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This study aimed to investigate the effects of insulin resistance (IR) during the close-up dry period on the metabolic status and performance of dairy cows as well as to determine the effects on body weight (BW) and metabolic status of their calves. An insulin tolerance test (ITT) was conducted by administering 0.05 IU/kg BW of insulin to 34 multiparous Holstein cows at 3 weeks prepartum. Blood samples were collected at 0, 30, 45 and 60 min after insulin injection, and cows were divided into two groups based on the time required for glucose to reach the minimum levels [non-IR (NIR), 45 min (n=28); and IR, 60 min (n=6)]. Blood or milk sampling and body condition score (BCS) estimation were performed twice weekly during the experimental period. Blood samples from calves were collected immediately after birth. Cows with IR showed lower BCS (P<0.05) and serum urea nitrogen (P<0.05) and glucose concentration (P=0.05) before calving, and lower serum non-esterified fatty acid concentration (P<0.05) and milk yield (P<0.05) and earlier resumption of luteal activity (P<0.05) after calving; their calves showed lower BW (P<0.05) and plasma insulin-like growth factor-I concentration (P<0.001) and higher plasma insulin concentration (P<0.05). In conclusion, IR at 3 weeks prepartum in dairy cows is related to postpartum metabolic status and performance along with growth and metabolic status of their calves.

Adult male brown bears (Ursus arctos Linnaeus, 1758) display tree-marking behavior to chemically signal their dominance throughout the nondenning period, and this behavior peaks during the breeding season. Within the scent-marking sequence, back rub is a core marking posture. The present study investigated (i) seasonal changes in sebaceous glands in the back skin of brown bears and (ii) the relationship between those changes and testosterone levels. Back skin tissue samples and blood were collected from captive adult intact and castrated males during prebreeding, transitional, breeding, and postbreeding seasons, which were concurrent with back skin observations. In intact males, during the transitional and breeding seasons, an oily secretion from the back skin was observed along with enlarged sebaceous glands. The plasma testosterone concentrations during the transitional and breeding seasons were increased compared with the pre- and post-breeding seasons. Secretions and enlarged sebaceous glands were not found in castrated males, and the plasma testosterone concentrations remained at baseline levels. Oily secretions of the back skin glands that appear more abundant during the breeding season are rubbed against trees. Changes in size and volume of sebaceous glands, and thus their secreting capacity, are likely testosterone-regulated.

In this study, we examined the effect of the locations of the first-wave dominant follicle (DF) and corpus luteum (CL) on fertility. In total, 350 artificial insemination (AI) procedures were conducted (lactating dairy cows: n = 238, dairy heifers: n = 112). Ovulation was confirmed 24 h after AI. The locations of the first-wave DF and CL were examined 5 to 9 d after AT using rectal palpation or transrectal ultrasonography. Lactating dairy cows and dairy heifers were divided into 2 groups: (1) the ipsilateral group (IG), in which the DF was ipsilateral to the CL; and (2) the contralateral group (CG), in which the DF was contralateral to the CL. Pregnancy was diagnosed using transrectal ultrasonography 40 d after AI. Conception rates were 54.0% in all cattle: 48.9% in lactating dairy cows, and 58.9% in dairy heifers. The incidence of the first-wave DF location did not differ between IG and CC (all cattle: 184 vs. 166; lactating cows: 129 vs. 109; heifers: 55 vs. 57 for IC vs. CG). Conception rates were lower in IG than in CG (all cattle: 40.2 vs. 69.3%; lactating dairy cows: 38.0 vs. 67.0%; dairy heifers: 45.5 vs. 73.7%, for IC vs. CG). Conception rate was not affected by season or live weight in heifers and lactating cows. In addition, days in milk at AI, milk production, body condition score, and parity did not affect conception in lactating cows. In summary, development of the first-wave DF in the ovary ipsilateral to the CL was associated with reduced conception rates in both lactating cows and heifers.