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Identifying characteristics of slow-growing pigs from birth to 9 weeks of age and growth performance responses to feeder space post-weaning
Slow-growing (SG) pigs can be characterized as those that have less BW per day of age than their contemporaries, and negatively affect profitability and animal well-being in pork production systems. Limited feeder space allowance may further suppress growth of SG pigs after weaning. The objectives of this study were to identify characteristics and investigate the effect of feeder space allowance on growth performance of SG pigs during the nursery period. Pigs (n = 592) were weighed individually at birth and weaning at 4 wks of age, and categorized as slow (the lightest 30%), fast (the heaviest 30%), and normal (the middle 40%) growth based on BW/d of age at nursery exit (9 wks of age). Pigs were randomly allotted to pens (8 pigs/pen; 0.3 m2/pig) with 1 of 2 feeder-space treatments: 1) 5 feeder spaces/pen (5SP) or 2) 2 feeder spaces/pen (2SP) by covering 3 of the 5 spaces. Pigs were weighed individually at 1, 3 and 5 wks after weaning. Focal pigs (n = 96) consisting of 48 slow and 48 fast growing pigs were used to determine rate of feed consumption at 55 d of age. Data were analyzed using the Mixed Procedure of SAS with repeated measures. Slow-growing pigs provided 5SP had greater ADG during wks 1 to 3 (0.285 vs. 0.248 ± 0.011 kg/d, respectively; P < 0.01), wks 3 to 5 (0.553 vs. 0.537 ± 0.005 kg/d, respectively; P = 0.02), and the overall 5 wk nursery period (0.303 vs. 0.293 ± 0.002 kg/d, respectively; P < 0.01) than those provided 2SP. Compared with fast-growing pigs, SG pigs had lighter birth weight (1.4 vs. 1.7 ± 0.02 kg, respectively; P < 0.01), lower ADG (0.441 vs. 0.659 ± 0.003 kg/d, respectively; P < 0.01) during the nursery period, and slower growth rate (0.298 vs. 0.450 ± 0.002 kg/d; P < 0.01) by nursery exit. Slow-growing pigs ate slower (14.2 vs. 20.4 ± 0.85 g/min; P < 0.01) than fast-growing pigs. These results suggest that SG pigs have low birth weight, lower feed consumption rates, and consequently, have reduced growth rates during the nursery period. Providing more feeder space improved growth rate of SG pigs during the nursery period.
Keywords: feed consumption rate, feeder space, slow-growing pigs