Document Type : Research Paper
Authors
1 Department of Animal Sciences, Faculty of Agriculture, University of Ilam, Ilam, Iran. Email: Kocheki.mozafar@gmail.com
2 Corresponding Author, Department of Animal Sciences, Faculty of Agriculture, University of Ilam, Ilam, Iran. Email: m.hamsolahi@ilam.ac.ir
3 Department of Animal Sciences, Faculty of Agriculture, University of Ilam, Ilam, Iran. Email: f.fatahnia@ilam.ac.ir
4 Department of Veterinary Medicine, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran: drvetfarzadi@gmail.com
5 Department of Animal Sciences, Faculty of Agriculture, University of Ilam, Ilam, Iran. Email: Y.mohammadi@ilam.ac.ir
Abstract
Introduction Sheep producers would benefit from the opportunity to change offspring sex ratio towards their preferred gender. For example, male lambs have higher average daily gain and better carcass quality than female lambs. Thereby reaching a higher market weight over a set time period. However, sheep interprises require breeding females, which may lead to a higher sale price of first-cross ewes at weaning. Maternal nutrition has potential to affect many aspects of reproduction outcomes including ovulation rate, pregnancy rate, embryo survival and sex ratio of offspring. It has been indicated that some dietary nutrients including glucose and polyunsaturated fatty acids as well as total energy could affect offspring sex ratio in different mammalian species. The influence of dietary mineral balance affect offspring sex ratio in sow and ewe. Experiments on pre- and postconception mechanisms demonstrated that these mechanisms influence the sex ratio in mouse embryos. Some studies based on theories that sperm carrying the X or Y chromosome favored different vaginal pH. Therefore, it has been suggested that the pH of the vagina at the time of fertilization may have a differential effect on X- or Y- sperm, thus affecting the sex of the offspring. Feeding a negative dietary cation- anion difference (DCAD) in prepartum dairy cows improves Ca metabolism in the peripartum cow through instigating a mild metabolic acidosis via feeding excess dietary anions. We hypothesized that feeding diet with negative DCAD around mating would decrase the pH of veginal fluid and subsequently might affect lamb sex ratio in Kurdish ewes. Therfore, the aim of this experiment was to investigate the effect of dietary DCAD of flushing diet around mating on plasma metabolites and hormones concentrations and reproductive performance of Kurdish ewes as well as lamb sex ratio.
Materials and Methods Eighty four Kurdish ewes with average BW of 40±5 kg, BCS of 2.75±0.25 and 2-4 years were used. Ewes were divided into two similar groups and randomly assigned to experimental diets. Experimental diets consisted of 1- cationic diet (diet with DCAD of +193 mEq/kg of DM) and 2- anionic diet (diet with DCAD of -21 mEq/kg of DM). Ewes fed experimental diets from 2 weeks before estrous synchronization till 3 weeks after mating. Estrous of ewes were synchronized by 9-d intravaginal sponge and intramuscular injection of 5 mL vetaroline at the day of sponge removal. Blood samples were collected from jugular vein using 10-mL evacuated tube containing sodium heparin at the day before the beginning of experiment, at the day of sponge removal and at the day of estrous and mating. Plasma concentrations of total cholesterol, total protein, urea nitrogen, glucose, triglyceride, insulin, progesterone, estradiol, testosterone, calcium, magnesium, potassium and sodium were determined.
Results and Discussion Experimental diets had no effect on estrous response, fertility rate, lambing rate, twining rate and birth BW and sex of lambs. Ewes fed anionic diet had higher plasma progesterone and lower estradiol levels at the days of sponge removal and estrous than those fed cationic diet (P<0.05). Plasma concentrations of total protein, glucose, sodium, potassium, calcium and magnesium did not influence by DCAD of flushing diet. Whereas, feeding anionic diet around mating decreased plasma concentration of total cholesterol and triglyceride and increased urea nitrogen (P<0.05).
Conclusion According to these results, feeding flushing diet with different DCAD around mating had no effect on lamb sex ratio in Kurdish ewes.
Keywords
)