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. 1997. The effects of porcine somatotropin, gender and porcine stress syndrome on growth, carcass composition and pork quality. Can. J. Anim. Sci. 77: 233-240. Lacombe breed pigs (72 gilts, 72 barrows) of three genotypes with respect to the porcine stress syndrome (normal, heterozygous, or homozygous for the halothane gene), were treated from 57 to 106 kg body weight with daily injections of 0.9% saline containing 0 or 3 mg of recombinant porcine somatotropin (pST) in a randomized block design. Pigs receiving pST had lower average daily feed intakes (ADF), greater average daily gains (ADG) and lower feed conversion efficiencies (FCE). Gilts relative to barrows had lower ADG, ADF and higher FCE. Gilts versus barrows and pigs treated with pST had reduced fat depths and greater loin depths at the 10th rib. Pigs homozygous for the halothane gene had reduced loin lean structure and color scores, greater light reflectance (L * ), and lower soluble protein contents as expected, and these genotypic effects did not interact with pST treatment. Sex by pST treatment interactions (P < 0.05) were found for loin depth, moisture content, color score and L * values indicating barrows respond more favorably to pST treatment than gilts. Generally, pST treatment, gilts relative to barrows, and possession of the halothane gene increased carcass lean and reduced subcutaneous fat levels. Sex by pST treatment interactions were found for picnic lean (lower shoulder; P < 0.05), ham lean (P < 0.05), and total carcass lean (P = 0.09) further supporting the theory that barrows benefit more than gilts to pST treatment. No significant interactions were found between genotype and pST treatment for any qualitative muscle traits. Thus, pST treatment had no direct effect on meat quality and was not found to interact with the halothane gene. However, pST interactions with sex indicated barrows respond quantitatively and qualitatively more favorably than gilts to pST treatment.Key words: Somatotropin, porcine somatotropin, pork, porcine stress syndrome, stress, pigs, growth Dugan, M. E. R., Tong, A. K. W., Carlson, J. P., Schricker, B. R., Aalhus, J. L., Schaefer, A. L., Sather, A. P., Murray, A. C. et Jones, S. D. M. 1997. Effets de la somatotropine porcine, du genre et du syndrome du stress porcin sur la croissance, sur la composition de la carcasse et sur la qualité de la viande chez le porc. Can. J. Anim. Sci. 77: 233-240. Des porcs de race Lacombe, 72 cochettes et 72 castrats, appartenant à trois génotypes différents selon la sensibilité au syndrome du stress porcin (normal, hétérozygote ou homozygote pour le gene de sensibilité à l'halothane) ont reçu, à partir du poids de 57 jusqu'à celui de 106 kg, des injections journalières d'un soluté à 0,9 % contenant 0 ou 3 mg de somatotropine porcine recombinante (rbST). L'expérience était conduite selon un dispositif aléatoire par blocs. Les sujets recevant la rbST manifestaient un taux d'ingestion moyen (T.I.) plus bas, un meilleur GMQ et un moindre indice de conversion (IC). Par rapport aux castr...

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Records on 4,355 boars sold from 1973 to 1978 at central test stations in Ames, Ida Grove and Lisbon, Iowa, and Clarkson, Nebraska, were evaluated for the relative economic emphasis buyers place on performance traits. Performance traits included days to 104 kg, average daily gain, feed efficiency, backfat thickness and loineye area. Average sale prices were highest for Landrace ($457) and lowest for Berkshire ($340) boars. Highest prices were paid for boars sold at the Ames Station. R2 values from models used to predict sale price for the different breeds ranged from .21 to .49, indicating that variation in sale price was affected by factors other than performance, year-season or location of the test. Relative importance of performance traits varied, with buyers placing more emphasis on backfat and average daily gain than on feed efficiency. Comparison of relative economic weights used in selection indexes against the economic emphasis shown by buyers demonstrated that buyers are placing considerably less emphasis on feed efficiency relative to the other traits than the index suggests. Swine producers could make more progress in improving performance traits if they placed more emphasis on performance traits when purchasing centrally tested boars. Performance traits included days to 104 kg, average daily gain, feed efficiency, backfat thickness and loineye area. Average sale prices were highest for Landrace ($457) and lowest for Berkshire ($340) boars. Highest prices were paid for boars sold at the Ames Station. R 2 values from models used to predict sale price for the different breeds ranged from .21 to .49, indicating that variation in sale price was affected by factors other than performance, year-season or location of the test. Relative importance of performance traits varied, with buyers placing more emphasis on backfat and average daily gain than on feed efficiency. Comparison of relative economic weights used in selection indexes against the economic emphasis shown by buyers demonstrated that buyers are placing considerably less emphasis on feed efficiency relative to the other traits than the index suggests. Swine producers could make more progress in improving performance traits if they placed more emphasis on performance traits when purchasing centrally tested boars.