Effect of short-term nutritional supplementation of green microalgae on some reproductive indicators of Anglo-Nubian crossbred goats

Abstract

Background and aim: Despite the wide spectrum of uses, one of the chief drawbacks to expanding microalgae as a food supplement in livestock is the lack of a regimen protocol with established dosage and time length of supplementation. Therefore, this study aimed to investigate the effect of short-term supplementation with increasing doses of microalgae on ovarian response in goats reared in northeast Brazil.

Materials and methods: Twenty-eight goats had their follicular waves synchronized using three injections of a prostaglandin analog at 7-day intervals. Goats were allocated to groups that received daily oral Chlorella supplementation for 7 days, respectively: 5 g, GMA5 group (n = 7), 10 g (GMA10; n = 7), and 20 g (GMA20; n = 7). The control group (GMA 0; n = 7) received a drench of water.

Results: The groups showed a quadratic increase (p = 0.0156) in kidney fat thickness but there was a significant reduction in dry matter intake in the GMA20 group. The GMA20 group showed higher glucose levels and glutathione peroxidase (p < 0.05). There was a decrease in plasma cholesterol (p < 0.05) in the 10 and 20 g treatments. The number of total follicles increased quadratically. Follicles <3 mm increased linearly (p = 0.0113) for microalgal supply. The GMA10 and GMA20 groups had the highest values (p < 0.05) among the treatments. After inducing ovulation, there was a significant increase in follicles >3 mm in the GMA10 group, which also showed a greater (p < 0.05) area of intraovarian blood perfusion and pulsatility index of the ovarian artery.

Conclusion: We conclude that for 7 days of supplementation, the administration of 10 g of microalgae appears to be the most efficient dosage for stimulating the ovarian response in tropical goats.

Keywords: Doppler; follicles; goat; microalga; ovarian blood flow; ovarian response.

Figure-1

General experimental design, including dietary treatments and hormonal protocol.

Figure-2

Peripheral glucose (a) measured during sampling every 6 h (06:00 h am, 12:00 h am, 18:00 h pm) on the 6^th day. No interactions and effects of the sampling interval were verified in cholesterol and glutathione peroxidase. (b and c) Overall mean group levels. Values are expressed as mean ± standard error of the mean. ^a,b,cp < 0.05 differences between groups.

Figure-3

Number of follicles >3 mm counted after the third application of prostaglandin F2 alpha (PGF2α) analog and ovulatory rate (a) determined by ultrasonography after the third application of PGF2α analog. Color Doppler intraovarian area of the ovary and pulsatility index of the ovarian artery recorded at ovulation induction (b). Values are expressed as mean ± standard error of the mean. ^a,bp < 0.05 differences between groups.