Country：Japan

Country：Japan

Introduction
Studies have been very limited to clarify associations among metabolic status, testicular hormonal secretions and semen characteristics in bulls. The present study was designed to compare plasma insulin-like growth factor-I (IGF-I), insulin-like peptide 3 (INSL3), testosterone and inhibin concentrations around puberty in beef bulls between normal and abnormal semen.

Materials and Methods
Blood samples were obtained monthly from Japanese Black beef bulls (n = 66) from 4 to 24 months of age. Bulls were divided into groups based on their semen parameters; normal (N), abnormal fresh (A) and low fertility after freezing and thawing (L). Abnormal fresh semen was further divided into malformation only (M) and malformation plus low motility (M+L). Plasma IGF-I, INSL3, testosterone and inhibin concentrations were measured by either EIA or TRFIA.

Results and Discussion
Plasma IGF-I concentrations were lower (P < 0.05) in L group than N group at 8-9, 11, 15-21 months. Plasma INSL3 concentrations were lower (P < 0.001) in M+L group than N group at 6-22 months. Plasma testosterone concentrations did not differ among N, A and L groups. Plasma inhibin concentrations were lower (P < 0.05) in A and L groups than N group at 8-13, 16, 19-20 and 10-12, 16-21 months, respectively. These results suggest that lower plasma IGF-I concentrations in bulls may be associated with low fertility of frozen semen. Lower INSL3 concentrations are a likely cause for sperm malformation plus low motility while reduced inhibin secretion can be 　responsible for both of fresh semen abnormality and low fertility.

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

DOI： 10.1002/rmb2.12485

PubMed

Other URL： https://onlinelibrary.wiley.com/doi/10.1002/rmb2.12485

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

<p> Insulin-like peptide 3 (INSL3) and sex steroids were measured in bovine dominant follicles and corpora lutea during the estrus cycle and in follicular cysts. Paired ovaries from beef heifers (n = 47) were classified, by their morphological features, either into four stages of the estrus cycle (Day 1 = day of ovulation, Day 20 = day of estrus) as Stage I (Days 1–4; n = 8), Stage II (Days 5–10; n = 10), Stage III (Days 11–17; n = 8), and Stage IV (Days 18–20; n = 11) or follicular cystic (n = 10). Cysts (n = 15) were subdivided into estrogen-active (n = 7) and estrogen-inactive (n = 8) cysts. INSL3, testosterone, and estradiol-17β concentrations in the dominant follicular fluid of Stage IV were higher than those in Stages II and III (P < 0.05). INSL3 concentrations in the cystic fluid were similar to those in dominant follicles at Stage IV, whereas testosterone and estradiol-17β concentrations were lower in cysts (P < 0.05). INSL3 content per estrogen-inactive cyst was higher than that of Stage IV (P < 0.05). INSL3 and progesterone concentrations in luteal tissue and contents per corpus luteum were higher in Stages II and III (P < 0.05). In conclusion, INSL3 secretion in bovine dominant follicles increased with maturation. Follicular cysts may retain the production of INSL3 during their formation but tend to lose the capacity for testosterone secretion. Estrogen-inactive cysts subjected to advanced atresia may accumulate more INSL3. INSL3 production in bovine corpora lutea is enhanced during maturation.</p>

DOI： 10.1262/jrd.2022-018

PubMed

Other URL： https://www.jstage.jst.go.jp/article/jrd/68/5/68_2022-018/_article/-char/en

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1016/j.theriogenology.2020.02.035

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： https://doi.org/10.1262/jrd.2020-035

Other URL： https://www.jstage.jst.go.jp/article/jrd/66/6/66_2020-035/_article/-char/en

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.1292/jvms.18-0151

Other URL： https://www.jstage.jst.go.jp/article/jvms/80/12/80_18-0151/_article

Total pages：567   Responsible for pages：230-236   Book type：Textbook, survey, introduction

Total pages：312   Responsible for pages：241-257   Book type：Textbook, survey, introduction

Responsible for pages：215-221   Book type：Textbook, survey, introduction

Responsible for pages：219-238   Book type：Textbook, survey, introduction

黒毛和種子牛の発育・栄養状態と生殖機能の発達との関連性解析