ABSTRACT
Effect of frequency of ejaculation on semen characteristics of heavy ecotype chicken raised in the derived savannah region of Nigeria was studied using twelve heavy ecotype cocks. The cocks were randomly assigned to three treatments with four cocks in each treatment. Ejaculation frequencies once, twice and thrice per week, with T1 representing once, T2, twice and T3, thrice were imposed on the birds. The experiment lasted for a period of eight weeks with a two-week pre-experimental period during which cocks were trained for semen collection and six weeks of semen collection schedule. Feed and water were supplied ad libitum during the experiment. Semen collected were analysed for volume, progressive sperm motility, percentage live and dead spermatozoa, percentage normal and abnormal sperm cells, sperm concentration and total sperm in the ejaculate. Result showed that ejaculate volume and total sperm in the ejaculate were not significantly (p>0.05) affected by the ejaculation frequencies while progressive sperm motility, percentage live and dead sperm cells, percentage normal and abnormal sperm cells and sperm concentration were all significantly (p<0.01) affected by the ejaculation frequencies. Cocks ejaculated twice weekly recorded the highest value sperm in motility 77.70 ± 0.99% , live 76.04 ± 0.90% and normal spermatozoa, 77.29 ± 0.85% while cocks ejaculated thrice weekly recorded the lowest values of 65.96 ± 1.87%, 66.38 ± 1.90%, 68.40 ± 1.92% for motility, live and normal spermatozoa respectively. Also the cocks ejaculated thrice recorded the highest value for dead (33.44 ± 1.90%) and abnormal spermatozoa (31.59 ± 1.92%) while cocks ejaculated twice recorded the lowest values of 23.95 ± 0.90%, 22.70 ± 0.85% for dead and abnormal spermatozoa, respectively. It was concluded that twice weekly ejaculation gave better semen quality. Therefore, it is recommended that twice per week ejaculating frequency should be used for cocks for optimum semen quality and for high semen output.
1.0 Background of the study
CHAPTER ONE
INTRODUCTION
Rapid human population growth and low protein intake are some of the major problems facing developing countries like Nigeria. Poultry production is one of the surest and fastest means of bridging the animal protein supply needs of any nation, especially for countries like Nigeria where it has been reported that an average individual consumes about 7.5g of animal protein as against 28g consumed by an average Briton (Mmereole et al., 2001).
The local chickens constitute the majority of poultry types in Nigeria, being about 106 million in population (Ajayi, 2010) with more than 80% in the rural areas where they contribute substantially to annual meat and egg production. There are various ecotypes of local chicken in the different agro ecological zones of the country and they vary in shape, size and plumage colours (Oluyemi et al., 1982). The different ecotypes can be grouped into two major categories on the basis of body size and body weight as ‘light’ ecotype and ‘heavy’ ecotype (Momoh and Nwosu, 2008). Light ecotype refers to those types belonging to the swamp, rainforest and derived savannah agro-ecological zones whose mature body weights range between 0.68-1.5kg. The heavy ecotype represents the types from the dry savannah (Guinea and Sahel savannah), montane regions and cattle kraals of the north, whose mature body weights range from 0.9-2.5kg (Atteh, 1990).
The importance of semen evaluation in poultry breeding (natural and artificial breeding), for selecting breeding males or for routine monitoring of their reproductive performance cannot be over emphasized. Semen of breeding cocks is usually evaluated to ascertain the quality before it is employed for breeding programmes.
The assessment of semen quality characteristics of Nigeria local chicken gives excellent indices of its reproductive potential (Zahradden et al., 2005) and has been reported to be a major determinant of fertility and subsequent hatchability of eggs (Peters et al., 2004). For efficient breeding programme, artificial insemination (AI) is preferred to natural mating. One of the advantages of AI over natural mating is the efficient use of male (Koophar et al., 2010). Successful application of artificial insemination to commercial hatchery operations depends on the quantity and quality of sperm obtained from breeder males (Zhaug, 2006). Higher semen output in terms of semen volume and sperm concentration determines the number of females that can be inseminated with it. While increased semen output can be achieved from breeder male through more frequent ejaculations (Fan et al., 2004; Klimowicz et al., 2005, Zhaug 2006), evidence exists that some semen quality parameters decrease progressively with increase in the frequency of ejaculation (Nwachukwu et al., 2006; Onukwufor and Ezekwe 2006). Most of the research findings on the local chickens of Nigeria (Nwosu, 1979) were obtained from research work on the chicken types described as light ecotype found in the southern part of the country. The chicken type from savannah, montane regions and cattle kraals of the north described as heavy ecotype have not been so much evaluated. Therefore, this study was aimed at evaluating the effect of frequency of ejaculation on semen characteristics of heavy ecotype chicken raised in Derived Savannah region of Nigeria.
1.1 Objective
The broad objective of this study was to evaluate the effect of frequency of ejaculation on semen characteristics of heavy ecotype raised in Nsukka, Enugu state.
Specific objectives were to evaluate the effect of ejaculation frequencies on:
i. Semen Colour ii. Semen Volume iii. Semen Motility
iv. Live and dead spermatozoa
v. Normal and abnormal spermatozoa and vi. Sperm concentration
1.3 Justification
High semen output is achieved through frequent ejaculation and the volume and concentration determine the number of females to be inseminated. Semen needs to be evaluated so as to ascertain its quality for use in artificial insemination (AI). Artificial insemination is one of the most effective and widely used techniques for the genetic improvement of farm animals. It is employed on breeder farms to maintain the maximum use of males, as well as to ensure disease prevention, high fertility rates and for economic reason. To obtain the maximum number of spermatozoa and maintain high rates of sperm production, the semen needs to be collected at a frequency that maintains output over time. Therefore, the result of this study will help in determining the frequency that gives better semen quality for use in the genetic improvement programme of local chicken ecotypes in Nigeria.
This material content is developed to serve as a GUIDE for students to conduct academic research
EFFECT OF FREQUENCY OF EJACULATION ON SEMEN CHARACTERISTICS OF HEAVY ECOTYPE CHICKEN RAISED IN DERIVED SAVANNAH REGION OF NIGERIA
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