Influence of season of birth on growth and reproductive development of Brahman bulls

Tatman, Shawn R; Neuendorff, D. A.; Wilson, Timothy W.; Randel, R.D.

doi:10.1016/j.theriogenology.2003.07.027

Cited by 21 publications

(13 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Bonsmara bulls were 12 mo of age, whereas the Angus and Santa Gertrudis bulls were between 14 and 15 mo of age when BSE examinations were conducted. Normal sperm percentages measured in this study were within the range of 44% to 90% reported by Fields et al (1982) and Tatman et al (2004) for bulls of similar age. Progressive sperm motility ranged from 23.7% for Bonsmara bulls in Trial 1 to 48.2% for Angus bulls in Trial 2, which was within the range of 8% to 60% reported in previous studies (Fields et al, 1982;Tatman et al, 2004).…”

Section: Resultssupporting

confidence: 73%

Relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls

Hafla

Lancaster

Carstens

et al. 2012

Journal of Animal Science

View full text Add to dashboard Cite

A meta-analysis was conducted to examine phenotypic relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls. Data evaluated were obtained from 5 postweaning trials involving Angus (n = 92), Bonsmara (n = 62), and Santa Gertrudis (n = 50) bulls fed diets that ranged from 1.70 to 2.85 Mcal ME/kg DM. After an adaptation period of 24 to 28 d, feed intake was measured daily, and BW was measured at 7- or 14-d intervals during the 70- to 77-d trials. Ultrasound carcass traits (12th-rib back fat thickness, BF; LM area, LMA) and scrotal circumference (SC) were measured at the start and end of each trial. Semen samples were collected by electroejaculation within 51 d of the end of the trials when the age of bulls averaged from 365 to 444 d and were evaluated for progressive sperm motility and morphology. Residual feed intake (RFI) was calculated as the difference between actual DMI and expected DMI from linear regression of DMI on ADG and midtest BW(0.75), with trial, trial by ADG, and trial by midtest BW(0.75) as random effects. Across all studies, bulls with low RFI phenotypes (<0.5 SD below the mean RFI of 0) consumed 20% less DM and had 10% less BF but had similar ADG, SC, and semen quality traits compared with high-RFI bulls (>0.5 SD above the mean RFI of 0). Gain to feed ratio was strongly correlated with ADG (0.60) and weakly correlated with initial BW (-0.17) and DMI (-0.26). Residual feed intake was not correlated with ADG, initial age, or BW but was correlated with DMI (0.71), G:F (-0.70), and BF (0.20). Initial SC (-0.20), gain in SC (-0.28), and percent normal sperm (-0.17) were correlated with G:F, but only sperm morphology was found to be weakly associated with RFI (0.13). These data suggest that RFI is not phenotypically associated with SC or sperm motility but is weakly associated with sperm morphology.

show abstract

Section: Resultssupporting

confidence: 73%

Relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls

Hafla

Lancaster

Carstens

et al. 2012

Journal of Animal Science

View full text Add to dashboard Cite

show abstract

“…1959) and season of birth (Aravindakshan et al. 2000a; Tatman et al. 2004) can also influence reproductive development.…”

Section: Regulation Of Gonadotropin Secretion During Developmentmentioning

confidence: 99%

“…Fall born bull calves reached puberty later (Tatman et al. 2004) or the timing of puberty was more variable (Aravindakshan et al.…”

