Review of Literature

Chapter-II Review of Literature Environmental factors such as changes in light durations, rise and fall in temperatures, changes in relative humidity during an annual cycle, modulate the immune system. The brighter light intensity could improve health status and provide opportunities for normal behaviour rhythms (Blatchford et.al., 2009). The birds respond to change in day-length for adaptation to seasonal variation in the climate. The seasonal fluctuation in temperature and light duration lead to changes in hormone levels, which are needed in modulation of metabolic activities that ultimately lead to proper maintenance for a physiological adjustment particular season. Quails in the wild are migratory in nature. They are ground loving birds and hide themselves under the bush or in nests prepared in hollow of the

9 ground covered with leaves or grass. They are usually monogamous, polygamy is an exception. They thrive on seeds of various grasses, grains and insects or their larvae. Coturnix are widely distributed in Europe, Africa and Asia where they are regarded as migratory species. Records of their existence date to the ancient civilisation of these continents (Cawley W.O. & Cain J.R., 1914). They were first raised as pets and singing birds, but by 1900 quails in Japan had become widely used for meat and egg production. The Government of India has permitted farming of the domesticated quails and consumption of protein by products to the under nourished millions of people of the country (Unni A. 2001). Quails are affected by common poultry diseases but are fairly disease resistant. Japanese quail mature in about 6 weeks and are usually in full egg production by 50 days of age. Life expectancy is only 2 to 2½ years. Females are characterised by light tan feathers with black speckling on the throat and upper breast. The males have rusty brown throat and breast feathers. Adult male quail weigh about 100-140g while the females are slightly heaviour, weighing from 120-160g. (Maurice Randall & Gerry Bolla, 2008). The incubation period for quail is 17-18 days, depending on the strain and incubation procedures. Photoperiod It is widely documented that the timing of reproduction is controlled by external signals such as changes in day length or photoperiod, chemosensory cues from species, food availability and temperature. From a study done by Moore and Siopes (2000), it was clear that quail placed in daily light dark

10 cycles (LD) possessing a diurnal rhythm of melatonin, had significantly elevated immune responses when compared to those birds in constant light (LL). Boon, Visser and Daan, 2000, suggested that long photoperiods stimulate sexual maturation whereas short photoperiods inhibit or delay sexual maturation. Boon et.al., (2000) clearly demonstrated that longer photoperiods are related to both higher energy intake and energy expenditure level, resulting in increased weight gain. Photoperiod is known to affect rates of weight gain in juveniles (Schanbachar BD and Crouse JD, 1981; Wade GN and Bartness, 1984; Negus et.al., 1986., Spears N and Clarke JR, 1986; Larkin et.al., 1991; Prabhakaran et.al., 1991., Nagy TR and Negus NC, 1993; Boon et.al., 1997). In quail, sexual development is known to depend on the length of the daily light period: long photoperiods stimulate sexual maturation, while short photoperiods inhibit or delay sexual maturation (Chaturvedi & Bhatt, 1993; Mills et.al., 1997; Boon et.al., 2000). Sexual maturity in quail can be delayed by the use of a step down light regimen (declining photoperiod) during the growing period of pullets (Keshavarz, 1998).The pineal organ, which is a component of circadian system is influences by the light/dark cycle and it is involved in the control of circadian and circannual rhythms in vertebrates (Reiter R.J. 1993 and Hofman M.A., 2004) The pineal melatonin controls reproduction of photoperiodic mammals and is an integral part of the circadian rhythm in birds (Binkley, 1998). Photoperiod is a powerful environmental agent capable of influencing the physiology of organisms and as such, the usage of diverse artificial photoperiodic schedules for rearing and productivity

