The relation between oxidative status, milk quality and conception rate in dairy goats supplemented with vitamin C

الملخص EN

Pregnant Agamy does were used in this experiment to evaluate the effects of Vitamin C (Vit C) supplementation as antioxidant agent to improve the performance of dairy goats during the evidence of oxidative stress (OS) in peri-parturient period.

The does under experiment (n = 16) were assigned randomly into control and supplemented groups (n = 8 / group).

The control group fed control diet without supplement and the supplemented group fed control diet plus Vit C 75 mg / kg of body weight.

Dietary supplementation began approximately one month before the expected kidding date till two months post-kidding.

Compared to the control does, it was noticed that Vit C supplementation significantly increased (P < 0.05) the conception rate (62.5 % vs.

25 %), the weaning weight (WW) (7.21 vs.

5.00 kg) as well as the average daily gain rate (DGR) (53.94 vs.

34.85 g / d) in the kids of the Vit C supplemented group.

Vit C supplementation significantly (P < 0.05) increased serum level of T3 from day 45 to day 60 and of T4 from day 30 to day 60 post-kidding.

Meanwhile, serum cortisol level was significantly decreased (P < 0.05) from day 30 to day 60 post-kidding in the Vit C supplemented group.

Also, there was a significant increase (P < 0.05) in serum total antioxidant capacity (TAC) from day 15 post-kidding and glutathione peroxidase (GPX) from day 30 post-kidding till the end of the experiment in the Vit C supplemented group as compared with the control one.

Meanwhile, there was a significantly decrease (P < 0.05) in serum Malondialdehyde (MDA) level from day 45 post-kidding and nitric oxide (NO) level from day 15 post-kidding till the end of the experiment.

Concerning the effect of Vit C supplementation on milk quality, it was found that Vit C supplementation significantly (P < 0.05) improved most of milk components especially fat, lactose, milk urea level (MUL), total solids (TS) and solid not fat (SNF) ; meanwhile there was a non-significant increase in protein % all over the experiment period.

Moreover, both somatic cell counts (SCC) and the infection rates represented by the total bacterial count (TBC) were significantly (P < 0.05) decreased in the Vit C supplemented group when compared with the control one.

It was concluded that Vit C supplementation in dairy does around the peri-parturient period can improve the unfavorable effects of OS ; this reflected on their milk quality and post-kidding conception rate and enhancement of growth rate as well as weaning weight of their kids.