determine the effect of drying and/or warming piglets at birth on rectal temperature over the first 24 h after birth. The study was carried out at a commercial sow facility using a completely randomized design with 4 treatments (applied to piglets at birth): Control (no drying or warming), Desiccant (dried using a desiccant), Warming Box (placed in a box under a heat lamp for 30 min), and Desiccant+Warming Box (both dried and warmed as above). Farrowing pens had one heat lamp, temperatures under which were similar to the warming box (35°C). A total of 68 litters (866 piglets) were randomly allotted to a treatment at the birth of the first piglet. At birth, each piglet was identified with a numbered ear tag and weighed; rectal temperature was measured at 0, 10, 20, 30, 45, 60, 120, and 1440 min after birth. Data were analyzed using a repeated measures model using PROC MIXED of SAS. Litter was the experimental unit, piglet was a subsample of the litter; the model included the fixed effects of treatment, time (the repeated measure), and the interaction. Rectal temperatures at birth and 1440 min after birth were similar (P > 0.05) for all treatments. At all times between 10 and 120 min after birth, Control piglets had lower (P ≤ 0.05) temperatures than the other 3 treatments. The Desiccant and Warming Box treatments had similar (P > 0.05) temperatures at most measurement times, but the Desiccant+Warming Box treatment had the highest (P ≤ 0.05) rectal temperatures at most times between 10 and 60 min. In addition, for all treatments, Light (< 1.0 kg) birth weight piglets had lower (P ≤ 0.05) temperatures than Medium (1.0 to 1.5 kg) or Heavy (> 1.5 kg) piglets at all times between 10 and 120 min. In addition, at these measurement times, the deviation in temperature between the Control and the other 3 treatments was greater for Light than Medium or Heavy piglets. In conclusion, both drying and warming piglets at birth significantly increased rectal temperatures between 10 and 120 min after birth, with the combination of the 2 interventions having the greatest effect, especially for low birth weight piglets.

The objective of this study was to evaluate the effects of piglet birth weight and drying piglets at birth on post-natal rectal temperatures using a CRD with 2 treatments: 1) Drying (not dried vs. dried at birth with a desiccant); 2) Birth weight [4 within-litter birth weight quartiles (Q1: 1.13 ± 0.33 kg, Q2: 1.43 ± 0.28 kg, Q3: 1.62 ± 0.28 kg, Q4: 1.81 ± 0.28 kg)]. Sows (26) and litters (281 piglets) were randomly allotted to drying treatment and were housed in farrowing crates with a heat lamp; room temperature was set at 22.8°C. Piglets were weighed at birth and rectal temperature measured at 0, 15, 30, 45, 60, 90, 120, 180, 240, and 1440 min after birth. Data were analyzed using PROC MIXED of SAS (SAS Inst. Inc., Cary, NC); the model included fixed effects of litter birth weight quartile and drying treatment and interaction, and time (repeated measure), and random effect of sow. Mean piglet birth weight and rectal temperature at birth were 1.49 ± 0.39 kg and 39.2 ± 0.43°C, respectively. There were no drying by birth weight treatment interactions. Temperatures were similar (P > 0.05) for the drying and birth weight treatments at birth and 240 and 1440 min (Table 1). Drying increased (P < 0.05) rectal temperature from 15 to 180 min; the greatest difference was at 45 min (2.4°C). Temperatures were similar (P > 0.05) for Q2, 3, and 4 from 15 to 180 min. Quartile 1 had a lower (P < 0.05) temperature than the 3 heavier quartiles from 15 to 180 min, except at 120 min when temperatures were similar for Q1 and 2. The lightest piglets exhibited the greatest post-natal temperature decline and drying of piglets at birth reduced the post-natal temperature decline in piglets of all weights.

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.

