Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science


A growth trial and a nitrogen and energy balance trial were conducted simultaneously to determine the effects of two lysine:metabolizable energy ratios (L YS/ME) on growth performance and protein deposition in boars, barrows, and gilts from 59 to 86 kg. Twenty-four pigs (two boars, two barrows, and two gilts from each of four litters, with average initial weights of 59.06, 57.53, and 58.82 kg, respectively) were used in the growth trial in a randomized complete block design with treatments (diet and sex) in a 2 x 3 factorial arrangement in the growth trial. In addition, one boar, one barrow, and one gilt from each of two litters were slaughtered at 59 kg to determine initial body composition. Two diets were formulated for each sex, LO containing 2.9, 2.0, and 2.5 and HI containing 3.4, 2.5, and 2.0 g L YS/ME for boars, barrows, and gilts, respectively. Pigs were individually penned with ad libitum access to feed and water. At slaughter, blood, head/feet/empty viscera (inedible fraction), and carcass were taken from each pig as well as carcass measurements. After freezing, the right half of the carcass and the inedible fractions were ground to obtain homogenous samples for separate proximate analyses. Gilts had lower daily gain than boars which had lower daily gain than barrows (Ps.01). Gilts and boars had similar daily feed intakes and both consumed less than barrows (Ps.05). A diet by sex interaction occurred for gain:feed ratio (G/F). Barrows fed LO had higher (Ps.01) G/F than when fed HI, whereas G/F was not affected by diet for boars or gilts. Interactions between diet and litter and litter and sex also occurred for G/F. Dressing percent (DP), hot carcass weight (HCW), and longissimus muscle area (LMA) were not different (P> .10) among the sexes. Lean percentage and lean growth per day was similar between gilts and boars (P>.10) and both were higher than barrows (Ps .05). There were no differences (P>.10) due to L YS/ME for ADG, ADFI and carcass characteristics. Dietary L YS/ME had no effect on carcass and whole body H2O, CP, fat, and ash deposition rates or composition with the exception that ash content of the whole body was higher for pigs fed the HI diet compared to the LO diet (P s: .10). All carcass and whole body composition criteria and deposition rates were different (P s: .10) among the sexes with the exception of the ash deposition. Plasma urea N was higher for pigs fed the HI L YS/ME compared to the LO L YS/ME (Ps.01) and was not different among the sexes (P>.10). Various interactions occurred between litter and sex and diet and sex for fat deposition and calculated energy retention (Ere). Adjustment of the NPPC (1991) lean gain equation for 5% fat and 1.06% ash and dividing by the H2O: protein ratio in gain gave a calculated CP deposition value that was directly compared to the actual CP deposition. This method very closely predicted CP deposition in barrows and gilts and greatly underestimated (20 g/day) CP deposition in boars. In the nitrogen and energy balance trial, one boar, one barrow, and one gilt from each of two litters were used in a cross-over design with the same L YS/ME in the growth trial. Pigs were housed in individual metabolism crates and fed twice daily throughout a 5-day adaptation period and 5-day collection period. Digestibility and metabolizability of gross energy were not different (P> .10) among the sexes or between diets. Daily N retention and N retained per kg BW·75 were not different (P>.10) between boars and barrows but were lower (P ~ .10) for gilts, although N retention per Meal ME intake was not lowest (P ~ .10) for gilts but intermediary between boars and barrows. A period by diet interaction occurred for daily N retention, CP deposition, N retention per kg BW·75, N retained per Meal ME intake, and N retained per N intake.

Library of Congress Subject Headings

Swine -- Growth

Swine -- Feeding and feeds

Lysine in animal nutrition



Number of Pages



South Dakota State University