Correlated responses to selection for cow fertility in a tropical beef herd

Mackinnon, M. J.; Hetzel, D. J. S.; Corbet, N. J.; Bryan, R.P.; Dixon, R. M.

doi:10.1017/s0003356100004906

Cited by 30 publications

(7 citation statements)

References 14 publications

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“…Age‐corrected scrotal circumference was consistently reported to be a useful method of assessing reproductive function in bulls (Table 1) because of the favourable relationship with a number of sperm traits (Brinks et al. 1978) and fertility (Mackinnon et al. 1990b).…”

Section: Resultsmentioning

confidence: 99%

“…Genetic markers of male reproductive traits with effects on female progeny. Age-corrected scrotal circumference was consistently reported to be a useful method of assessing reproductive function in bulls (Table 1) because of the favourable relationship with a number of sperm traits (Brinks et al 1978) and fertility (Mackinnon et al 1990b). Prepubertal basal serum follicle-stimulating hormone (FSH) concentration was identified as a potential candidate trait because of its role in the endocrine control of testicular function and its moderate correlation with Sertoli cell number (Moura and Erickson 1997) (Table 1).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Male Reproductive Traits and Their Relationship to Reproductive Traits in Their Female Progeny: A Systematic Review

Burns

Gazzola²,

Holroyd³

et al. 2011

Reprod Domestic Animals

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The overall objective of one of the major research programs in the Co-operative Research Centre (CRC) for Beef Genetic Technologies is to 'Improve female reproductive performance' in tropical, northern Australian beef cattle herds. To address this overall objective, a quantitative genetics project focused on investigation of male reproductive traits was designed and linked to three female reproduction-focussed projects, (i) discovery of genes associated with post-partum re-conception and age at puberty; (ii) expression of genes associated with post-partum re-conception; and (iii) early predictors of lifetime female reproductive performance. During the initial planning of this male reproductive traits project, the CRC Scientific Review Committee recommended that the research team investigate and evaluate potentially new, early-life (i.e able to be measured before 2 years of age) predictors of both male and female reproductive performance. To address this recommendation, the following was carried out: (i) criteria for selection of traditional and candidate traits were established; (ii) methodology for tabulation of potential traits/phenotypes that define male and female reproductive function was developed; and (iii) a systematic scientific review of early-life predictors of male and female fertility was prepared. This review concluded that although factors that might be useful in predicting male reproductive performance have been studied for many years, there was relatively little useful information available to meet the objectives of this review. It was also concluded that the direction of future research should be guided not only by previous research which was scarce, but also by speculative hypotheses arising from an understanding of the physiological, endocrinological and genetic processes active in reproduction. A small number of new traits were recommended in addition to traditional sperm morphology, sexual behaviour, anatomical structure and growth traits. Potential additional traits include measurement of gonadotrophin-releasing hormone-stimulated luteinizing hormone (GnRH-stimulated LH); inhibin; several seminal plasma proteins (osteopontin, spermadhesin and seminal plasma proteins BSP30 and phospholipase A(2) could be used in an index); 11β-hydroxysteriod dehydrogenase; and leptin. In addition, the potential also exists to screen animals for a number of genetic markers associated with age of puberty, follicular recruitment and ovulation rate and genes associated with bovine seminal plasma protein and testosterone production. Insulin-like growth factor-1 (IGF-1) measurements are included because of their association with growth parameters, and an additional analysis demonstrated associations with male and female reproductive traits. Some of these factors have been previously evaluated in small numbers of animals of various species under intensive management conditions. Therefore, there is a need to evaluate these factors in much larger numbers of beef cattle grazing semi-extensive tropical production syste...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Male Reproductive Traits and Their Relationship to Reproductive Traits in Their Female Progeny: A Systematic Review

Burns

Gazzola²,

Holroyd³

et al. 2011

Reprod Domestic Animals

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“…Changes in female reproductive characteristics by selection in the prepubertal ram for high LH response to GnRH challenge were demonstrated in sheep (Evans et al, 1989) and may exist in cattle as there is genetic variation (h 2 > 0.5) between young bulls in their ability to secrete testosterone in response to GnRH stimulation (Mackinnon et al, 1991). These genetically influenced hormonal control mechanisms coupled with reports that fertility is repeatable (Rudder et al, 1976;Goddard, 1980;Seifert et al, 1980;Entwistle, 1983Entwistle, , 1984Winter et al, 1985;Mackinnon, 1988;Mackinnon et al, 1987;O'Neill et al, 2000) suggest that an opportunity exists to genetically improve calf output in tropical genotypes in northern Australia, partly by reducing reproductive inefficiencies.…”

Section: Genetic Factors Associated With Reproductive Efficienciesmentioning

confidence: 99%

A review of factors that impact on the capacity of beef cattle females to conceive, maintain a pregnancy and wean a calf—Implications for reproductive efficiency in northern Australia

