Abstract A total of 378 barrows and gilts (PIC 337 × Camborough; initial BW = 6.57 ± 0.88 kg) were used in a 42-d growth trial conducted at the Agroceres Multimix Research Center (Minas Gerais, Brazil) to evaluate the effects of different lactose feeding programs on nursery pig performance and diarrhea incidence. Pigs were weaned at approximately 21 d of age and assigned to one of three dietary treatments that provided lactose for varying durations through 28 d post-weaning. There were 54 mixed-sex pens (7 pigs per pen; 18 pens per treatment) arranged in a randomized complete block design, blocking by weaning weight. The treatments were: Trt1, 15% lactose from d 0 to 7, 10% from d 7 to 14, and 5% from d 14 to 28; Trt2, 15% lactose from d 0 to 7, 10% from d 7 to 14, and 5% from d 14 to 21; and Trt3, 15% lactose from d 0 to 7 and 10% from d 7 to 14 post-weaning. Lactose levels were achieved by adjusting the proportions of dried whey, whey permeate, and corn. Diarrhea incidence was assessed by daily individual observation of the animals, always in the morning and throughout the overall period. Growth performance data were analyzed using generalized linear mixed models (lmer function, R), and diarrhea incidence was analyzed using a binomial distribution (glmer function). Pigs fed diets containing lactose up to 21 d postweaning had greater BW at d 21 (P = 0.005), higher ADG (P 0.001), ADFI (P 0.001) and higher or equal G:F (P = 0.019) from d 14 to 21 compared with pigs fed no lactose after d 14. From d 21 to 28, lactose inclusion increased ADFI (P = 0.046) and worsened G:F (P = 0.002). Across the entire experimental period (d 0–28), pigs fed lactose for at least three weeks had higher ADFI (P = 0.010), whereas G:F was equal or lower compared with Trt3 (P = 0.043), where pigs were fed lactose-free diets from d 14 to 21. Diarrhea incidence was significantly reduced in pigs receiving lactose during d 14 to 21 and d 21 to 28 (P 0.001), accompanied by decreased injectable medication use (P 0.001). In conclusion, although no differences were observed in overall performance from d 0 to 42, early lactose withdrawal increased diarrhea incidence and the need for medical interventions in nursery pigs.
Kunrath et al. (Wed,) studied this question.