11 has become a common poultry practice (Lowry, et.al., 1951; Andrews et.al., 1990; Lewis et.al., 1992; Lewis et.al. 1996). Photoperiod alters morphological characteristics of both GnRH neurons and glia that surround GnRH-neuron axon terminalis in japanese quail (Yamamura et.al., 2004). In adult male pigeons (Columba livia) subjected to prolonged (nocturnal) fasting periods decreased both energy expenditure and body temperature during the dark phase to a larger extent compared to pigeons in and ad lib conditions. (Rashotte et.al., 1995). This resulted in overall lower 24hr energy expenditure. In the works of Charles et.al. (1992), photoperiod can also influence weight gain via an effect on the balance between food intake and digestion. Throughout the light period food intake occurs whereas during the dark period when both food intake and activity are suppressed, digestion can take place. On the other hand, long photoperiods stimulate sexual maturation in both quail and the other bird species (Stein and Bacon 1976; Dunn and Sharp 1990; Siopes and Pyrzak 1990; Prabhakaran et.al., 1991; Classen et.al., 1994; King et.al., 1997; Wingfield et.al., 1997) which also may effect weight gain positively. Nutrient Requirements of Japanese Quail The nutrient requirement of Japanese quail have been studied extensively in the Department of Zoology, Natural University of Singapore and a review of paper of nutrition of Japanese quail has been published by Shim and Vohra (1984). The nutrients that comprise a quail diet are water, protein, carbohydrate, fat, minerals and vitamins. However, the exact dietary

12 requirement of Coturnix are still a subject to debate a standard ration may not be available commercially (Cawley and Cain, 1914). According to Maurice Randall and Gerry Bolla, 2008, a good quality commercial starter ration for game birds or turkeys contains about 25%- 28% crude protein. If this is not available, a chicken starter ration (20% - 22%) protein can also be used, but the birds will grow more slowly. Earlier investigators raised their quail flocks successfully on turkey starter diet containing about 25-28% crude protein (Wilson et.al., 1959, Woodard et.al., 1973; NAS, 1969). Lee et.al., (1977 a and b) have shown that a dietary crude protein level of 24% is needed in starter diet for quail and the protein content may be reduced to 20% by 3 rd week of age. Murakami et.al., 1993a suggested four crude protein levels (20, 22, 24 and 26%) and were evaluated for Japanese quails and it was concluded that after lysine and methionine +cysteine requirements were met 20% crude protein level resulted in best performance from 1 to 42 days of age. During the laying period, Murakami et.al., (1993b) recommended 18% of crude protein, which is lower than the level of 22.42% recommended by Pinto et.al. (1998) whereas levels of 24% and 20% of crude protein are recommended by NRC (1994) for quails in the rearing and production periods respectively. Poultry Feed Poultry industry is closely connected to the primary agricultural production and form an essential component of the food chain. According to Kleyn (1992) feed cost represents 60-80% of the economic inputs in the commercial poultry industry. Nazri (2003) reported that in poultry production

13 the most important component is the ratio amongst the feed and egg/meat. The general objective of poultry nutrition is to maximize the economic production performance of birds. Diets are formulated by least cost linear programme to provide specified level of nutrients that are needed for optimum performance. The main production criteria are growth rate, feed conversion ratio health and body composition (E. Sonu, 2000). According to Smith et.al., (1979) the goal of modern animal nutrition is to provide as economically as possible a diet which will meet nutrient requirements of an animal for specific production and function. It appears that the manufacturers are aiming at high profit margins instead of focusing on quality of their products (Jones, 2005). It is very important that only quality feeds from all angles as listed by Okoli, et.al., (2009) and Omede (2008) be fed to animals so as to maximize performance and production. Feed plays an important role in economics of poultry production. It constitutes about 60% to 70% in cost of production of eggs and poultry meat (North and Bell, 1990). A balanced poultry ration is prepared based on cereals for energy, vegetable and animal protein source for amino acids and additives containing vitamins and minerals (Scott et.al., 1976). Feed for poultry production are composed largely of grains such as corn, wheat on barley, oil seeds, cake meal (originating mainly from oil producing seeds such as soybeans), sunflower seeds, peanuts, cotton seed and protein products of animal origin such as fish meal, meat and bone meal, slaughter house offals and feather meals (Bale et.al., 2002). Since these feed are expected to be the

