Effect of Protein Level during Gestation and Lactation on Reproductive Performance in Swine

Four hundred and three litters were used at six stations to evaluate the effects of protein levels during gestation and lactation on litter size and pig weight at birth and 14 days of age. Dietary treatments, based on corn and soybean meal, included two gestation protein levels, 9 and 15%, and three lactation protein levels, 12, 16 and 20%. Several stations participated in the lactation phase, whereas one station fed the gestation protein levels and the 12 and 16% lactation protein diets. Daily feed intake was restricted to 2.0 kg per head daily during gestation. Feed was allowed ad libitum during lactation or was fed at a daily rate of 3.6 kg to first-litter gilts, 4.3 kg for second-litter sows and 5.0 kg for sows having three or more litters. Analysis of the data from four stations using all six diet treatments showed that the diet response within a station was similar and that there were no station by diet interactions. Sows fed 9% protein during gestation tended to farrow fewer pigs per litter; however, gestation protein level had little effect on average pig birth weight or number and weight of pigs at 14 days of age. Birth weight of live pigs farrowed decreased (P<.05) and 14-day weight increased (P<.05) with increasing lactation protein level, particularly between the 12 and 16% protein level. The gestation by lactation protein level interaction was statistically significant for birth weight of live pigs farrowed. With the 9% gestation protein level, pig birth weight decreased with increasing lactation protein level; whereas, with the 15% gestation protein level pig birth weight was similar among lactation protein levels. Although not statistically significant pig weight and gain at 14 days of age was improved more with an increase in lactation protein level from 12 to 16% in sows fed a 9% gestation level than with increasing lactation protein levels in sows fed a 15% gestation protein level. Results of the study show that the N.R.C. recommended lactation protein level (15%) is sufficient for optimal reproduction performance.