Piglets are born wet, and evaporation of that moisture decreases body temperature, increasing the risk of mortality. The objective of this study was to compare the effect of 2 commercially-applicable methods for drying piglets at birth on piglet rectal temperature over 24 h after birth. The study was carried out in standard commercial farrowing facilities with 52 litters, using a completely randomized design with 3 Drying Treatments: Control (not dried); Desiccant (dried at birth using a cellulose-based desiccant); Paper Towel (dried at birth using paper towels). Litters were randomly allotted to treatments at the birth of the first piglet. At birth, piglets were individually identified, and the treatment was applied. Rectal temperature was measured at 0, 10, 20, 30, 45, 60, 120, and 1440 min (24 h) after birth. Data were analyzed using a repeated measures model with PROC MIXED of SAS, with litter as the experimental unit and piglet a subsample of the litter. The model included the fixed effects of treatment and time (as a repeated measure), and the interaction. There was no effect (P > 0.05) of treatment on temperature at birth, or 10 or 1440 min after birth. Piglet temperatures between 20 and 120 min after birth were similar (P > 0.05) for the Desiccant and Paper Towel treatments, but were greater (P ≤ 0.05) than the Control. The effect of birth weight on the response to Drying Treatment was evaluated by dividing the data into Light (< 1.0 kg), Medium (1.0 to 1.5 kg), or Heavy (> 1.5 kg) piglet Birth Weight Categories. Piglet rectal temperature data at each measurement time were analyzed using a model that included the fixed effects of Birth Weight Category, Drying Treatment, and the interaction. Temperatures of Light piglets were lower (P ≤ 0.05) than those of Heavy piglets between 20 and 120 min after birth, with Medium piglets being intermediate and generally different to the other 2 weight categories at these times. The difference in temperature between Light as compared to Medium or Heavy piglets was greater for the Control than the other 2 Drying Treatments at 60 min after birth. These results suggest that drying piglets at birth is an effective method to reduce rectal temperature decline in the early post-natal period, especially for low birth weight piglets.

Cross-fostering is a practice commonly used in the swine industry to equalize litter sizes, however, there is limited understanding of the optimum cross-fostering methods that will maximize piglet pre-weaning growth and survival. This study evaluated the effects of within-litter variation in birth weight after cross-fostering on piglet pre-weaning mortality (PWM) and weaning weight (WW) using litters of 15 piglets. A hierarchical incomplete block design was used (blocking factors: day of farrowing and sow parity, body condition score, and number of functional teats) with a 3 by 2 factorial arrangement of 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 15 piglets in each litter of the same BWC), or MIXED (5 piglets in each litter from each BWC; i.e., 5 Light, 5 Medium, and 5 Heavy piglets). At 24 h after birth, piglets were weighed and randomly allotted to Litter Composition treatments from within BWC. The experimental unit was five piglets of the same BWC; there were three experimental units within each Litter Composition treatment litter. There were 17 blocks, each of six litters (one UNIFORM litter of each BWC; three MIXED litters) and 51 replicates (three replicates per block of six litters) for a total of 102 cross-fostered litters and 1,530 piglets. Piglets were weaned at 19.7 ± 0.46 d of age; WW and PWM were measured. PROC GLIMMIX and MIXED of SAS were used to analyze PWM and WW, respectively. Models included BWC, Litter Composition, the interaction, and replicate within block. There were BWC by Litter Composition treatment interactions (P ≤ 0.05) for PWM and WW. Pre-weaning mortality was greater (P ≤ 0.05) for Light piglets in MIXED than UNIFORM litters. In contrast, for Heavy piglets PWM was greater (P ≤ 0.05) and WW was lower (P ≤ 0.05) in UNIFORM than MIXED litters. Medium piglets had similar (P > 0.05) PWM and WW in UNIFORM and MIXED litters. The results of this study, which involved large litter sizes typical of current commercial production, suggested that for piglet survival to weaning, using cross-fostering to form litters of piglets of similar birth weight was beneficial for Light piglets, detrimental for Heavy piglets, and neutral for Medium piglets.

There is limited understanding of optimum cross-fostering methods to use to maximize piglet performance. This study evaluated effects of within-litter birth weight variation after cross-fostering on pre-weaning piglet removals (PR; morbidity and mortality) and ADG. A hierarchical incomplete block design was used (blocking factors day of farrowing and sow parity and structure) with a 3x2 factorial arrangement of treatments: 1) Birth Weight Category (BWC): Light (< 1.0 kg), Medium (1.0-1.5 kg), or Heavy (1.5-2.0 kg); 2) Litter Composition (LC): Uniform (piglets of the same BWC), and Mixed (equal numbers of piglets from each BWC). Piglets were weighed 24 h after birth and allotted to form litters of 15 cross-fostered piglets. The experimental unit was 5 piglets of the same BWC (3 experimental units per litter). A total of 102 litters were allotted to 17 blocks of 6 litters (1 Uniform litter of each BWC; 3 Mixed litters) with 51 replicates (3 replicates/block of 6 litters). Weaning weights and PR were measured. PROC GLIMMIX and MIXED of SAS were used to analyze PR and other data, respectively. Models included BWC, LC, the interaction, and replicate within block. There were treatment interactions (P < 0.05) for all measures except birth weight. There was no effect (P > 0.05) of LC on weaning weight or ADG for Light or Medium piglets; Heavy piglets had greater (P < 0.05) weaning weight and ADG in Mixed than in Uniform litters. PR were greater (P < 0.05) for Light piglets in Mixed than in Uniform litters, and for Heavy piglets in Uniform than in Mixed litters. PR for Medium piglets were similar (P > 0.05) across LC treatments. In conclusion, rearing cross-fostered piglets in Uniform litters reduced PR for Light piglets, but increased PR and reduced ADG of Heavy piglets, with no effect for Medium piglets.

