Changes in milk production and chemical composition, rumen digestion and fermentation parameters of Turki-Qashqai ewes in the two climates of summer and winter habitat under nomadic conditions

Sheep breeding in nomadic farming systems is significantly affected by climatic conditions. Among the various climatic stresses that sheep face, heat stress seems to have severely destabilized the productivity of these animals. Exposure to heat stress affects discretionary feed consumption and increases maintenance requirements, resulting in side effects such as reduced production and economic losses. Given the significant effects of climate on the performance and production characteristics of sheep in nomadic farming systems, it seems necessary to investigate the performance of native sheep in areas with tropical and cold climates. Therefore, this study was conducted to investigate the production and composition of milk, fermentation and rumen digestion parameters, and nutrient intake in Turki-Qashqai ewes in the two climates of summer and winter habitat.
Materials and Methods: This experiment was conducted in a completely randomized design with two treatments (summer and winter habitat climates) and the same number of repetitions in each treatment (n = 8) in two areas of winter habitat (Afzer, Qir-o-karzin city, Fars province as winter habitat) and summer habitat (Kamaneh, Semiram city, Isfahan province as summer habitat) for 21 days; including 14 days of habituation period and 7 days of sampling and it was done with the same ration. For this purpose, out of 16 Turki-Qashqai lactating ewes with an average lambing belly of 2.81±0.21 (mean ± standard error), live weight 44.81±0.84 Kg, milk production 306.06±5.65g hot and the physical score was 3.23±0.07. To measure milk production, milk production was determined daily by weighing lambs before and after milk consumption. To analyze the chemical composition of milk, the sample prepared on the last 3 days of the experiment was stored in a freezer at -21°C and its composition was determined after the end of the experiment. Daily feed intake was recorded and the daily nutrient intake was determined by determining the chemical composition of the feed sample and the feed residue. Nutrient digestibility was determined by measuring acid-insoluble ash. Sampling of rumen fluid was performed on the last day of the experiment and 2 hours after morning feeding, and the pH and percentage of volatile fatty acids of the samples were measured. The statistical analysis of the results obtained by the Mixed Model method of SAS statistical software (2003, 9.1) was used and the comparison of means was done using Tukey Kramer test at a significance level of 0.05.
Results: The results showed that climate type had no effect on milk production (P>0.05) and among milk components, only milk ash concentration had a significant effect, such that milk ash content in ewes from winter habitat region was higher than that in summer habitat region (P≤0.05). Also, the effect of sampling time and the interaction effect of sampling time on climate was also significant only on milk production (P≤0.05). The results of the effect of climate type on rumen fermentation parameters of ewes also showed that climate type had a significant effect on acidity, acetate concentration, propionate, propionate to acetate ratio, total ammonia, and protozoa (P≤0.05). Also, the results showed that ewes in the summer pasture had higher weight at the end of the experimental period (P≤0.01) and it was found that the climate type had a significant effect on the consumption of dry matter, organic matter, water and NDF, so that the consumption of dry matter and NDF in the summer pasture and the consumption of organic matter and water in the winter habitat were higher (P≤0.01). In addition, the results showed that the digestibility of dry matter, organic matter and neutral detergent insoluble fiber in the digestive tract of ewes located in the summer pasture area