ABSTRACT
Aim of this study was to assess the effects of graded levels of dietary protein on scrotal circumference,liveweight changes, semen characteristics, gonadal and extragonadal sperm reserves and serum testosterone profile in Yankasa rams. Fifteen rams were used in this study aged 19.06 ± 2.4 months and weighing 19.4 ±1.6 kg with body condition scores of 3.5. They were divided into three treatment groups (A, B and C) based on dietary protein level. Groups A, B and C received 10%, 15% and 20% crude protein respectively. The rams were managed under intensive system, kept in separate pens, fed individually and allowed two weeks adjustment period. All rams were fed a basal diet of hay (Digitariaspp) ad-libitum and given a supplement ration of concentrate mixture at 2% body weight/day. Body weights and scrotal circumference were recorded weekly. Semen samples were collected weekly for analyses using battery controlled electro ejaculator. Three rams from each group were sacrificed for determination of gonadal and extragonadal sperm reserves. The overall mean scrotal circumferences obtained through the study period for the groups revealed significant (P < 0.05) difference in the increase between group A and B with values of 22.9 ± 0.6 cm and 26.2 ± 0.7 cm. There was also a significant (P < 0.05) increase between group A and C (22.9 ± 0.60 cm and 26.8 ± 0.8 cm) respectively. Rams fed 10% crude protein had significantly (P < 0.05) lower mean live weights (18.8 ± 0.4kg) than those fed 15% (22.1 ± 0.6kg) and 20% (24.1 ± 0.1kg) crude protein. Mean Packed cell volumes obtained in this study revealed rams fed 15% crude protein had significantly (P < 0.05) higher values (31.3 ± 0.9%) than those fed 10% (25.9± 0.7%) and 20% (25.9 ± 0.7%) crude protein. There were no significant (P > 0.05) difference in mean white blood cells counts between all groups. Rams fed 10% had the lowest value of 8.4 ± 0.3 x106/µl as compared to other groups (8.4 ± 0.2 x106/µl and 8.4 ± 0.2 x106/µl). Rams fed 15% crude protein had significantly (P< 0.05) higher RBC values (5.2 ± 0.11 X106 µl) than other groups (4.2 ± 0.1 X106 µl and 5.1 ± 0.01 X106 µl). Semen concentration was significantly (P < 0.05) higher in rams fed 15% crude protein (163.1 ± 20.6 x106/ml) than group A (96.4 ± 16.3 x106/ml) and group C (98.8 ± 8.5 x106/ml). Motility patterns recorded revealed rams fed 15% crude protein had significantly (P < 0.05) higher values (75.1 ± 3.0%) than group A (54.7 ± 3.8%), and group C (53.9 ± 3.9%). There was no significant difference in reaction time, but rams fed 15% crude protein had the lowest reaction time. Regardless of crude protein levels, left testes weighed more than the right testes. Testicular weights and gonadal reserves were highest in rams fed 20%, but the difference with other groups were not statistically (P > 0.05) different. Regardless of crude protein intake, the corpus epididymis had the lowest reserves, while the cauda had the highest reserves. Rams fed 20% crude protein had the highest abnormalities when compared with those fed 10% and 15% crude protein. This difference was however not statistically (P > 0.05) different. Feeding rams 15 % C.P gave significantly higher values in terms of body weight, scrotal circumference, semen concentration, sperm motility and percentage live sperm, than in rams fed 10 % C.P. From this study,Yankasa rams should be fed crude protein levels of 15% for better reproductive performance. However, studies should also be conducted to investigate if antioxidants could ameliorate some of the effects of low and high levels of protein diets that were observed in this study.
