Reproductive characteristics of male and female Japanese quails (Coturnix coturnix japonica) fed diets with different levels of crude protein during the growth and production phases

Abstract

The objective of this study was to evaluate the growth and reproductive performance of male and female Japanese quails fed diets with different levels of crude protein (CP) during the growth (1 to 35 days of age) and production (36 to 96 days) phases. Three hundred one-day-old males, housed in 30 cages (10 birds/cage), and 360 one-day-old females, housed in 10 cages (36 birds/cage), were used in the present study; they were housed as described above until the birds were 35 days of age (growth phase). The treatments tested during this phase included five different levels of dietary CP (18, 20, 22, 24 and 26%), which were reduced by four percentage units for the production phase. During the production phase, the birds were randomly redistributed into 40 laying cages, each with 9 females and 3 males. During all experimental periods, every 3 days, 12 birds of each sex from each CP level were individually weighed, until the birds reached 60 days of age, to estimate the growth parameters using the Gompertz curve. For the production variables, a completely randomized design with five treatments (dietary CP levels) and eight replicates (cages) was used. For the males, there was a linear increase (P<0.05) in the growth maturity rate and a linear reduction (P<0.05) in the maximum growth interval up to the level of 22% CP. A higher weight at growth maturity (P<0.05) was obtained with 18% CP. There was no effect (P>0.05) of CP levels on the semen quality and fertility rate. In females, the highest CP levels (24 and 26%) reduced (P<0.05) the maturity rate and increased (P<0.05) the age of maximum weight gain. The 24% level of CP increased (P<0.05) the weight at maturity, whereas 26% CP reduced (P<0.01) the feed conversion, and the age at first egg, and at 50 and 95% laying; the same CP level increased (P<0.01) the egg mass and egg density. The highest intensity of laying at 47 days of age was obtained (P<0.01) with either 24 or 26% CP. Egg weight was only reduced (P<0.01) when 18% CP was used. The internal quality of the egg was not influenced (P>0.05) by the dietary CP levels. Dietary CP levels influence the overall growth and development of both male and female quails; however, reproductive traits are only affected in females. For both sexes, 26 and 22% CP are recommended during the growth production phases, respectively.