The objective of this study was to investigate the relationships among birth weight, birth order, or litter size on growth performance, carcass quality, and eating quality of the ultimate pork product. Data were collected from 98 pig litters and, with the addition of recording birth weight and birth order, farrowing and piglet management were according to normal barn practices. In the nursery and during growout, the pigs received the normal feeding program for the barn and, with the addition of individual tattooing, were marketed as per standard procedure. From 24 litters, selected because they had at least 12 pigs born alive and represented a range of birth weights, 4 piglets were chosen (for a total of 96 piglets) and sent to Agriculture and Agri-Food Canada-Lacombe Research Centre (Lacombe, Alberta, Canada) when they reached 120 kg for extensive meat quality and sensory analysis. Individual BW was measured at birth, on the day of weaning, 5 wk after weaning, at nursery exit, at first pull, and at the time of marketing. Litter sizes were divided into 3 categories: small (3 to 10 piglets), medium (11 to 13 piglets), and large (14 to 19 piglets). There were 4 birth-weight quartiles: 0.80 to 1.20, 1.25 to 1.45, 1.50 to 1.70, and 1.75 to 2.50 kg. Increased litter size resulted in reduced mean birth weight (P < 0.05), but had no effect on within litter variability or carcass quality (P > 0.05) when slaughtered at the same endpoint. Lighter birth-weight pigs had reduced BW at weaning, 5 and 7 wk postweaning, and at first pull and had increased days to market (P < 0.05). Birth weight had limited effects on carcass quality, weight of primal cuts, objective quality, and overall palatability of the meat at the same slaughter weight (P > 0.05). In conclusion, increased litter size resulted in decreased mean birth weight but no change in days to market. Lighter birth-weight pigs took longer to reach market. Despite some differences in histological properties, birth weight had limited effects on carcass composition or final eating quality of the pork when slaughtered at the same BW and large litter size resulted in more pigs weaned and marketed compared with the smaller litters. We concluded that based on the conditions of this study, other than increased days to market, there is no reason based on pig performance or pork quality to slow down the goal of the pork industry to increase sow productivity as a means to increase efficiency.

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. 2001. Effects of feeding different levels of conjugated linoleic acid and total oil to pigs on live animal performance and carcass composition. Can. J. Anim. Sci. 81: 505-510. The effects of feeding different dietary levels of conjugated linoleic acid (CLA) and total oil (TO) were evaluated using 216 barrows fed from 36 to 115 kg body weight. A 3 × 2 factorial design was used with three levels of dietary CLA (0, 0.25, and 0.5%), two levels of dietary TO (2 and 5% made up with canola oil) and 12 pens of three barrows fed per diet. Pigs on all diets gained weight at the same rate from 0 to 4 wk (36 to 61 kg) and from 4 wk to slaughter (61 kg to 115 kg) (P > 0.05). Pigs fed 5% versus 2% TO had 6.6% lower feed intake from 0 to 4 wk (P = 0.02) and 5.9% lower feed intake from 4 wk to slaughter (P < 0.003), while feeding CLA had no effect on feed intake (P = 0.70). A CLA by TO interaction for feed intake was not found for 0 to 4 wk but from 4 wk to slaughter a tendency for an interaction (P = 0.06) was found indicating 0.25% CLA may depress feed intake at 2% TO while stimulating intake at 5% TO. Increasing TO and CLA increased the lean content in commercial cuts by 1.6% (P = 0.06) and 2.7% (P = 0.008), respectively. A CLA by TO interaction (P = 0.012), however, indicated CLA was less effective at increasing lean when added to 5% TO diets than to 2% TO diets, with pigs fed the 0% CLA/2% TO diet yielding 5% less lean than pigs fed any of the other diets (P < 0.05). Interestingly, a main effect for TO was not found for subcutaneous fat (SCF), but adding CLA reduced SCF (6.6%; P = 0.002). Again, a CLA by TO interaction (P = 0.008) indicated adding CLA was less effective at reducing SCF in 5% TO than 2% TO diets, with pigs fed the 0% CLA/2% TO diet having 9.7% more SCF than pigs fed any of the other diets (P < 0.05). The difference in effectiveness of CLA at different TO levels might be due to dilution of CLA by canola oil fatty acids and/or canola oil having fat to lean repartitioning effects of its own. A comparison of fats and oils with differing chain lengths and degrees of saturation would, therefore, be of interest to further define their potential differential effects on growth and metabolism. . La prise alimentaire des truies qui recevaient 5 % de HT plutôt que 2 % a diminué de 6,6 % lors des quatre premières semaines (P = 0,02) et de 5,9 % de 4 semaines à l'abattage (P < 0,003), alors que l'ingestion d'ALC n'a eu aucun effet sur ce paramètre (P = 0,70). L'ALC n'interagit pas avec la HT au niveau de la prise alimentaire de 0 à 4 semaines, mais de 4 semaines à l'abattage, on note une tendance en ce sens (P = 0,06) indiquant qu'à partir de 0,25 %, l'ALC pourrait réduire la prise alimentaire dans les rations contenant 2 % de HT et l'augmenter quand la ration en renferme 5 %. Quand on augmente la proportion d'ALC et de HT, la teneur en viande maigre des morceaux commerciaux augmente de 1,6 % (P = 0,06) et de 2,7 % (P = 0,008), respectivement. Une interaction entre l'ALC et la HT (P = 0,012) révèle néanmoins que l'ALC ...