CHAPTER ONE
INTRODUCTION
1.1 Background of the study
Chronic low animal protein intake in developing countries is a basic problem that needs an urgent solution (Attahet al., 2006). The low animal protein intake may be attributed to low livestock productivity and therefore available animal protein are very expensive for the growing population with a very low per capita income. Successful reproduction as an important factor in livestock production economy depends on genetic merit, physical environment, nutrition and management (Rasbech, 1984). In Nigeria, a major limitation to animal production is poor reproductive performance (RIMS, 1992). Other factors are skyrocketing prices and scarcity of conventional animal feed rich in protein. Enjalbert (2006) attributed many reproductive health disorders in animals to diet inadequacy. It is well documented that protein deficient feeds reduce semen quality and sexual activity in bulls (Brown, 1994). The relationship between nutrition and reproduction is an increasingly important topic and the interactions have important implications for the reproductive performance of farm animals (Bindariet al., 2013). The major reason for low levels of animal production in numerous African countries is the inadequate supply and low level of feeding due to serious shortage of feedstuffs (Amata, 2014). Nutrition plays a major role in enhancing reproductive efficiency in all animals (Bindariet al., 2013). The effects of nutrition particularly underfeeding and flush-feeding on female fertility have been documented (Lozano et al., 2003). The reproductive ability in the male comprises the production of semen containing normal spermatozoa in adequate concentration, together with the desire and ability to mate (Oyeyemi and Ubiogoro, 2005). Several studies have documented the interrelationship between energy intake and reproductive performance in adult rams (Murray et al., 1990) and there is no doubt that protein deficient feeding can reduce semen quality and sexual activity (Okolskiet al., 1971; Brown, 1994). Carbohydrate, protein and nucleic acid metabolism and their deficiency may impair spermatogenesis and libido in males, embryonic development and survival, post-partum recovery activities, milk production, offspring development and their survival in females (Smith and Akinbamijo, 2000; Alejandro et al., 2002; and Mitchell et al., 2003). Nutrition is a major factor in the effectiveness of reproductive function. It may affect the efficiency of related hormone production and the growth of reproductive organs. Studies have demonstrated that luteinizing hormone (LH) secretion during early gonadotropin rise is elevated and can be sustained for a longer period when calves are fed with improved nutrition during calfhood (Cheah and Yang, 2011). The efficiency of sperm production, libido and quality of spermatozoa tend to remain uniform throughout the reproductive life of an animal but may be significantly altered by age, nutrition, environment, health status, drugs and chemicals (Togun and Egbunike, 2006). Under-nutrition poses adverse effect on the reproductive capacity of males, therefore successful reproduction requires complete provisions of macro and micro-nutrients (Zambrano, 2005; Abdu, 2008). Nutrition may affect the efficiency of related hormone production and the growth of reproductive organs (Almeida et al., 2007). The fertility of males and females in a particular herd/flock, as well as level of nutrition to a large extent, determines the rate of production in any livestock industry (Abdulrashid and Darren, 2016). Restricted diets significantly decrease the number of cells of the spermatogenic series at all stages and the number of sertoli cells. Thus, it is apparent that the cellularity of the tubular epithelium is significantly lower in low nutrition animals compared to those of high nutrition (Almeida et al., 2007). Nutritional deficiency is usually caused by general underfeeding with rations of poor quality (Rekwotet al., 1988). These effects on reproduction are usually directed at the level of anterior pituitary gland, which fails to secrete enough gonadotropins to stimulate the testis to produce testosterone and semen (Asdell, 1955).
1.2 Statement of research problem
In Nigeria, consumption of animal protein is still low, as such improving the level of protein intake in most tropical countries is important, given the fact that daily protein intake has been shown to be below standard requirements in most developing countries. Meat supply plays a significant role in addressing problems of macro and micro nutrients deficiency in diets of many parts of the world, particularly among the urban areas of developing countries (Boland et al., 2013). Reproductive well-being and performance of farm animals is largely dependent on their nutritional status (Fernandez et al., 2004). Protein deficient rats have a reduced hypothalamic content of GnRH and reduced serum concentrations of LH, FSH, and testosterone (Glass et al., 1979). Low protein intakes result in decreased sperm production or output in bulls (Rekwotet al., 1988) and rats (Vawda and Mandlwana, 1990). There is need for increased livestock production to meet the growing demand for animal protein.
1.3 Justification for the study
Previous study conducted by Jibrilet al. (2011) investigated effects of protein diets on reproductive performance using Dried Layer Litter as source of protein in Yankasa rams, which is an unconventional source of protein. Studies are scarce on effects of dietary protein on reproductive performance using conventional feed source, hence this study investigated the effects of graded levels of dietary protein of Yankasa rams on liveweight changes, spermiogram and gonadal sperm reserves.
1.4 Aim of the study
The aim of this study was to assess the effects of graded levels of dietary protein using cotton seedand palm kernel cakes on haematological parameters, live-weight changes, semen characteristics, gonadal and extragonadal sperm, spermatid reserves and serum testosterone profiles in Yankasa rams.
1.5 Objectives of the study
The specific objectives of the study are to determine the:
- Effect of graded levels of protein diets (cotton seed and palm kernel cakes) on Live-weight changes in Yankasa rams.
- Effect of graded levels of protein diets (cotton seed and palm kernel cakes) on scrotal circumference in Yankasa rams
- Effect of graded levels of protein diets (cotton seed and palm kernel cakes) of
- Effect of graded levels of protein diets (cotton seed and palm kernel cakes) on Semen characteristics (spermiogram) in Yankasa rams.
- Effect of graded levels of protein diets (cotton seed and palm kernel cakes) on Gonadal and extragonadal sperm and spermatid reserves in Yankasa rams.
1.6 Research Questions
- What are the effects of graded levels of dietary protein (cotton seed and palm kernel cakes) onliveweight changes in Yankasa rams?
- What are the effects of graded levels of dietary protein (cotton seed and palm kernel cakes) on scrotal circumference in Yankasa rams?What are the effects of graded levels of dietary protein (cotton seed and palm kernel cakes) onhaematological parameters in Yankasa rams?
- What are the effects of graded levels of dietary protein (cotton seed and palm kernel cakes) on semen characteristics (spermiogram) in Yankasa rams?
What are the effects of graded levels of dietary protein (cotton seed and palm kernel cakes) gonadal and extragonadal sperm and spermatid reserves in Yankasa rams?
