Effect of dietary energy level and weaning weight on growth performance and digestibility in weanling piglets

Abstract Text: The experiment was conducted to determine the capacity of piglets weaned at light weight to achieve similar growth performance with those weaned at heavy weight by increasing the ME content of the diet and keeping constant Lys:ME. Thirty two male piglets were classified according to their weaning weight (WW) as light (4.5 ± 0.4 kg) or heavy (6.7 ± 0.5 kg) and housed individually in metabolic cages for 28 d. Six treatments, 2 WW and 3 ME levels (I: 3,400; II: 3,600; and III: 3,800 kcal/kg) in a 2 x 3 factorial arrangement, were used in pre-starter (PS, d 0 to 14) and starter (ST, d 14 to 28) period. The control diet (I) was formulated with standard energy and nutrient recommendations (Brazilian Tables for Poultry and Swine), whereas indispensable and dispensable AA, Ca, P, and lactose levels in the diets II and III were adjusted for the increased ME (e.g.,4.14 and 3.91 g Lys/Mcal ME for the PS and ST periods, respectively). Fecal and urine samples were collected to determine apparent total tract digestibility (ATTD) of energy and nutrients. Age at weaning was used as covariate in the statistical model. There were no WW x ME interactions for any of the response criteria. Overall, light WW piglets had less ADG and AFDI (P < 0.05), but there was no difference in the G:F. Heavy WW piglets ingested more ME, Lys, and N than light WW piglets during the entire phase (P < 0.05). During the PS period there was a linear effect of ME on G:F; increasing ME improved G:F (P < 0.05). Also in this period, the increment in ME increased ATTD of GE, and DE and ME values (P < 0.05). During the ST and total period, there was no effect of increased ME levels on  ME and Lys intake, but increasing ME levels increased ATTD of GE, CP, and DM, N retention, and DE and ME values (P < 0.05). In conclusion, light piglets did not improve growth performance when fed diets with increasing ME levels. Increased ME levels improved digestibility and utilization of nutrients, but did not improve growth performance. 

Keywords: energy density, nursery piglets, weaning weight