Effects of age, genotype, mating behavior and seminal binding proteins on natural service fertility of bulls /
Experiments were conducted to determine the reproductive
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=743274131&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Experiments were conducted to determine the reproductive potential of herd sires by: 1) evaluation of age, genotype and year effects on semen quality, scrotal circumference and response to electroejaculation, and (2) assessment of the effects of serving capacity and heparin binding profiles on pregnancy rates and conceptus age in multiple-sire breeding pastures. In Experiment 1, Trial I included I- and 2-yr-old bulls of three genotypes: Santa Cruz (n--181, SC), Santa Gertrudis (n--175, SG) and Fl Gelbvieh X Red Angus (n--325, FGVRA) during 2 yr. Trial 2 included 4-, 5-, 6- and 7yr-old bulls of four genotypes: Gelbvieh (n=407, GV), Red Angus (n=455, RA), Santa Gertrudis (n--177, SG) and Simmental (n7- -23 1, SM) during 2 yr. In Trial 1, fewer electrical impulses were required to ejaculate I- than 2-year-old bulls (P<.001). Scrotal circumference was influenced by age and genotype. An age by genotype by year interaction (P<.001) influenced the number of impulses required to elicit ejaculation. SG bulls required more impulses as I -yr-old bulls but required fewer impulses as 2-yrold bulls compared to SC and FGVRA bulls, and more impulses were required in Year 2 than in Year 1. An age by genotype by year effect (P<.05) on sperm motility was observed for the I- and 2- year-old bulls. In Trial 2, fewer impulses were required to ejaculate GV (P<.05) than RA bulls. GV bulls had more (P<.Ol) motile and normal sperm than the SG and SM genotypes. In Experiment 2, Santa Cruz bulls (n--50) were classified as either High (> 2 services, HSC) or Low (:5 1 service, LSC) serving capacity and either High (HHB) or Low (LHB) fertility based upon heparin binding protein profile of sperm. Primiparous cows were joined with HSCHHB (n--12), HSCLHB (n--5) or LSCHHB (n=9) bulls at a 1:25 bull to female ratio for 60 days. Pregnancy rates were enhanced by bulls which combined HSC and HHB profiles (P<.05). Cows joined with HSCHHB bulls conceived earlier (P<.0001) than cows joined with either HSCLHB or LSCHHB bulls. We conclude that yearling bulls respond more rapidly to electroejaculation stimuli than older bulls and that bulls which exhibit both high serving capacity and a high heparin binding profile can enhance pregnancy rates and decrease interval to conception in multiple-sire breeding pastures. |
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| Item Description: | Vita. "Major Subject: Physiology of Reproduction". |
| Physical Description: | xii, 94 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |