M.E. Einstein

Evaluation of the growth of backfat depth, loin depth, and carcass weight for different sire and dam lines.

The growth of 1,990 barrows and gilts of 3 sire and 2 dam lines was evaluated over 2 replicates. Pigs were weighed and ultrasonic backfat and loin depth measurements were taken at approximate 28-d intervals from 37kg BW to target BW of 113, 127, or 141kg. Carcass backfat and loin depths were measured with an optical probe. An exponential equation Y = exp(b0 + b1X + b2X2) + ai[exp(b0 + b1BW + b2BW2)]D (where Y is the value of the measurement; b0, b1, and b2 are regression coefficients; and D is a parameter) with a pig-specific random effect (ai) provided the best fit of the ultrasonic data to BW. The ultrasonic backfat depths were affected (P < 0.01) by replicate, dam line, and the interactions of replicate × BW and dam line × BW. The ultrasonic backfat depths of the gilts increased at a rate of 0.0077cm/kg BW gain at 40 kg BW to 0.0115 cm/kg BW gain at 135kg BW. Barrows had backfat growth rates of 0.0110 cm/kg BW gain at 40 kg BW, which increased to 0.0149 cm/kg BW gain at 115 to 125 kg BW. The ultrasonic loin depths were affected (P < 0.05) by replicate, sire line, and replicate × BW and sire line × BW interactions. Carcass backfat and loin depths were affected (P < 0.01) by replicate, sire line, dam line, target BW, sex, and the sire line × sex interaction. Pigs of different sire and dam lines have different rates of backfat and muscle growth, indicating differences in compositional growth.

Evaluation of Different Mixed Model Nonlinear Functions to Describe the Feed Intakes of Pigs of Different Sire and Dam Lines1

Daily individual feed intakes (DFI) of 1,932 barrows and gilts from 3 sire and 2 dam lines were evaluated over 2 replicates. Five functions relating DFI to age or BW were evaluated: linear-quadratic, exponential, generalized Michaelis-Menten, nonlinear, and Bridges functions. The Bridges function provided the best fit to DFI data. Two pig-specific random effects were included. The barrow and gilt data were fitted separately because their values for one parameter of the Bridge function were different. For DFI, there were overall significant effects (P < 0.05) for replicate, sex, and the sire line × dam line interaction. Repeated measures analyses indicated significant (P < 0.001) interactions of sire line, sex, and replicate, with age and BW indicating that the shapes of the DFI curves were different for the pigs of the different sire lines, sexes, and replicates. The research indicates that separate DFI curves are needed for each sire line and sex, and potentially for season. Daily feed:gain values were estimated for each pig by using a generalized Michaelis-Menten function previously fitted to the BW data. The analyses of feed:gain values indicated significant (P < 0.05) effects for sire line, dam line, sex, sire line × sex, and sire line × replicate.

Impact of Weaning Weight and Early Postweaning Growth of Pigs to Late Finishing Growth When Fed Either Corn- and Soybean Meal-Based Diets or Low Nutrient Excretion Nutrient-Dense Diets

ABSTRACT The BW growth of 1,385 barrows and gilts was evaluated from d-21 weaning to 130 kg BW. The pigs were assigned to a 2×2 factorial arrangement of treatments. The pigs were fed a series of either standard corn- and soybean meal-based control diets or low nutrient excretion nutrient-dense (LNE-ND) diets from 1 wk postweaning to 130 kg BW and assigned to rooms with either deep pit or pull plug-recharge manure storage treatments. The pigs were weighed at weaning, at 7 and 14 d postweaning, and at approximately 2-wk intervals from 28 d postweaning to a mean BW of 130 kg. Mixed model nonlinear equations including pig-specific random effects were evaluated for the generalized Michaelis-Menten function. The serial postweaning BW data were fitted to a mixed model generalized Michaelis-Menten equation. Relationships of weaning BW to late finishing BW and days to 125 kg BW were different for each dietary treatment. Late finishing BW and days to 125 kg BW had nonlinear relationships with weaning BW for pigs fed the LNE-ND diets and had linear relationships for pigs fed the control diets. The predicted changes in subsequent BW of the LNE-ND diets per kilogram of change in weaning BW were greater for pigs with the lightest weaning BW than for pigs with average to above-average weaning BW. Across both dietary treatments, pigs with greater weaning BW and greater early postweaning ADG required fewer days to achieve target market BW.

Evaluation of Alternative Methods to Develop Prediction Equations to Predict Carcass Fat-Free Lean Mass1

Abstract Carcass measurements of 203 pigs representing 7 genetic populations and 4 target weights (100, 114, 128, and 152 kg) were used to evaluate alternative equations to predict carcass fat tissue-free lean mass. Independent variables in the equations included carcass weight and measures of backfat depth and longissimus area. Alternative sets of equations were calculated to evaluate the inclusion of a random effect of week of processing and of the quadratic and cross-product independent variables. In addition, equations were developed from data including the overall data set as well as from the 3 lightest and 3 heaviest target weights. Overall, the addition of the random effect of week did not change the residual standard deviations of the prediction equations. For 4 equations, the inclusion of the random effect of week reduced the absolute value of the regression coefficients. The best equations developed from either the light or heavy pig data sets had less total residual sums of squares and less residual sums of squares accounted for by target BW group than did the best equations developed from the overall data set. In 2 of the 4 cases, the best linear equation developed from the light or heavy data sets had less residual sums of squares than the best equation based on the overall data set.