Section: Regulation Of Gonadotropin Secretion During Developmentmentioning

confidence: 99%

Sexual Maturation in the Bull

Rawlings

Evans

Chandolia

et al. 2008

Reprod Domestic Animals

View full text Add to dashboard Cite

In this review, we describe the process of sexual maturation in the bull calf. The testes of the bull grow relatively slowly until approximately 25 weeks of age and then a rapid phase of growth occurs until puberty, at 37-50 weeks of age. During the early postnatal phase of slower growth of the testis pre-spermatogonia and some spermatogonia are established, adult Leydig cells appear and undifferentiated Sertoli cells are produced. The rapid testicular growth, after 25 weeks of age, consists of marked increases in the diameter and length of the seminiferous tubules, dramatic proliferation and differentiation of germ cells, with mature spermatozoa occurring between 32 and 40 weeks of age. The adult Leydig cell population is largely in place by 30 weeks of age and that of Sertoli cells by 30-40 weeks of age. Serum concentrations of LH increase from 4 to 5 weeks of age, to an early postnatal peak at 12-16 weeks of age, followed by a decline to 25 weeks of age. Serum FSH concentrations are high postnatally, declining to approximately 25 weeks of age. Serum testosterone concentrations increase during the phase of rapid testicular growth. Hypothalamic opioidergic inhibition may abate transiently to allow the early postnatal increase in LH secretion, while testicular androgenic negative feedback probably contributes to the decline in gonadotropin secretion to 25 weeks of age. Several lines of study have led us to suggest that early postnatal gonadotropin secretion is pivotal in initiating the process of sexual maturation in the bull calf.

show abstract

“…The animals included in the trial were Brahman ( n = 592) and Tropical Composite ( n = 538) mature bulls. To be included, each bull had to have a complete bull breeding soundness exam dataset including a semen sample collected using electroejaculation between 21 and 25 months of age (to ensure sexual maturity Tatman et al ., ; Burns et al ., ) in the November to October collection period (to reduce seasonal variation), sperm morphology data, and one snap‐frozen sample available for SCSA and SPDA. It was found retrospectively that some samples did not have associated morphology assessments conducted.…”

Section: Methodsmentioning

confidence: 99%

Morphological defects, sperm DNA integrity, and protamination of bovine spermatozoa

2018

View full text Add to dashboard Cite

The association between sperm morphology characteristics and DNA conformation and integrity is still controversial. In bulls, major morphological sperm abnormalities have been associated with reduced fertility, and morphological assessment is used to provide an indication of potential fertility of the individual. Sperm DNA fragmentation and damage has a negative effect on embryo development and subsequently fertility, with bull spermatozoa generally displaying low levels of DNA damage and tight chromatin. However, sensitive methods for detecting chromatin damage may reveal associations with morphological defects. The objective was to determine whether morphological sperm abnormalities and variables expressing sperm DNA integrity and protamination are correlated in bulls, using the sperm chromatin structure assay (SCSA) and the sperm protamine deficiency assay (SPDA). Electroejaculated samples (n = 1009) from two-year-old tropically adapted bulls were split and fixed and submitted to microscopic sperm morphology assessment, and snap-frozen for sperm nuclear integrity assessments by SPDA and SCSA. For SPDA, the variables were defective (MCB) and deprotaminated (HCB), and for SCSA, the variables were DNA fragmentation index (DFI) and high DNA stainability (HDS). HCB correlated with DFI; τKen = 0.317 and HDS; 0.098, and MCB correlated with DFI; 0.183 (p < 0.001). The percentage of morphological normal spermatozoa was correlated negatively to DFI; τKen = -0.168, MCB; -0.116 and HCB; -0.137 (p < 0.001). HCB and DFI were both positively correlated to head defects, proximal droplets, and spermatogenic immaturity, but not to distal droplets, vacuoles, or diadems. Sperm DNA integrity and protamination, using the SCSA and SPDA, respectively, in bulls show associations with morphological parameters, particularly with head shape abnormalities and indicators of spermatogenic immaturity, including proximal droplets. The vacuoles and diadem defects were not correlated with sperm nuclear integrity, and hence, these are likely physiological features that may not directly affect sperm chromatin configuration.

show abstract

Influence of season of birth on growth and reproductive development of Brahman bulls

Cited by 21 publications

References 22 publications

Relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls

Relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls

Sexual Maturation in the Bull

Morphological defects, sperm DNA integrity, and protamination of bovine spermatozoa

Contact Info

Product

Resources

About