Factors Affecting The Reproductive Performance in Gilts: A Field Study
| Autor: | Jing-En Huang, 黃靖恩 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The study comprised 9,520 gilts data from seven commercial swine herds located in southern Taiwan. The purpose of this study was to find the influence of repeat service, type of mating, season of conception, breed of females, and age at conception on reproductive performance of gilts. When repeat services were performed, live born per litter increased from 8.09 to 8.65 and 7.74 to 8.23 (P < 0.01), respectively, in two of the seven herds. Conception rates were found to be improved from 76.67% to 80.21% and 82.65% to 85.57% (P < 0.01), respectively, in the same two herds. Repeat breeding gilts were usually older than those gilts served only the first time, i.e. 60 days older on average. Their reproductive performances were supposed to be no worse than non-repeat breeding gilts. However, the conception rate tended to fall off in four of the five remaining herds. The effect of mating type, AI or natural mating, did not influence reproductive performance except in the smallest herd. The conception rates were 58.33% and 85.57% (P < 0.01) for AI and natural mating, respectively. The differences of average total born and born alive were within a range of 0.3 pigs between AI and natural mating, where AI performed slightly better in most herds. The effect of conception season on born alive was found to be significant statistically in three of the seven herds. Gilts conceived during hot season, from June to September, had more pigs born alive per litter than gilts conceived during moderate season (March, April, May, October, and November) and cold season (December, January, and February). The average born alive in hot season were 0.96, 0.17, and 0.34 head above the cold season (P > 0.05) in herd 1, 3, and 4, respectively. The differences were larger, 1.40, 0.19, 1.58, when hot season was compared to moderate season (P < 0.05). The conception rates, in three of the seven herds, were found to be lower when gilts were conceived during hot season than during cold season. The conception rates were 82.29% vs. 90.83%, 72.97% vs. 77.64%, 79.69% vs. 86.61%, and 72.33% vs. 82.12% (P < 0.05) in these three herds, respectively. When data from seven farms were combined, the Landrace X Yorkshire crossbred gilts had the largest live born and total born litter sizes, 9.08 and 10.04, respectively. On the contrary, Duroc gilts had 7.17 and 8.55 pigs for live born and total born litter sizes, respectively. In three of the six herds recorded birth date data, live born litter size increased 0.0209, 0.0171, and 0.0347 pigs per day, respectively, as the age at conception increased from 215 to 265 days. When data from six herds were combined, born alive were found to increase 0.0175 pigs per day between conception age of 215 and 265 days. When conception took place beyond 265 days of age, litter size did not change in general, except in one herd which had an increase of 0.0285 pig per day from 266 to 315 days of age. It was concluded from the analysis that age at conception, repeat service, type of service, season of conception, and breed of females all had more or less influence on reproductive performance of gilts. However, the associations were variable among herds. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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