1991). Growth characteristics and carcass composition of pigs with known genotypes for stress susceptibility over a weight range of 70 to 120 ABSTRACT A total of 805 Lacombe pigs of different genotype with respect to halothane sensitivity (halothane positive, nn = 205; heterozygote, Nn = 214; halothane negative, NN = 386) were slaughtered over a range in live weight (70 to 120 kg) to assess tissue growth patterns using the allometric equation (y = aX h ). The nn genotype was older at slaughter than the NN genotype, but pigs from each genotype were killed over a similar weight range. The relative growth of the primal cuts was influenced by genotype, with nn pigs having a lower coefficient for the bottom shoulder (picnic) and a higher coefficient for the belly. The relative growth of bone was similar for genotypes (P > 0-05) but the relative growth of lean was lower and the relative growth of total fat and depot fat (subcutaneous and intermuscular) was higher for the nn genotype compared with the Nn and NN genotypes. On a within-tissue basis, the relative growth of the tissues in each primal was similar, except for the ham, where the relative growth of lean was higher for nn pigs compared with the two other genotypes. Small differences in tissue distribution were evident, but seldom exceeded 30 g/kg. Although nn pigs had a higher lean content and higher lean: bone ratio than Nn or NN pigs at similar live weights, their relative advantage in composition decreased with increasing live weight.

, I. L. 2004. Practical dietary levels of canola oil and tallow have differing effects on gilt and barrow performance and carcass composition. Can. J. Anim. Sci. 84: 661-671. Previously we demonstrated that barrows produced leaner carcasses when fed 5% versus 2% canola oil. The present trial was conducted to determine if the same would be true for gilts or when feeding beef tallow (a source of saturated fatty acids). Four diets were fed (2 or 5% canola oil or digestible energy equivalents of tallow), and 27 gilts and 27 barrows were fed each diet. Experimental diets were fed from 49.4 to 113.5 kg body weight. Barrows fed 2% canola oil had similar average daily gains (ADG) relative to gilts (P > 0.05) fed any diet, but grew slower than barrows fed 5% canola oil (0.99 vs. 1.08 kg d -1 ; P < 0.05) and tended to have lower ADG relative to barrows fed diets containing tallow (P < 0.10). Barrows fed 2% canola oil had poorer feed conversion efficiency (kg feed kg -1 gain) relative to animals fed any other diet (P < 0.05). For barrows, feeding the 2% canola oil resulted in more subcutaneous fat relative to feeding 2.16% tallow (+18 g kg -1 lean cuts; P < 0.05), but the anticipated decrease in barrow subcutaneous fat when feeding 5% canola oil was not significant (-4 g kg -1 lean cuts; P > 0.05). No practical differences in pork quality were noted when feeding any diet, but backfat became more unsaturated when feeding canola oil and led to softer backfat (P < 0.05). When feeding canola oil to barrows, it may therefore be more practical to feed higher levels than lower levels due to improvements in animal performance without changes in body composition, but care must be taken so that fat softness does not become an issue. Les truies nullipares recevant 2 % d'huile de canola enregistrent un gain quotidien moyen (GQM) semblable (P > 0,05) à celui des truies nullipares assujetties à un autre régime, mais elles engraissent plus lentement que les castrats absorbant 5 % d'huile de canola (0,99 c. 1,08 kg par jour; P < 0,05) et leur GQM a tendance à être plus bas que celui des castrats nourris avec du suif (P < 0,10). Les castrats recevant 2 % d'huile de canola valorisent moins bien les aliments (kg de nourriture par kg de poids gagné) que les sujets nourris avec une autre ration (P < 0,05). En ce qui concerne les castrats, la ration renfermant 2 % d'huile de canola accroît plus la proportion de graisse sous-cutanée que celle contenant 2,16 % de suif (hausse de 18 g par kg de viande maigre; P < 0,05), mais la baisse de graisse sous-cutanée qu'on anticipait chez les castrats recevant 2 % d'huile de canola au lieu de 5 % n'est pas significative (baisse de 4 g par kg de viande maigre; P > 0,05). On ne relève aucune variation concrète de la qualité de la viande d'une ration à l'autre, mais le gras dorsal perd de sa saturation et de sa fermeté quand les animaux absorbent de l'huile de canola (P < 0,05). Lorsqu'on sert de l'huile de canola aux castrats, il pourrait donc s'avérer plus commode de leur en donner plus que moins, une conce...