Genetic and phenotypic analysis of liveweight maturing patterns and their relationship to ewe productivity in Columbia, Rambouillet and Targhee sheep.
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| Format: | Thesis Book |
| Language: | English |
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1983.
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| Online Access: | Link to ProQuest Copy Link to OAKTrust copy |
| Abstract: | One thousand one hundred nine ewes were utilized in a study to investigate growth and maturing patterns of sheep and their relationship to fleece and lamb production. This study furnishes information on growth and maturing patterns not previously reported in the literature, including absolute growth rate (AGR), measured in kg/day and relative growth rate (RGR) and absolute maturing rate (AMR), both measured in percent per day. Five age intervals were included, birth to weaning, weaning to 12 months, 12 months to 18 months, birth to 12 months and birth to 18 months. Degree to maturity was calculated as the proportion of mature size attained at a specific time or age. Reproductive performance and grease fleece weights were recorded starting with the 2-year old record. Mature weight was estimated to be 70.1 kg, 73.2 kg and 72.3 kg respectively, for Rambouillet, Targhee and Columbia breeds. Heritability of mature weight was estimated to be .53 (+OR-) .12. Heritability estimates for degree of maturity ranged from .19 to .63. Degree of maturity at birth was .064 (+OR-) .009, .53 (+OR-) .06 at weaning, .67 (+OR-) .073 at 12 months and .87 (+OR-) .063 at 18 months of age. Measures of growth rate were highest in the birth to weaning interval and were .26 kg/day (AGR), 1.66% (RGR) and .36% (AMR). Growth rate measurements were lowest in the interval weaning to 12 months, and were .04 kg/day (AGR), .10% (RGR) and .06% (AMR). Early maturing animals gained faster until 12 months of age, but their mature weights in proportion to their 12 months weight were less than for later maturing animals. The rates AGR and AMR for the age interval birth to 12 months were correlated positively with 12 month weight. Heritability estimates for production characters were .42 (+OR-) .12 for number of lambs born, .31 (+OR-) .11 for average grease fleece weight and .03 (+OR-) .10 for average kilograms of lamb weaned. All production characters were correlated positively to degree of maturity at birth, 12 months and 18 months of age. Maturing rates were moderately correlated to production characters. |
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| Item Description: | "Major subject: Animal Science." Typescript (photocopy). Vita. |
| Physical Description: | xi, 112 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 71-77). |