Date Full Report Received08/13/2014
Date Abstract Report Received08/13/2014
InvestigationInstitution: ARS, MARC, USDA
Primary Investigator: Jeffrey Vallet
Co-Investigators: Dan Nonneman, Gary Rohrer, Kenneth J. Stalder, Lea Rempel, Gary Bradley, Julia Calderon, Brad Freking, Clay Lents, Jeremy Miles, Christina Phillips
Funded ByNational Pork Board
Sow longevity is a key component for efficient and profitable pig farming and efforts to improve it should start with the adequate management of replacement gilts. A key factor in gilt management is to provide them with adequate feeding that supplies the right amount of amino acids and energy for their maintenance and growth to allow them to reach puberty at an early age and build up fat reserves to be later used during their first lactation. Therefore, six different diets, consisting of 2 levels (85% and 100% ) of lysine (LYS) and 3 levels (85%, 100% and 115% ) of metabolizable energy (ME) were used in this study to try to manipulate the lean to fat ratio in replacement gilts by creating a lysine and/or energy imbalance in the diet. The 100% LYS, 100% ME were based on an informal survey of the swine industry to obtain average levels that are currently fed to gilts. Gilts had free access to diets from 100 days of age until approximately 260 days of age, when they were slaughtered. Data on litter of origin of the gilts, growth, body composition, feed intake, feed efficiency, age at puberty, measurements of the reproductive tract at the time of slaughter and carcass composition were collected for this study. We found no difference in growth and minor differences in body composition traits among the six diets. However, gilts fed a low energy diet consumed almost 15 kg more feed than gilts fed a high energy diet, indicating that gilts adjusted their feed intake according to the energy in the diet. Thus, regardless of the diet, gilts used the same amount of Mcal to deposit 1 kg of body weight. Also, LYS consumption was higher (on average 26 g/day) than the recommended lysine intake irrespective of the diets. Therefore, despite considerable differences in the ratios of ME and LYS in the diets, they had very little effect on measures of growth or body composition. We also did not observe a difference in the age at puberty or in the measurements taken of the reproductive tract between diets. Ovulation rate, uterus length and ovary length and width were a function of age, stage of the estrous cycle and the number estrous cycles rather than feed provided or body condition. Carcasses from gilts fed a high energy diet, were almost 3 kg heavier than carcasses from gilts fed a low energy diet, most likely due to a larger organ size and heavier organ weight of the gilts fed the low energy diets. More research is necessary in order to find an ‘ideal’ gilt development diet that would create an amino acid and/or energy imbalance and decrease lean deposition and increase fat reserves in replacement gilts with free access to feed.