Effect of stair-step feeding regimen during estrous cycle on follicular development and oocyte quality of Thai-native does

Abstract

The objective of this study was to determine the effect of stair-step feeding regimen during estrous cycle on follicular development and oocytes quality. Sixteen Thai-native non pregnant goats were used with the average age and body weight of 8 months and 17±0.6 kg, respectively. The does exhibited at least 2 normal estrous cycle and were housed in 1 m2 steel cages. Heat detection was daily recorded using a vasectomized buck. The does were randomly assigned into two groups: Control and Stair-step feeding group. In the control group, does were fed 100% of nutrients requirement for growth in puberty periods. Does consumed Ruzi grass hay, DM = 500 g/head/d and concentrate supplemented at 1% of body weight. Total feed intake was 670 g/head/d, (ME = 1.48 Mcal/kg/d,
TP = 55 g/head/d during day 1-42). In the Stair-step feeding group, treatment was divided in two phases: feed
restriction and realimentation. In the first phase, does were fed roughage and concentrate 70% of the average
consumption of control group during day 1-21 (1st estrous cycle). In the second phase, goats were offered 130% of the average consumption of control group during at day 22-42 (2nd estrous cycle). Does were scheduled to determine follicular growth and number, as well as oocyte quality by surgical laparotomy. The results showed that average total feed intake, average daily gain and feed conversion ratio were not statistically different between stair-step and control group (P>0.05). Serum glucose concentrations at 4 h was during realiment phase were greater than control group (P<0.05). Numbers of total follicles in stair-step group were greater than control group (P<0.05). Moreover, Oocyte quality of the treatment group was better (P<0.01) than that of control group in follicular size of 1-3, 4-6 and ≥7 mm. Proliferation cell nuclear antigen (PCNA) was used to establish cell labeling techniques for investigating cell proliferation. In this study was observe differences among regions of the granulosa and theca cell layer. Difference
of follicular size (1-3, 4-6, ≥7 mm) between treatment and control group were compared. The results found that the labeling index in granulosa and theca layer of all follicular size 1-3, 4-6 and ≥7 mm were statistically different between stair-step feeding and control group (P<0.05). These results indicate that stair-step feeding regimen affects fertility improvement in Thai-native does.