Selection for fertility traits in Brahmans increases heifer pregnancy rates from yearling mating

Schatz, T. J.; Jayawardhana, G. A.; Golding, R.; Hearnden, M. N.

doi:10.1071/an09165

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…Nevertheless, age at first calving is favorably genetically associated with heifer rebreeding [ 66 ]. Schatz et al [ 67 ] showed that selection for fertility increases pregnancy rates of heifers exposed to reproduction at yearling in tropical conditions. In order to achieve reproductive efficiency, it is key to find the proper balance between sexual precocity and weight gain selection [ 68 ].…”

Section: The Genetics Of Heifers Sexual Precocitymentioning

confidence: 99%

Sustainable Intensification of Beef Production in the Tropics: The Role of Genetically Improving Sexual Precocity of Heifers

Júnior

Silva

Mota

et al. 2022

Animals

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Increasing productivity through continued animal genetic improvement is a crucial part of implementing sustainable livestock intensification programs. In Zebu cattle, the lack of sexual precocity is one of the main obstacles to improving beef production efficiency. Puberty-related traits are complex, but large-scale data sets from different “omics” have provided information on specific genes and biological processes with major effects on the expression of such traits, which can greatly increase animal genetic evaluation. In addition, genetic parameter estimates and genomic predictions involving sexual precocity indicator traits and productive, reproductive, and feed-efficiency related traits highlighted the feasibility and importance of direct selection for anticipating heifer reproductive life. Indeed, the case study of selection for sexual precocity in Nellore breeding programs presented here show that, in 12 years of selection for female early precocity and improved management practices, the phenotypic means of age at first calving showed a strong decreasing trend, changing from nearly 34 to less than 28 months, with a genetic trend of almost −2 days/year. In this period, the percentage of early pregnancy in the herds changed from around 10% to more than 60%, showing that the genetic improvement of heifer’s sexual precocity allows optimizing the productive cycle by reducing the number of unproductive animals in the herd. It has a direct impact on sustainability by better use of resources. Genomic selection breeding programs accounting for genotype by environment interaction represent promising tools for accelerating genetic progress for sexual precocity in tropical beef cattle.

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Section: The Genetics Of Heifers Sexual Precocitymentioning

confidence: 99%

Sustainable Intensification of Beef Production in the Tropics: The Role of Genetically Improving Sexual Precocity of Heifers

Júnior

Silva

Mota

et al. 2022

Animals

View full text Add to dashboard Cite

show abstract

“…An important, overarching limitation continues to be nutritional and other environmental constraints on genetic expression of selected traits. Nevertheless, selection-line experiments have demonstrated that significant improvement in reproduction rates is possible in Droughtmaster (Davis et al 1993) and Brahman (Schatz et al 2010) breeds, as has the practical experience of astute and well-informed producers such as Alf Collins (Anon 2019). Recently, the genetic bases for these outcomes have become much better understood through research conducted by the CRC for Beef Genetic Technologies, particularly on defining the degree of genetic control for component physiological traits that underpin overall reproductive performance.…”

Section: Challenges and Opportunities For Genetic Improvement Of Repr...mentioning

confidence: 99%

Research, development and adoption for the north Australian beef cattle breeding industry: an analysis of needs and gaps

Bell

Sangster

2022

Anim. Prod. Sci.

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This review seeks to analyse and prioritise needs and gaps in research and development (R&D) for the north Australian beef cattle breeding industry, and to advise on options to increase rates of adoption and successful implementation of this R&D. The material reviewed includes the peer-reviewed literature as well as industry reports and other relevant publications in three targeted areas of R&D deemed to be important by industry leaders and supporting scientists: (i) breeding herd management, (ii) feedbase management, and (iii) management of environmental sustainability. For breeding herd management, the need for uniform definition and consistent utilisation of appropriate productivity metrics is highlighted, with emphasis on assessment of maternal reproductive efficiency in terms of weaning (or branding) rates. Priority is given to the urgent need for reliable means of remotely assessing causes of neonatal calf mortality to enable the development and application of management interventions that improve calf survival rates. The highest priority for feedbase management is to increase producer awareness and willingness to adopt stocking rates that are appropriately matched to the long-term carrying capacity of native rangeland pastures that predominate in northern Australia. Other opportunities include increasing the use of perennial, tropically adapted legumes, where conditions permit, to improve soil fertility and nitrogen intake of cattle, and devising strategies to overcome widespread phosphorus deficiency through diagnosis and supplementation, especially in the wet season. In order to enhance environmental sustainability in the face of climate change, priorities include improving producer awareness and use of increasingly robust tools for predicting key weather events, as well as developing genetic strategies to increase heat tolerance of cattle and evaluating management interventions to mitigate heat stress. Conclusions drawn from these sections are summarised and used to make recommendations on priorities for increasing adoption of existing research-proven practices and technologies, and for further R&D on selected topics.

