Knowledge of carcass merit will help the meat duck breeder identify superior stock and accelerate genetic improvement. Selection for leanness will enhance product acceptance by the consumer. Heritability values for carcass traits are in the medium-high range. Feed intake level during rearing is critical for reproduction. The objectives were to evaluate (1) the response of breast muscle thickness of the F1 progeny from parent breeders selected for maximum muscle thickness at market age and (2) the effect of 2 levels of feed restriction during development for subsequent egg production. In a commercial flock, 4842 Pekin ducks (Brome Lake Ducks Ltd.) were individually weighed and measured by ultrasound for breast muscle thickness (MT, mm) at 47 days of age. Three groups of 120 females and 25 males each were selected and allocated to the following groups: (1) control (CT), randomly selected; (2) maximum body weight (BW), and (3) maximum MT. From 7 to 23 wk old, one half of breeders followed a conventional restriction (CR) at 67 g feed/kg body weight daily, the other half were slightly more restricted following a Macdonald restriction (MR) at the same intake as CR but with a weekly skip-a-day feeding. (Abstract shortened by UMI.)

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Peroxisome proliferator-activated receptor (PPARy) is a transcription factor that regulates adipogenic genes and preadipocyte factor-1 (pref-1) is a transmembrane protein that regulates preadipocyte differnetiation. The role of PPARy was investigated using reverse transcription polymerase chain reaction (RT-PCR) by measuring PPARy mRNA levels in bovine adipose depots and longissimus dorsi muscle. No significant differences in PPARy mRNA levels were observed between 10 Charolais and 10 Holstein cattle for either tissue. Differences were observed between depots within these breeds. Correlations were performed among PPARy, carcass characteristics, and adipogenic genes. Pref-1 antibodies were used to immunolocate preadipocytes in bovine muscle tissue to the perimycium, near fat cells and blood vessels. The preadipocytes may exist in muscle tissue for short periods of time or may arise from a source external to the muscle. A computer image analysis program was developed for the quanitifaction and characterization of intramuscular fat in whole muscle tissues. / xvi, 154 leaves : ill. (some col.) ; 28 cm.

Four experiments were conducted to determine the reproductive, metabolic, growth and IGF-I response to ultrasound selection for increased breast muscle thickness (MT) in Pekin ducks. Selection for body weight had a negative ( P < 0.05) effect on the reproductive performance while the selection for greater breast muscle thickness resulted in egg production, fertility and hatchability similar to those of the control line (C). Males from the MT line reached market weight at 6 wk but the breast muscle thickness improved from 6 to 7 wk. Compared to females from the C line, MT females had higher (P < 0.05) carcass yield, plasma glucose, and body protein; lower fat and plasma uric acid; and no difference (P > 0.05) in plasma triglycerides and total cholesterol. Males responded more efficiently to increasing dietary protein than females, and males selected for greater MT can be slaughtered at an earlier age when a high protein feeding program (HP) was followed. Males receiving HP had greater (P < 0.05) pectoralis muscles yield, longer keel bone, and lower breast skin and total skin fat yields. Female dissection data show similar (P > 0.05) effects of high and medium protein programs. Increasing dietary protein reduced (P < 0.05) carcass fat and increased (P < 0.05) crude protein (CP). In vivo breast muscle measurement correlated positively (P < 0.05) with body weight, pectoralis yield, and keel bone length. Birds with higher pectoralis yield tended to have more CP and less fat in their carcasses. A low correlation (r = 0.19) was found for the caliper measurement of breast skin plus fat thickness and carcass fat. We determined the metabolic differences between lean and fat male and female ducks, associated metabolic parameters and body composition, and assessed the difference between two feeding solutions for the determination of metabolic endogenous losses. There was a positive correlation between breast muscle:total breast muscle thickness ratio (MT/TO

The effects of dietary fat on the reproductive performance of broiler breeder chickens have been studied. Individually caged broiler breeders were fed diets with or without added fat during 19-wk reproductive period. In Experiment 1, only the females were subjected to dietary treatments: control (no added fat), 3% animal-vegetable fat blend (A-V fat, 3% corn oil (CO)), while the males received a non-added fat diet. In Experiment 2, only the males were fed diets containing 0 or 3% of either A-V fat or CO while the females were provided a non-added-fat diet. / In Experiment 1, added dietary fat produced significantly higher fertility and early embryonic livability. In Experiment 2, inclusion of 3% CO in the males' diets significantly increased late embryo livability and total embryo survival resulting in a significantly higher hatchability. There were no differences in semen characteristics among dietary treatments. These data indicate that the contribution of the male is not restricted to the fertilization of eggs but is also related to embryonic livability. The addition of fat significantly affected the fatty acid composition of the phospholipid fraction of the spermatozoa cells.

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The objectives of this research were (1) to study the relative ability of genetically different types of domestic chickens to digest and absorb fat of different types, and (2) to relate fat absorbability coefficients to dietary apparent M. E. values obtained with genetically different types of chickens feeding on diets containing the different types of fat, (3) to search for a possible cause of poultry genetic difference in fat absorbability by examining some of the factors most likely to influence fat digestion and absorption in the genetically different types of chickens. Using New Hampshire, White Leghorn and broiler-type birds, it was found that until 6 weeks of age the New Hampshires were significantly (P≤0.05) superior to the others in their ability to utilize animal tallow. Differences among birds in the absorbability of corn oil were small. Differences in dietary M.E. estimates were closely associated with differences in fat absorbability values and on a 12% tallow diet, the R² values computed on a within age between breeds basis, were 0.67, 0.36 and 0.022 at 3, 5, and 9 weeks of age respectively. This general decline in R² values was a reflection of the narrowing of the range of fat absorbability differences among different types of birds as they grew older. The overall conclusion based on these results, is that breed and/or age differences in M.E. estimates are to a large extent attributable to breed and/or age differences in the absorbability of dietary lipid materials. The search for potential causes of the observed breed differences in fat absorbability was therefore the main theme of the subsequent experiments. A study of the feed passage time in birds of different genetic backgrounds failed to provide any conclusive evidence on whether or not breed differences in ingesta transit time are in measureable terms responsible for fat absorbability differences. It was found, however, that with diets containing 12% of animal tallow or corn oil, feed passage time was significantly longer regardless of the type of birds. On the basis of the results of an experiment in which in vitro pancreatic lipase activity was measured, the New Hampshires ranked first followed by Broilers and White Leghorns in that order. However, the magnitude of differences among them was small. Supplementation of the 12% tallow diet with the bile salt, sodium taurocholate, improved fat utilization significantly by the broiler-type and White Leghorn chicks to the extent of 8.6% and 7.2% respectively. The improvement in fat absorbability was associated with a significant reduction in the amount of fecal soap fatty cacids. The effect of the sodium taurocholate suggested that in the Broilers and White Leghorn chicks, the supply of bile salts was below the critical micellar concentration required for efficient tallow fat absorption. Results from a general study on intestinal fatty acid binding protein (FABP) revealed that a fatty acid binding protein in the same molecular weight range as that one demonstrated in the rat, exists in the intestinal mucosa of the adult chickens and in the mesenteric intestine of day-old chicks prior to the ingestion of any feed. / Land and Food Systems, Faculty of / Graduate