Neonatal piglets can experience both a decrease in body temperature and hypoxia, increasing risks for pre-weaning mortality. This research evaluated the effects of drying and providing supplemental oxygen to newborn piglets on rectal temperature (RT) over the first 24 h after birth. The study used a CRD with 3 Intervention Treatments (IT; applied at birth): Control (no intervention), Drying (dried using a desiccant), Oxygen [dried using a desiccant and placed in a chamber (at 40% oxygen concentration) for 20 min]. A total of 42 litters (485 piglets) were randomly allotted to treatments at the start of farrowing. At birth, each piglet was given a numbered ear tag, weighed, and the treatment was applied; RT was measured at 0, 20, 30, 45, 60, 120, and 1440 min after birth. Blood was collected from one piglet from each birth weight quartile within each litter at 24 h after birth to measure plasma immunocrit concentration. There was no effect (P > 0.05) of IT on piglet RT at 0 or 1440 min after birth. Between 20 and 60 min after birth, piglet RT was lower (P ≤ 0.05) for the Control than the Drying treatment, with the Oxygen treatment being intermediate and different (P ≤ 0.05) from the other two IT. The effect of piglet birth weight on responses to IT were evaluated by classifying piglets into Birth Weight Categories (BWC): Light (< 1.0 kg), Medium (1.0 to 1.5 kg), or Heavy (> 1.5 kg). There were IT by BWC interactions (P ≤ 0.05) for piglet RT at all measurement times between 20 and 120 min after birth. Relative to the Control, the effects of the Drying and Oxygen treatments on RT were greater (P ≤ 0.05) for Light than heavier piglets. Plasma immunocrit concentrations tended (P = 0.07) to be greater for piglets on the Control treatment compared to the other two IT and were lower (P ≤ 0.05) for Light than Heavy piglets, with Medium piglets being intermediate and different (P ≤ 0.05) to the other BWC. In conclusion, drying piglets at birth reduced the extent and duration of RT decline in piglets in the early postnatal period compared to undried piglets, especially for those of low birth weight. However, the combination of drying and placing piglets in an oxygen-rich environment provided no additional benefit over drying alone.

Litter sizes of commercial sows have increased considerably over recent decades, and often exceed the number of functional teats on the sow. The objective of this study was to evaluate the effect of litter size after cross-fostering relative to sow functional teat number on piglet preweaning growth and mortality. A total of 39 litters (561 piglets) were used in a randomized complete block design; blocking factors were farrowing day and sow parity, body condition score, and functional teat number. Three Litter Size treatments were compared (relative to sow functional teat number): Decreased (two piglets less); Control (same number of piglets); Increased (two piglets more). Piglets were randomly allotted to treatment at 24 h after birth to form litters of the appropriate size, with similar mean and CV of birth weight within block. Weaning weights (WW) were collected at 19.5 ± 0.50 d of age; preweaning mortality (PWM) was recorded. Litter sizes were between 11 and 17 piglets, depending on block and treatment. The Decreased treatment had lower (P ≤ 0.05) PWM than the Increased (7.7% and 17.9%, respectively); the Control was intermediate (11.5%) and not different (P > 0.05) from the other treatments. The rate of decline in litter size from birth to weaning was greater (P ≤ 0.05) for the Increased than the Decreased treatment (−0.16 vs. −0.05 piglets per day), with the Control (−0.09 piglets per day) being intermediate and different (P ≤ 0.05) to the other two treatments. Litter sizes at weaning were greater (P ≤ 0.05) for the Increased than the Decreased treatment (13.3 and 11.3, respectively); the Control treatment was intermediate (12.6) and not different (P > 0.05) to the other treatments. The log odds of PWM increased with the decreasing birth weight, at a similar rate (P > 0.05) for all Litter Size treatments. However, the intercept was greater (P ≤ 0.05) for the Increased compared with the Decreased treatment; the Control was intermediate and different (P > 0.05) to the other two treatments. Mean WW tended (P = 0.07) to be greater for the Decreased (6.17 kg) compared to the Control and Increased treatments (5.86 and 5.84 kg, respectively). In conclusion, increasing litter size after cross-fostering relative to the number of functional teats of the sow increased piglet PWM, and tended to decrease WW.