Burns

Fordyce²,

Holroyd

2010

Animal Reproduction Science

133

128

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A review of factors that may impact on the capacity of beef cattle females, grazing semi-extensive to extensive pastures in northern Australia, to conceive, maintain a pregnancy and wean a calf was conducted. Pregnancy and weaning rates have generally been used to measure the reproductive performance of herds. However, this review recognises that reproductive efficiency and the general measures associated with it more effectively describe the economic performance of beef cattle enterprises. More specifically, reproductive efficiency is influenced by (1) pregnancy rate which is influenced by (i) age at puberty; (ii) duration of post-partum anoestrus; (iii) fertilisation failure and (iv) embryo survival; while (2) weight by number of calves per breeding female retained for mating is influenced by (i) cow survival; (ii) foetal survival; and (iii) calf survival; and (3) overall lifetime calf weight weaned per mating. These measures of reproductive efficiency are discussed in depth. Further, a range of infectious and non-infectious factors, namely, environmental, physiological, breed and genetic factors and their impact on these stages of the reproductive cycle are investigated and implications for the northern Australian beef industry are discussed. Finally, conclusions and recommendations to minimise reproductive inefficiencies based on current knowledge are presented.

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“…Mackinnon et al 1989;Prayaga 2004). The review of Davis (1993) identified significant within-breed genetic differences for female reproduction traits related to calf output, and results from a large divergent selection study for pregnancy rate in a tropical beef herd generated significant differences in pregnancy rate between the high and low lines Mackinnon et al 1990;Davis et al 1993). However, industry-wide improvement of female reproductive performance by genetic selection has generally proved difficult, mainly because of low heritabilities and the late expression of traits, and difficulties in capturing the necessary joining and reproductive data.…”

Section: Introductionmentioning

confidence: 99%

“…However, results are inconclusive. Several studies have shown improved pregnancy or calving rates to be associated with the age at puberty Morris et al 2000;Phocas and Sapa 2004) and Mackinnon et al (1990) postulated the selection response in female fertility in a divergently selected tropical beef herd was likely due to earlier sexual maturity. Mialon et al (2001) showed a positive genetic correlation between the age at the first oestrous and the postpartum to return to oestrus interval.…”

Section: Introductionmentioning

confidence: 99%

Genetics of heifer puberty in two tropical beef genotypes in northern Australia and associations with heifer- and steer-production traits

et al. 2009

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Abstract.A total of 2115 heifers from two tropical genotypes (1007 Brahman and 1108 Tropical Composite) raised in four locations in northern Australia were ovarian-scanned every 4-6 weeks to determine the age at the first-observed corpus luteum (CL) and this was used to define the age at puberty for each heifer. Other traits recorded at each time of ovarian scanning were liveweight, fat depths and body condition score. Reproductive tract size was measured close to the start of the first joining period. Results showed significant effects of location and birth month on the age at first CL and associated puberty traits. Genotypes did not differ significantly for the age or weight at first CL; however, Brahman were fatter at first CL and had a small reproductive tract size compared with that of Tropical Composite. Genetic analyses estimated the age at first CL to be moderately to highly heritable for Brahman (0.57) and Tropical Composite (0.52). The associated traits were also moderately heritable, except for reproductive tract size in Brahmans (0.03) and for Tropical Composite, the presence of an observed CL on the scanning day closest to the start of joining (0.07). Genetic correlations among puberty traits were mostly moderate to high and generally larger in magnitude for Brahman than for Tropical Composite. Genetic correlations between the age at CL and heifer-and steer-production traits showed important genotype differences. For Tropical Composite, the age at CL was negatively correlated with the heifer growth rate in their first postweaning wet season (-0.40) and carcass marbling score (-0.49), but was positively correlated with carcass P8 fat depth (0.43). For Brahman, the age at CL was moderately negatively genetically correlated with heifer measures of bodyweight, fatness, body condition score and IGF-I, in both their first postweaning wet and second dry seasons, but was positively correlated with the dry-season growth rate. For Brahman, genetic correlations between the age at CL and steer traits showed possible antagonisms with feedlot residual feed intake (-0.60) and meat colour (0.73). Selection can be used to change the heifer age at puberty in both genotypes, with few major antagonisms with steer-and heifer-production traits.

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Correlated responses to selection for cow fertility in a tropical beef herd

Cited by 30 publications

References 14 publications

Male Reproductive Traits and Their Relationship to Reproductive Traits in Their Female Progeny: A Systematic Review

Male Reproductive Traits and Their Relationship to Reproductive Traits in Their Female Progeny: A Systematic Review

A review of factors that impact on the capacity of beef cattle females to conceive, maintain a pregnancy and wean a calf—Implications for reproductive efficiency in northern Australia

Genetics of heifer puberty in two tropical beef genotypes in northern Australia and associations with heifer- and steer-production traits

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