ABSTRACT We aimed to estimate litter size and litter uniformity genetic parameters and genetic trends of Landrace pigs at birth and at three weeks by using multitrait analyses for 2,787 litters. The following litter traits were evaluated: number of piglets born alive (NBA), within-litter weight mean at birth (MBW), within-litter weight standard deviation at birth (SDB), within-litter weight coefficient of variation at birth (CVB), number of piglets at three weeks (NT), within-litter weight mean at three weeks (MT), within-litter weight standard deviation at three weeks (SDT), and within-litter weight coefficient of variation at three weeks (CVT). Heritability estimates for NBA, MBW, SDB, and CVB were 0.09±0.04, 0.31±0.08, 0.01±0.04, and 0.07±0.05, respectively, greater than those obtained at three weeks (0.06±0.04, 0.10±0.06, 0.01±0.04, and 0.02±0.04 for NT, MT, SDT, and CVT, respectively). The genetic correlations between NBA and MBW and between MBW and CVB (−0.73±0.20 and −0.93±0.21, respectively) were of moderate to high magnitudes, as well as the genetic correlations between CVT and SDT (0.85±0.39). Genetic correlations between MBW and MT, SDB and SDT, CVB and CVT, and NBA and NT were 0.73±0.16, 0.69±0.54, 0.36±0.80, and 0.95±0.06, respectively. The genetic trends were linear for NBA and CVB and quadratic for MBW and SDB, whereas for all traits at three weeks, they were close to zero. Within-litter weight coefficient of variation (CV) may be the most appropriate variation measure for application in breeding programs, especially at birth, due to its greater heritability estimate and high and negative genetic correlation with MBW. The genetic trends show that NT does not follow the increase in NBA, emphasizing the need to review the breeding goals.

Abstract We aimed to evaluate the effects of paternal genotypes (Piau, Duroc-based, and Pietrain) and nutritional plans with different digestible lysine contents (Low, Medium, and High) on performance, carcass, and meat quality traits of pigs. Pietrain and Duroc crossbred barrows and gilts were similar in performance and carcass traits and had the greatest values when compared to Piau crossbred pigs. Regarding meat quality, drip loss was greater in pork from Pietrain crossbred barrows and gilts compared to Duroc and Piau crossbred pigs. The High nutritional plan had the greatest daily digestible lysine intake value, followed by the Medium and Low nutritional plans. Most of the performance, carcass, and meat quality traits that were evaluated in barrows and gilts were not affected by the nutritional plans. In general, Duroc and Pietrain crossbred pigs had a greater performance and carcass yield when compared to Piau crossbred pigs.

O aumento do número de leitões nascidos vivos de fêmeas hiperprolíficas aumenta a variabilidade do peso ao nascer e faz muitos produtores praticarem a equalização de leitegadas, que consiste na uniformização do peso e número de leitões de acordo com a capacidade da matriz. Com o objetivo de avaliar o efeito da equalização de leitegadas sobre o crescimento e mortalidade de leitões, estudaram-se dados históricos de duas unidades produtoras de leitões da região centro-oeste de Santa Catarina. Foram pesados 1440 leitões ao nascer, desmame e saída de creche, nascidos de 130 matrizes comerciais Agroceres PIC®. Os pesos ajustados aos 21 e 58 dias de idade e os respectivos ganhos médios diários foram submetidos à análise de regressão múltipla por meio do procedimento GLM do programa estatístico SAS (2005), e a ocorrência de mortalidade foi estudada pelo procedimento GENMOD do mesmo programa. Foram considerados como efeitos fixos a transferência e grupo de contemporâneos e como covariáveis o peso ao nascer ou desmame, número de leitões após equalização e número de leitões desmamados, além dos efeitos linear e quadrático da ordem de parto da matriz; no estudo da ocorrência de mortalidade o peso ao nascer foi considerado como covariável. Os leitões adotivos pesaram 207 gramas a menos que leitões biológicos no período da maternidade (P<0,01) e maior sobrevivência entre os leitões leves. No entanto, o efeito da equalização não promoveu diferenças no período de creche entre os leitões adotivos e aqueles criados por suas mães biológicas.

The high number of piglets born alive from hiperprolifics sows increases the variability of weight at birth and made many producers practice cross-fostering management, which consists in standardization of weight and number of piglets according to the sow ability. To evaluate the effect of cross-fostering on performance and mortality occurrence of piglets, historical data were studied from two producers of the Midwest region of Santa Catarina-Brazil. Were weighed 1440 piglets at birth, weaning and 37 days post weaning from 130 commercial sows of Agroceres PIC®. The adjusted weights at 21 and 58 days old and their respective gain were submitted to multiple regression analysis using the GLM procedure of SAS Statistical Software (2005), and occurrence of mortality was studied by GENMOD procedure. For performance traits were considered fixed effects the cross-fostering, contemporary group and covariables the birth weight or weaning, the number of piglets after equalization, number of weaned piglets, linear and quadratic effects of sow parity; the weight at birth were included as covariable for occurrence of mortality. Cross-fostered piglets weighed 207 grams less than biological piglets (P<0.01) and had lesser mortality between lightest piglets. However, the littermate equalization did not promote differences in growth period between cross-fostered and biological piglets.