MSc

A study was conducted to assess the combined effect of heat stress and
nutritional restriction on growth and reproductive performances in Osmanabadi
Bucks. Twenty four adult Osmanabadi bucks (average body weight (BW) 16.0
kg) were used in the present study. The bucks were divided into four groups viz.,
C (n=6; control), HS (n=6; heat stress), NS (n=6; nutritional stress) and CS (n=6;
combined stress). The study was conducted for a period of 45 days. C and HS
bucks had ad libitum access to their feed while NS and CS bucks were under
restricted feed (30% intake of C bucks) to induce nutritional stress. The HS and
CS bucks were exposed to solar radiation for six hours a day between 10:00 h to
16:00 h to induce heat stress. The data was analyzed using repeated measures
analysis of variance. Both C and HS groups showed significantly higher (P<0.01)
body weight and body condition scoring (BCS) as compared to restricted feeding
groups (NS and CS). The allometric measurements also were significantly (P <
0.01) lower in restricted fed groups (NS and CS) as compared to ad libitum fed
groups in CS bucks as compared to other groups (C and HS). Among the scrotal
measurements, Scrotal circumference afternoon (SCA) and scrotal length
afternoon (SLA) differed significantly (P<0.05) between the groups. The highest
semen volume (P<0.01) was recorded in C group bucks as compared to other
groups. The significantly (P<0.05) higher mass motility and progressive motility
was recorded in C group bucks. However, both mass motility and progressive
motility did not differ between the stress groups (HS, NS and CS). The highest
plasma GH (P<0.01) was recorded in CS group and the lowest in rest all the
groups (C, HS and NS). The highest plasma testosterone level was recorded in C
group and the lowest in rest all groups (HS, NS and CS). The interaction between
treatment and experimental days significantly (P<0.01) influenced body weight,
BCS, allometric measurements, scrotal circumference, left testicular length and
width, right testicular width, semen volume and growth hormone concentration.
The higher expression of testicular Heat Shock Protein 70 (HSP70) Messenger
Ribonucleic Acid(mRNA) was reported in HS goats. Testicular section showed
significant changes for different stresses. The highest loss of spermatid density
indicating decreased spermatogenesis was recorded in CS followed by HS and NS
109groups compared to C group. It can be concluded from this study that when
nutrition is not compromised Osmanabadi bucks were able to withstand heat
stress. This is evident from the non-significant difference on various growth and
reproductive parameters studied between C and HS groups. Further, the study also
revealed that Osmanabadi bucks possessed superior adaptive capability to
combined stresses simultaneously. This is evident from the significant interaction
of treatment and experimental days on majority of the parameters studied.