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“…Genetic improvement programs for female fertility in beef cattle has been hindered by the difficulty of collecting accurate fertility-related phenotypes needed to improve the predictive ability of genomic selection models (Tiezzi and Maltecca 2011). Some nucleus herds (or research stations) are capable of collecting very detailed, accurate and sometimes expensive fertility phenotypes (Schatz et al 2010). However, the size from these nucleus herds tends to be relatively small and sample size affects the predictive power of genomic selection.…”

Section: Table 6 Genomic Correlations Estimated Between Cow and Bull Fertility Traits In Brahman Andmentioning

confidence: 99%

Genetic parameter estimates for male and female fertility traits using genomic data to improve fertility in Australian beef cattle

et al. 2021

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Context. Studies have shown that favourable genetic correlations exist between female and male fertility traits. However, investigations regarding these correlations in Australian tropical beef cattle are limited to either pedigree or single-breed analysis.Aim. The study aims to use genomic information to estimate genetic parameters of six female and seven male fertility traits measured during the first 2 years of life, in two tropical breeds.Methods. Single-, bivariate and multi-trait models were used to analyse fertility data from Brahman (BB; 996 cows and 1022 bulls); and Tropical Composite (TC; 1091 cows and 998 bulls) cattle genotyped with high-density singlenucleotide polymorphism chip assay.Key results. Heritability estimates in BB cows ranged from low (0.07 AE 0.04) for days to calving at the first calving opportunity (DC1, days) to high (0.57 AE 0.08) for age at first corpus luteum (AGECL, days). In BB bulls, estimates varied from low (0.09 AE 0.05) for sperm motility (score 1-5) to high (0.64 AE 0.06) for scrotal circumference (SC) measured at 24 months (SC24, cm). Similarly, heritability estimates in TC cows were low (0.04 AE 0.03) for DC1 and high (0.69 AE 0.02) for AGECL. In TC bulls, the heritability was low (0.09 AE 0.05) for sperm motility and high (0.69 AE 0.07) for SC24. Within-sex for both breeds, blood concentrations of insulin growth-factor 1 (IGF1) measured in cows at 18 months (IGF1c) were negatively correlated with female fertility phenotypes. In BB, across-sex, bulls' blood concentration of IGF1 measured at 6 months (IGF1b) was a good indicator trait for the following four female traits: AGECL, the first postpartum anoestrus interval, age at first calving and DC1. In TC, IGF1b and percentage normal sperm were good predictors of female fertility phenotypes.Conclusions. The heritability estimates and genomic correlations from the present study generally support and confirmed the earlier estimates from pedigree analyses. The findings suggest that selection for female fertility traits will benefit male fertility, and vice versa.Implications. Heritability estimates and genomic correlations suggest that we can select for fertility traits measured early in life, with benefits within and across sex. Using traits available through veterinary assessment of bull fertility as selection indicators will enhance bull and cow fertility, which can lead to better breeding rates in tropical herds.

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Selection for fertility traits in Brahmans increases heifer pregnancy rates from yearling mating

Cited by 9 publications

References 15 publications

Sustainable Intensification of Beef Production in the Tropics: The Role of Genetically Improving Sexual Precocity of Heifers

Sustainable Intensification of Beef Production in the Tropics: The Role of Genetically Improving Sexual Precocity of Heifers

Research, development and adoption for the north Australian beef cattle breeding industry: an analysis of needs and gaps

Genetic parameter estimates for male and female fertility traits using genomic data to improve fertility in Australian beef cattle

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