Testicular Development, Daily Sperm Production and Epididymal Sperm Reserves in 15-mo-old Angus and Hereford Bulls: Effects of Bull Strain Plus Dietary Energy

Abstract

Bull calves (n = 143) were obtained from two strains of Angus and two strains of Hereford cattle for which replacements were selected on the basis of superior feedlot growth performance on either high- or medium-energy diets. From weaning to slaughter at 15 mo of age, bulls were fed either the high-energy (80% grain + 20% forage) or medium-energy diet (100% forage) corresponding to their strain. Bulls in high-energy diet groups had a greater (P less than .05) scrotal circumference at 12 mo, but not 15 mo of age, than bulls in medium-energy diet groups. Compared with Hereford bulls, Angus had greater (P less than .01) scrotal circumference (36.1 vs 33.9 cm) and greater (P less than .05) paired testes weight (570 vs 464 g) at 15 mo of age. Daily sperm production per gram testicular parenchyma (DSP/g) was affected by strain-diet (P less than .01) but not by breed. Bulls in medium-energy diet groups had 12% greater DSP/g than did high-energy diet bulls (17.4 X 10(6) vs 15.5 X 10(6)). Daily sperm production (DSP) was 9% and 30% greater (P less than .01) for medium-energy diet bulls in 1980 (8.2 X 10(9) vs 7.5 X 10(9)) and 1981 (8.0 X 10(9) vs 6.2 X 10(9)), respectively, compared with high-energy diet bulls. The effect (P less than .01) of breed on DSP was attributed to breed differences in paired testes weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactions between nutrition and reproduction in the management of the mature male ruminant

“…For example, in the experiment by Van Demark and colleagues, the 'low' plane of nutrition had little effect on body weight, as well as testicular size, even over 12 months, although production of spermatozoa was reduced . In the other cases, the 'high' planes seemed to constitute overfeeding, as the sperm production was markedly decreased compared to 'medium' or 'low' planes (Coulter et al, 1987;Mwansa and Makarechian, 1991). In addition, the energy and protein balance of the experimental diets requires clarification, as both have been manipulated in these studies, but not compared in the one experiment.…”

“…As mentioned above, the Kastelic laboratory has added an extra level of sophistication to our understanding of the effects of nutrition over the first 18 months of life (review: Barth et al, 2008). However, after the period of rapid growth has ended, there appears to be little or no response to nutrition (Flipse and Almquist, 1961;Coulter et al, 1987). Caution is needed with these older studies on mature bulls.…”

Fertility of yearling beef bulls during mating

“…Young bulls attaining satisfactory-classification on a prebreeding BSE would therefore presumptively be expected to advance in physical and reproductive capability. However, environmental and physiological stressors are known to unfavorably influence some physical and seminal characteristics [17][18][19][20][21]. Factors such as season, climatic temperatures, toxic principles, disease and injury, physiologic stress and nutritional imbalances have been linked with alterations in scrotal circumference and seminal quality [17,22].…”

Factors Affecting Body Weight, Scrotal Circumference Hip Height and their Relationships with Birth Weighl Preweaning and Postweaning Gains in Young Bulls

“…Bailey et al (1991) reported no significant sire by diet interaction for growth rate and feed efficiency. However, Coulter et al (1987) reported a diet x breed interaction (PC0.05) for body weight at 12 and 15 months of age in Angus and Hereford bulls fed either a high or medium energy diets.…”