14 sole source of nutrition of the birds, they usually contain essential mineral and vitamin additives (Dhand et.al., 1998). The poultry industries rely on the supply of ready-to- use feed from feed mills for handling, unloading, grinding of grains, mixing and usually pelleting of the mixed ration. (Aganaga et.al., 2000). These packaged feed from feed mills constitute the main source of feed for poultry farmers. Poultry feed component of plant and animal origin are commonly contaminated with microorganism, mostly bacteria and fungi and /or insect. Most of the commercial poultry farmers depend on commercial feed for their stock. It is expected that poultry nutritionist have to quantity resultant losses in birds performance when birds are fed sub-standard commercial diets compared to the standard ones. In recent times it has been noted that most commercial feed failed to meet up with the nutrient requirement of birds. Ogunwolere and Onwuka (1997) reported that apart from the highest crude fibre content in most commercial feeds, the recommended and noticeable low crude protein observed in some commercial livestock feed, the finished feed and feed ingredients are adulterated with saw dust, sand and maize bran. Chemical composition of quail meat The valuable taste and dietary properties of quail meat are pivotal in determining the growing interest of consumers to this product (Genchev et.al., 2008). The quality and composition of meat are influenced by numerous factors namely the genotype of birds. (Le Bihan -Dual E 2004; Genchev et.al., 2005), feeding mode (Genchev 2003; Genchev et.al., 2007) and slaughtering age

15 (Genchev et.al., 2004). Poultry meat quality is determined by two extremely important traits- the appearance and meat consistency (Fletcher 2002). Meat tenderness is more important in the final quality determination. The dietary value of meat is mostly defined by its composition and the ration among the different group of nutrients. One criterion for meat evaluation is its protein content and especially the content of essential amino acids. There are differences between pheasants raised in captivity and wild pheasants not only in the carcass value but also in the chemical composition of muscles as reported by Saeki and Kumagai (1990). Tucak et.al., (2008) found that the meat of wild pheasants content more protein and less fat, thus having a higher biological value than the meat of artificially reared pheasants. Differences between breast and thigh muscles in pheasants are also discussed by Petkov (1984). According to Lazer (1990), the most important mineral substance in poultry meat are potassium (0.4%), phosphorus (0.2%), sodium (0.09%) etc. Protein are the major component of dry matter of meat, the protein content in the muscles is variable and depend on the function of a particular tissue (Ingr, 1996). Histology of Gonads Birds possess well developed reproductive organs. Male birds invariably have on pair of testes. The females, unlike male, possess only one functional ovary in the left side. Avian gonads, as that of other vertebrates, perform dual function, i.e., production of germ cells and secretion of gonadal hormones.

16 Testis Testis are located in dorsal posterior of the abdominal cavity in very close proximity to kidney. Each testis is encapsulated in a membrane called tunica albuginea. Tunica albugnia enclose a large number of fine and coiled seminiferous tubules. Each tubule is surrounded by a membrane called tunica propria. The inner side of tunica propria is lined by primary spermatogonia which divide mitotically and produce secondary spermatogonia during active phases of breeding cycle. Primary spermatocytes are formed by mitotic division of secondary spermatogonia, spermatids are transformed into spermatozoa by the process of spermiogenesis. Mature spermatozoa are present in bunches in the lumen of the seminiferous tubules during the peak breeding phase. Interstitial cells are concentrated in inter-tubular spaces of inactive testes. However, interstitial cell are scattered in inter tubular space during progressive and breeding phases. Generally, the number of interstitial cells increases with the activity of the testis (Dominic, 1960; Thapliyal, 1961). Shape, size and histology of the testis vary with the phase of the breeding cycle, the size being maximum during the breeding phase. Ovary In Indian birds, as in temperate zone, only left ovary reaches to functional development, and the right ovary remains rudimentary. Ovary is white in colour and irregular in shape. The size of the ovary varies from species to species. Ovary is covered by a layer of germinal epithelium which gives rise to primary and secondary follicles. The size and the weight of ovary changes

17 with the phases of breeding cycle. The medullary portion of ovary is essentially made up of highly vascularised connective tissue. Total number of ovarian follicles runs in thousand, however, it varies from species to species and individual to individual. The follicles move into the stroma and later on secrete a striated polysaccharide membrane called zona pellucides around the oocyte. The layer of follicle cells surrounding the zona pellucida constitutes corona radiate. The graffian follicle migrates to the surface of the ovary and ruptures releasing the oocyte (now the secondary oocyte) which has so far undergone maturation division, making its way to the fallopian tube. Within the graffian follicle, cells secrete etc. estrogens which promote secondary sex characters, development of the oviduct and courtship behaviour