Effects Of Windy Velocity On Nutrient Metabolism And Serum Physiological And Biochemical Indexes Of Sheep

In the winter,the northern of China would be affected by low temperature.Low temperature causes livestock to use nutrients for heat production to maintain their body temperature,reducing livestock productivity and feed utilization,which seriously hinder the development of animal husbandry.In addition,the northern of China is accompanied by strong northwest winds in winter,and the wind chill effect caused by strong winds aggravates the impact of cold stimulation on livestock.The test aimed to study the effects of low temperature and cold stimulation caused by wind chill effect on index about sheep productivity,and to further understand the mechanism of low temperature and cold stimulation caused by wind chill effect on sheep productivity,and provide reference for winter sheep breeding.Twelve of the 6-month-old hybrid ewes(Small Tail Han sheep × Hu sheep)were selected and divided into three test groups,including: I,II and III.The test was divided into a control group and the cold stimulation treatment groups according to the treatment conditions.The test sheep of the first test group was used as a control group in the sheepfold.The test sheep of the II and III groups were subjected to low temperature and windy velocity treatment under low temperature as test treatment groups.The test treatment groups were divided into four treatments according to different wind speed treatments: no windy velocity treatment group(average windy velocity was less than 0.5 m/s),and low,medium,high windy velocity treatment group(average windy velocity was 3 m/s,4 m/s,5 m/s).The test was carried out in two stages.In the first stage of the test,the test sheep of groups I,II and III were respectively subjected to control group,no windy velocity under low temperature,and low windy velocity treatment under low temperature,immediately after the end of the first stage test.In the second stage of the test,the sheep of Groups II and III were treated with moderate windy velocity and high windy velocity under low temperature.There are no intervals between the two phases for 5 days in each phase.Physiological indicators and serum were collected from the third day to the fifth day of the experiment,and the corresponding indicators were analyzed.The result of test showed:(1)The ADG of sheep were significant negatively correlated with the intensity of cold stimulation(P<0.05),while the duration of cold exposure had no significant effect on ADG(P>0.05).Low temperature reduced the feed intake and apparent digestibility of sheep(P<0.05).However,stronger cold stimulation caused by the cold effect increased the feedintake and apparent digestibility of sheep(P<0.05).The average daily gain(ADG)of sheep decreased with the increase of cold stimulation(P<0.05).(2)The energy metabolism,calcium metabolism,phosphorus metabolism and nitrogen metabolism of sheep were significantly correlated with the intensity of cold stimulation(P<0.05),while the duration of cold exposure had no significant effect on these indexes(P>0.05).The apparent digestibility of gross energy,Apparent Digestibility of phosphorus and apparent digestibility of nitrogen of sheep increased first and then increased with the deepening of cold stimulation.The stronger cold stimulation significantly decreased the apparent digestibility of calcium of sheep.(3)The sodium,phosphorus,calcium,ghrelin,growth hormone,aspartate aminotransferase,and alanine aminotransferase in serum of sheep were significantly correlated with the intensity of cold stimulation(P<0.05),while the duration of cold exposure had no significant effect on these indexes(P>0.05).With the cold stress caused by the cold effect,the content of sodium and ghrelin in serum of sheep significantly decreased.The content of phosphorus and calcium in serum of sheep significantly increased,and the content of growth hormone and aspartate aminotransferase increased first and then stabilized.In summary,the stronger cold stimulation caused by the wind chill effect significantly affected production capability of sheep,and the cold exposure time had no significant effect on it.Cold stimulation can obstruction the normal metabolism of nutrients of sheep,making it impossible to exert its own potential of production capability.the stronger cold stimulation caused by the wind chill effect forced the sheep to improve the digestion and utilization of nutrients to obtain more energy,but the energy obtained was mostly lost in the form of heat,and couldn’t be used for its own growth process,which caused the waste of nutrients in the feed.