LYCOPENE- AND VITAMIN E-INDUCED MODULATION OF PHYSIOLOGICAL AND REPRODUCTIVE PERFORMANCE INDICES IN LAYING HENS DURING THE DRY SEASON
LYCOPENE- AND VITAMIN E-INDUCED MODULATION OF PHYSIOLOGICAL AND REPRODUCTIVE PERFORMANCE INDICES IN LAYING HENS DURING THE DRY SEASON
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Date
2021-03
Authors
OBIDI, Joseph Ayodele
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Abstract
Environmental stress is progressively becoming a globally significant factor of concern to
animal agriculture due to climate change.Variations in thermal environmental conditions in
the tropical Guinea Savannah, especially when such changes are acute, frequent and abrupt
constitute oxidative stress to animal well-being and productivity. The aim of the present
study was to determine the ameliorative activity of supplemented lycopene (L) and vitamin
E (VE) on thermal stress-induced changes in physiological and performance indices of
laying hens during the harmattan and hot-dry seasons. Four hundred, apparently healthy
laying hens, aged 41 weeks were divided into four groups each (n = 100): group 1 = L+VE,
were coadministered with lycopene (30 mg⁄kg body weight) and vitamin E (250 mg ⁄ kg
body weight); group 2 = L, were supplemented with lycopene only ((30 mg ⁄ kg body
weight)); group 3 = VE were administered with vitamin E only (250 mg ⁄ kg body weight)
and group 4 = CONTROL were not supplemented with any antioxidant. The antioxidants
were administered for 5 weeks each, during the harmattan and hot-dry seasons. During the
study period physiological and performace parameters were recorded daily and weekly. The
results showed that thermal environmental conditions during the harmattan and hot-dry
seasons were stressfull to the laying hens, but the hot-dry condition was more stressful to
the birds. During the harmattan (cold-dry) season, laying birds were exposed to
environmental stress ranging from cold to heat stressor. During the hot-dry season, laying
birds were susceptible to severe heat stress almost all the day. The stressful conditions
resulted in significant impairment in performance parameters of laying hens. A significant
increase in percentage hen-day egg production was recorded in laying hens that were
administered antioxidants, lycopene and vitamin E during the two seasons; however, it was
evident that coadministration of L+VE to hens resulted in the most significant (P < 0.05)
performance parameters. This was followed by laying birds that were administered with
lycopene only and vitamin E only, respectively. Hen-day egg production parameter was
lowest in control laying hens during the two seasons. Oestrogen and progesterone
concentrations were significantly (P < 0.05) higher in antioxidant-administered groups of
laying hens during the two seasons of the study. Results on thyroid function and thyroid
hormone concentrations demonstrated that co-adminstration of lycopene and vitamin E was
most significant on thyroid function during the two seasons, indicating that antioxidants
surported thyroid function which is known to be dysfunctional during thermally-induced
stress condition. Modulatory effect of thyroid hormones activity was more profound during
the harmattan season, increasing cloacal temperatures(CTs) during the early hours of the
day and decreasing CTs during periods commencing from 12:00 h. Modulatotory roles of
antioxidants in the laying hens were in the order: L+VE > L > VE > CONTROL.
Significant (P < 0.05) increase in CTs was recorded in L+ VE and L groups of laying hens
during the study period. Results showed that the effect of VE on CTs was lower than in the
former two groups. There was no significant (P > 0.05) difference in egg weight in
experimental and control groups of laying hens during the seasons. However, internal and
external egg parameters were significantly (P < 0.05) influenced by the supplementation of
antioxidants where L+VE groups of laying hens recorded higher values in eggshell
diameter. The group also showed a significant (P < 0.05) increase in egg albumen and yolk
parameters. During the hot-dry season, ovarian function showed a more resilient aptitude in
egg production. Countable white follicles and growing preovulatory yellow ovarian
follicles were greater (P < 0.05) in number in antioxidant-administered laying hens. There
was no transitional shelled egg in-uterus in any of the laying hens supplemented with
antioxidants; only in control groups were shelled eggs-in-uteri prominent. It is concluded that the harmattan and hot-dry seasons were thermally stressful to laying hens. The
administration of antioxidants lycopene and⁄or vitamin E ameliorated the effects of the
stress and improved the welfare and productivity of the laying hens.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY IN VETERINARY PHYSIOLOGY
DEPARTMENT OF VETERINARY PHYSIOLOGY,
FACULTY OF VETERINARY MEDICINE,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA
Keywords
LYCOPENE- AND VITAMIN E-INDUCED MODULATION,, PHYSIOLOGICAL,, REPRODUCTIVE PERFORMANCE INDICES,, LAYING HENS DURING,, DRY SEASON.