Bull selection and use in northern Australia

Holroyd, R. G.; Doogan, V. J.; Faveri, J. De; Fordyce, Geoffry; McGowan, Michael; Bertram, J. D.; Vankan, D.; Fitzpatrick, L.A.; Jayawardhana, G. A.; Miller, Robert G.

doi:10.1016/s0378-4320(02)00026-x

Cited by 78 publications

(32 citation statements)

References 10 publications

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“…The determination of the percentage morphologically normal bull sperm is highly repeatable and is strongly correlated with days to conception and calf output in both dairy herds (1)(2)(3) and beef herds (4). Increasingly, however, bull semen, in collection centers, is often evaluated only for total sperm numbers (concentration) and sperm motility (3).…”

Section: Introductionmentioning

confidence: 99%

The Role of Sperm Morphology Standards in the Laboratory Assessment of Bull Fertility in Australia

Perry

2021

Front. Vet. Sci.

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The lack of standardization in the laboratory assessment of semen questions the reliability of semen analysis, and makes meaningful interpretation of these evaluations impossible. We herein describe a standardization program for morphology assessment currently in place in Australia and outline the methods used, both for the categorization of the abnormalities, including newly described abnormalities, and those that permit standardized microscopic assessment between laboratories.

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Section: Introductionmentioning

confidence: 99%

The Role of Sperm Morphology Standards in the Laboratory Assessment of Bull Fertility in Australia

Perry

2021

Front. Vet. Sci.

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“…Male fertility is of interest to and concerns two distinct fields: clinical medicine, which aims at identifying and treating subfertility, and livestock breeding, which relies on optimal fertility rates for efficient production. Male fertility indicators, such as sperm susceptibility to DNA fragmentation, sperm morphology, or testicular size, are used in a clinical context and, also, to evaluate the breeding capacity of livestock species [ 1 – 3 ]. Fertility indicators are often heritable and represent complex phenotypes that are controlled by multiple genes [ 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…A common abnormality in the bovine sperm is the retention of cytoplasmic droplets that can be proximal or distal to the midpiece. Within this first group of routine phenotypes, the percentage of sperm with normal morphology is considered the best indicator of bull fertility [ 3 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

X chromosome variants are associated with male fertility traits in two bovine populations

et al. 2020

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Background Twenty-five phenotypes were measured as indicators of bull fertility (1099 Brahman and 1719 Tropical Composite bulls). Measurements included sperm morphology, scrotal circumference, and sperm chromatin phenotypes such as DNA fragmentation and protamine deficiency. We estimated the heritability of these phenotypes and carried out genome-wide association studies (GWAS) within breed, using the bovine high-density chip, to detect quantitative trait loci (QTL). Results Our analyses suggested that both sperm DNA fragmentation and sperm protamine deficiency are heritable (h 2 from 0.10 to 0.22). To confirm these first estimates of heritability, further studies on sperm chromatin traits, with larger datasets are necessary. Our GWAS identified 12 QTL for bull fertility traits, based on at least five polymorphisms (P < 10 −8 ) for each QTL. Five QTL were identified in Brahman and another seven in Tropical Composite bulls. Most of the significant polymorphisms detected in both breeds and nine of the 12 QTL were on chromosome X. The QTL were breed-specific, but for some traits, a closer inspection of the GWAS results revealed suggestive single nucleotide polymorphism (SNP) associations (P < 10 −7 ) in both breeds. For example, the QTL for inhibin level in Braham could be relevant to Tropical Composites too (many polymorphisms reached P < 10 −7 in the same region). The QTL for sperm midpiece morphological abnormalities on chromosome X (QTL peak at 4.92 Mb, P < 10 −17 ) is an example of a breed-specific QTL, supported by 143 significant SNPs (P < 10 −8 ) in Brahman, but absent in Tropical Composites. Our GWAS results add evidence to the mammalian specialization of the X chromosome, which during evolution has accumulated genes linked to spermatogenesis. Some of the polymorphisms on chromosome X were associated to more than one genetically correlated trait (correlations ranged from 0.33 to 0.51). Correlations and shared polymorphism associations support the hypothesis that these phenotypes share the same underlying cause, i.e. defective spermatogenesis. Conclusions Genetic improvement for bull fertility is possible through genomic selection, which is likely more accurate if the QTL on chromosome X are considered in the predictions. Polymorphisms associated with male fertility accumulate on this chromosome in cattle, as in humans and mice, suggesting its specialization.

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“…In this study an in utero LPeri diet increased the age at which bulls reach puberty predicated by the motility, morphology and concentration of spermatozoa produced in the ejaculate (Barth and Oko 1989;Perry et al 1990;Holroyd et al 2002). The higher levels of spermatozoa with non-progressive motility, the overall increased numbers of morphologically abnormal spermatozoa and the tendency for lower concentrations suggest that both epididymal function and spermatogenesis were delayed or disrupted by the LPeri maternal diet.…”

Section: Postnatal Developmentmentioning

confidence: 54%

Peri-conception and first trimester diet modifies reproductive development in bulls

Copping

Ruiz-Diaz

Mongan

et al. 2018

Reprod. Fertil. Dev.

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Abstract. Nutritional perturbation during gestation alters male reproductive development in rodents and sheep. In cattle both the developmental trajectory of the feto-placental unit and its response to dietary perturbations is dissimilar to that of these species. This study examined the effects of dietary protein perturbation during the peri-conception and first trimester periods upon reproductive development in bulls. Nulliparous heifers (n ¼ 360) were individually fed a high-or low-protein diet (HPeri and LPeri) from 60 days before conception. From 24 until 98 days post conception, half of each treatment group changed to the alternative post-conception high-or low-protein diet (HPost and LPost) yielding four treatment groups in a 2 Â 2 factorial design. A subset of male fetuses (n ¼ 25) was excised at 98 days post conception and fetal testis development was assessed. Reproductive development of singleton male progeny (n ¼ 40) was assessed until slaughter at 598 days of age, when adult testicular cytology was evaluated. Low peri-conception diet delayed reproductive development: sperm quality was lowered during pubertal development with a concomitant delay in reaching puberty. These effects were subsequent to lower FSH concentrations at 330 and 438 days of age. In the fetus, the low periconception diet increased the proportion of seminiferous tubules and decreased blood vessel area in the testis, whereas low first trimester diet increased blood vessel number in the adult testis. We conclude that maternal dietary protein perturbation during conception and early gestation may alter male testis development and delay puberty in bulls.

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Bull selection and use in northern Australia

Cited by 78 publications

References 10 publications

The Role of Sperm Morphology Standards in the Laboratory Assessment of Bull Fertility in Australia

The Role of Sperm Morphology Standards in the Laboratory Assessment of Bull Fertility in Australia

X chromosome variants are associated with male fertility traits in two bovine populations

Peri-conception and first trimester diet modifies reproductive development in bulls

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