Effects of thermal processing (toasting or extrusion) of untoasted soybean meal on growth performance, apparent ileal nutrient digestibilities, and chyme characteristics were studied in broiler chicks fed diets with soybean meal as the main protein source. Effects of increasing shear forces during extrusion as well as enzyme treatments (protease and carbohydrase) were also studied. When compared with toasting, extrusion significantly improved feed conversion ratio (1.56 vs 1.62) and apparent ileal digestibilities of CP and nonstarch polysaccharides (87.5 vs 82.2% and 26.7 vs 11.4%, respectively). Enzyme treatment improved apparent ileal digestibility of CP and nonstarch polysaccharide compared with no enzyme treatment (85.2 vs 83.7% and 20.6 vs 14.5%, respectively); however, enzyme treatments did not result in a better growth performance of the chicks. Among the enzyme treatments, no differences were found in growth performance and apparent ileal CP digestibility, whereas the carbohydrase significantly improved apparent ileal nonstarch polysaccharide digestibility compared with the other enzyme treatments. Extrusion of SBM at the highest shear level caused a significant increase in the water-holding capacity, chyme viscosity, and concentration of soluble nonstarch polysaccharides in the chyme compared with extrusion of SBM at lower shear levels. The increase in chyme viscosity did not affect growth performance, nor did it influence apparent ileal nutrient digestibilities.

Meat and bone meal is a valuable protein and mineral source in diets of production animals and contributes to the protein, energy and mineral component of diets. The aim of the present study was to more accurately characterise the apparent ileal amino acid digestibility of meat and bone meals produced in New Zealand and evaluate routine in vitro assays used in practise to measure meat and bone meal quality. A total of 94 commercial meat and bone meals from 25 New Zealand rendering plants over a two and a half year period were analysed for proximates, gross energy, gross amino acid content (incl. hydroxyproline, hydroxylysine and lanthionine), apparent ileal amino acid digestibility, pepsin nitrogen digestibility, protein solubility and bone content. The mean crude protein content of the 94 meat and bone meal samples was 56.8% with a range of >35% units and a coefficient of variation of 9.8%. The mean crude fat and ash content were 10.0 and 28.4% respectively. These latter components showed a large range (16 and 43%, respectively) with coefficients of variation above 22%. Amino acid digestibility between samples was highly variable with lysine and sulphur amino acids digestibility ranging between 45.8-89.0 and 38.2-85.5%, respectively. Pearson correlation coefficients are presented between crude protein content and individual gross amino acids, crude protein content and individual digestible amino acid content, and pepsin N digestibility and individual digestible amino acid content. There was a significant relationship between the digestible amino acid nitrogen content and the crude protein content while pepsin nitrogen digestibility was not correlated to ileal amino acid nitrogen digestibility (r=-0.06). Meat meals with a high protein content had relatively low hydroxyproline and hydroxylysine levels something that was attributed to the levels of collagen from bone. The data indicated that lanthionine (formed upon heat treatment of cysteine with a hydroprotein) is not a good indicator of the heat treatment employed to meat and bone meals.Step-wise multiple regression equations to predict the apparent digestible content of amino acids from rapid in vitro assays are presented. The most selected variables included ash and crude fat content. In general the equations derived for the essential amino acids had a higher degrees of fit (R 2 ) compared to the non-essential amino acids. The R 2 for the essential amino acids ranged from 0.43 for histidine and 0.68 for leucine. These equations provide a means of more rapidly estimating the apparent ileal digestible amino acid content (protein quality) of meat and bone meal using standard analyses.

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Genetic selection for increased litter size of sows increases the risk of a large negative energy balance during lactation. Furthermore, the feed intake capacity of the lactating sows might be reduced due to the simultaneous selection for greater feed efficiency during the growth phase when sows were actually reared as finishers but later on selected for breeding. There is a need to improve lactation performance of sows and continue selection for feed efficiency of grower-finishers in commercial breeding. Therefore, this study was conducted to estimate genetic correlations between growing-finishing traits and lactation performance traits. An additional objective was to study the impact of including additive social effects in the animal model on genetic correlation estimates. Analyses were performed on a population of 1,149 commercial crossbred sows with repeated observations on lactation performance traits and their 7,723 grower-finisher offspring. The genetic correlation between daily BW gain of grower-finishers and starting BW of lactating sows was positive (rg = 0.24; P < 0.05). The correlation between off-test backfat of grower-finishers and fat mass of lactating sows was also positive (rg = 0.53; P < 0.05). The genetic regulation of feed intake from the beginning of lactation seems to differ from the genetic regulation of feed intake during the growing-finishing period, as the correlation between these 2 traits was low (rg = +0.23; P < 0.05). Feed efficiency during growing-finishing and lactation phases showed similar tendencies as the genetic correlation between residual feed intake of the grower-finisher and lactation efficiency of sows was -0.51 (P < 0.05). Taking heritable social effects into account for daily BW gain and feed intake did not affect the genetic correlation estimates, either within growing-finishing traits or between growing-finishing traits and lactation performance traits. It was concluded that in the absence of antagonistic genetic correlations, selection for growing-finishing traits in dam lines could be combined with selection for lactation performance traits.

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