Assessment of semen quality parameters of three Tanzanian native chickens
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Date
2022
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Sokoine University of Agriculture
Abstract
Tanzania has a total chicken population of approximately 92.8 million, of which about
42.7 million are native breeds (Gallus gallus domesticus) and 50.1 million are exotic
breeds kept primarily for commercial purposes. The poultry industry plays an important
role in terms of food security, source of income, and meeting economic and social
obligations for the household, especially for poor families. Despite their importance,
research on improving productivity of the native chicken’s strains is lacking. Therefore,
the present study assessed semen quality parameters of freshly collected semen of
three different native chicken ecotypes; Ching’wekwe, Kuchi and Morogoro-medium
and also investigated the effect of synthetic Gonadotropin releasing hormone (GnRH)
on semen quality parameters of Tanzanian native chickens. For assessment of semen
quality, twelve roosters (four from each ecotype) with two age groups (11-15 and 24-28
months) were used as semen donors and a total of 192 semen samples were collected
from 12 roosters (four from each ecotype) using the abdominal massage technique at
weekly interval for four consecutive months. Evaluation of the effect of GnRH treatment
on semen quality parameters in three ecotypes of Tanzanian native chickens was
performed; where a total of thirty-six mature cockerels from Tanzanian native chicken
ecotypes were used. Thirty cockerels (ten from each ecotype) were intramuscularly
injected with 0.2 ml of GnRH (Factrel®) once in a week for five consecutive weeks while
six (two from each ecotype) were used as a control group only receiving normal saline
solution. Semen was collected at weekly interval by abdominal massage technique
starting immediately after last GnRH injection for five consecutive weeks. Semen
characteristics of individual samples were evaluated. For assessment of semen
parameters, volume, pH, sperm motility, sperm concentration, proportion of
spermatozoa with normal morphology and proportion of live spermatozoa among the
ecotypes varied from 0.42±0.04 to 0.52±0.03mL, 7.01±0.00 to 7.02±0.00, 72.81±1.27 to
76.63±1.35%, 3.90±0.98 to 4.12±1.96 x 10 9 /mL, 86.16±0.55 to 89.38±0.80% and
88.06±1.13 to 90.97±0.81% respectively. However, only the variations in proportion of
spermatozoa with normal morphology and proportion of live spermatozoa among the
ecotypes were significant (P<0.05). The semen volume, pH, sperm motility, sperm
concentration, proportion of spermatozoa with normal morphology and proportion of live
spermatozoa among the two age groups varied from 0.44±0.03 to 0.52±0.03mL,
7.01±0.00 to 7.02±0.00, 73.88±1.13 to75.92±0.99%, 3.80±0.45 to 4.28±0.32 x 10 9 /mL,
87.02±0.58 to 88.15±0.64%, 88.27±0.77 to 89.83±0.77% respectively. Nevertheless,
only the variations in semen volume among the two age groups were significant
(P<0.05). The Pearson correlation coefficients between semen volume and other
semen quality characteristics were mostly low to medium with positive values ranging
from 0.01-0.51 between semen volume and sperm motility and between morphological
normal spermatozoa and proportion of live spermatozoa, respectively. Regarding the
effect of GnRH on semen quality, semen parameters increased significantly (p<0.05)
between control and treatment groups; including semen volume (0.48±0.02 mL versus
0.55±0.02 mL), sperm motility (74.90±0.76% against 80.02±0.30%), concentration
(4.04±0.18 × 10 9 /mL versus 4.80±0.14 × 10 9 /mL), proportion of morphological normal
spermatozoa (87.58±0.43% versus 91.25±0.3%) and proportion of live spermatozoa
(89.05±0.55% against 91.65±0.31%) but semen pH did not change between control and
treatment groups. It can be concluded that although there is minimal variation in semen
quality among ecotypes and age groups, all the ecotypes might still be used in breeding
purposes to maintain native chickens and semen quality parameters can be improved
by injecting GnRH to cockerels and therefore increasing productivity in the poultry
industry.
Description
Dissertation
Keywords
Semen quality, Chickens, Tanzania, Local chicken