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Intrauterine growth restriction (IUGR) is a serious condition which impairs the achievement of the fetus' full growth potential and occurs in a natural and severe manner in pigs as a result of placental insufficiency. Reduced skeletal muscle mass in the fetus with IUGR persists into adulthood and may contribute to increased metabolic disease risk. To investigate skeletal muscle postnatal development, histomorphometrical patterns of the semitendinosus muscle, myosin heavy chain (MyHC; embryonic I, IIA, IIB and IIX isoforms) fiber composition and the relative expression of genes related to myogenesis, adipogenesis and growth during three specific periods: postnatal myogenesis (newborn to 100 days old), hypertrophy (100-150 days old), and postnatal development (newborn to 150 days old) were evaluated in female pigs with IUGR and normal birth weight (NW) female littermates. NW females presented higher body weights compared to their IUGR counterparts at all ages evaluated (P < 0.05). Moreover, growth restriction in utero affected the semitendinosus muscle weight, muscle fiber diameter, and muscle cross-sectional area, which were smaller in IUGR pigs at birth (P < 0.05). Notwithstanding the effects on muscle morphology, IUGR also affected muscle fiber composition, as the percentage of MyHC-I myofibers was higher at birth (P < 0.05), and, in 150-day-old gilts, a lower percentage of MyHC-IIX isoform (P < 0.05) and the presence of embryonic MyHC isoform were also observed. Regarding the pattern of gene expression in both the postnatal myogenesis and postnatal development periods, IUGR led to the downregulation of myogenic factors, which delayed skeletal muscle myogenesis (PAX7, MYOD, MYOG, MYF5 and DES). Altogether, growth restriction in utero affects muscle fiber number and size at birth and muscle fiber composition through the downregulation of myogenic factors, which determines the individual´s postnatal growth rate. This fact, associated with delayed myofiber development in growth-restricted animals, may affect meat quality | 841 FELICIONI Et aL. | Muscle fiber diameterThe diameter of the muscle fibers cross-section [Feret's diameter (Dubache-Powell, 2008)] was determined using digital images randomly selected in the newborn, 100-day-old and 150-day-old pigs

The aim of the study was to evaluate the influence of different temperature control systems on the voluntary feed intake (VFI), percentage of weight loss (PWL) and performance of lactating sows as well as on the weight of their piglets. Two systems were used: traditional temperature control system (TTCS) with curtain management and an evaporative snout cooling system (ESCS RESUMO O objetivo do estudo foi avaliar a influência de diferentes sistemas de controle de temperatura sobre o consumo voluntário de ração (VFI), porcentagem de peso perdido (PWL) e desempenho de fêmeas lactantes e de suas leitegadas. Dois sistemas foram utilizados no estudo: o sistema tradicional de controle de temperatura (TTCS), com manejo de cortina e o sistema de resfriamento adiabático evaporativo (ESCS). O estudo foi realizado no verão de 2011. Após o parto e ao desmame, 241 fêmeas foram pesadas e foi avaliado o PWL durante a lactação. Fêmeas TTCS perderam mais peso (5,3±0,9%; P<0,05) do que as fêmeas ESCS (2,2±0,9%). VFI foi medido em intervalos de quatro dias em 32 fêmeas primíparas e 39 multíparas. Fêmeas ESCS tiveram maior VFI (5,8±0,2kg -1 dia; P<0,05) do que fêmeas TTCS (4,8±0,2 kg dia -1 ). Primíparas (4,4±0,2kg dia -1 ) tiveram menor VFI

No abstract

Lysine requirements for gain in maternal body reserves and piglet birth weight, during pregnancy, in contemporary prolific genotypes, are not well established. This study aimed to evaluate the effect of dietary lysine in late pregnancy on piglet birth weight, and on the gestational and lactational performance of gilts. Pregnant gilts were uniformly distributed into two groups and received, from 85 to 110 days of gestation, either of two lysine levels in their diet: Control group - 28g lysine/day (n=136), and Lysine group - 35g lysine/day (n=141). There were no effects (P>0.10) of supplemental lysine on body weight and backfat (BF) gain of females or on piglet birth weight. Gilts supplemented with lysine tended to have a lower percentage of stillbirths (P=0.077), reduced within-litter birth weight variation (P=0.094) and a lower percentage of piglets weighing less than 1100g (P=0.082) than in the Control group. During lactation, the performance of sows and litters was also evaluated in a subgroup of sows (n=26/group). There were no differences between the Control and Lysine groups (P>0.10) in voluntary feed intake, body reserve losses (weight and BF), weaning-to-estrus interval of the sows, and litter weaning weight. In conclusion, an increase in lysine (from 28 to 35g/day) in late gestation of gilts (85 to 110 days) tends to reduce the rate of stillbirths and to improve the uniformity of litter weight at birth, but does not affect the performance of females until farrowing or during subsequent lactation.