| This research aimed to study the effects of different housing environment on the growth performance,basic physiological indicators,blood biochemical indicators,hormone indicators,immune and antioxidant function of lambs in winter,and reveal the selfregulation and protection mechanism of the lambs under cold stress,so as to provide a reference for the scientific management of lambs in winter in Inner Mongolia.A total of 60two-month-old Dorper × Mongolian crossbred female lambs with similar body weight were randomly divided into 4 treatments with 5 replications and 3 lambs in each replication.The four treatment groups were: house with opaque roof(IOP),outdoors in fence(OUT),house with playground(IPG),house with semitranslucent roof(ITR),and the trial period was 28 days.Weighed on day 1 and 28 to calculate average daily weight gain(ADG)and average daily feed intake,and measured scalp,ear and abdominal skin temperatures,rectal temperatures and respiration rate on day 1,14,21 and 28.The blood samples were collected on day 7,14,21 and 28.Serum was isolated,leukocytes were collected,and serum heat shock protein(HSP),hormones and biochemical indexes,the serum immune and antioxidative indexes and the related gene expression levels were measured.The result was shown as following:(1)ADG of the lambs in OUT and IPG was significantly less than that in IOP and ITR(P<0.05).The skin temperature on head and ear of the lambs in IOP and ITR groups were significantly higher than that in OUT and IPG groups(P<0.01).The respiration rate of lambs in IOP was significantly higher than in the other three groups(P<0.01).(2)On day 7,the contents of adrenotropin(ACTH),cortisol(COR)and adiponectin(ADPN)in serum of lambs in OUT was significantly increased compared to those in the other three groups(P<0.05),the serumal GLU level of lambs in OUT significantly higher than that in ITR(P<0.05).On day 14,the levels of ACTH,COR and ADPN in serum of lambs in OUT significantly increased compared to those in IOP and ITR(P<0.05),the serumal GLU content in OUT was significantly increased compared to that in ITR(P<0.05),the TG content in OUT was significantly higher than that in the other three groups(P<0.05).On day 21,the serumal ACTH content of lambs in OUT and IPG were significantly higher than that in ITR(P<0.05).Serumal COR level of lambs in OUT was significantly higher than that in ITR,and the serumal contents of ADPN and insulin(INS)of lambs in OUT and IPG were significantly higher than those in IOP and ITR(P<0.05).The levels of GLU and NEFA in serumal of lambs in OUT were significantly higher than those in IOP and ITR groups(P<0.05),and the TG content of lambs in OUT was significantly higher than that in the other three groups(P<0.05).On day 28,the serumal ACTH content of lambs in OUT and IPG was significantly higher than that in ITR(P<0.05),the serumal HSP90 content of lambs in OUT and IPG was significantly higher compared to that in IOP and ITR(P<0.05),and serumal INS level of lambs in OUT and IPG were significantly reduced compare to that in IOP and ITR(P<0.05).The serumal contents of COR and ADPN of lambs in OUT were significantly higher than those in ITR(P<0.05),the levels of TG,GLU and NEFA in serumal of lambs in OUT were significantly higher than those in the other three groups(P<0.05),and the LDH level was significantly higher than that in ITR(P<0.05).As the experiment went on,the gene expression levels of heat shock transcription factor 1,HSP70 and HSP90 in leukocytes of lambs in OUT and IPG were significantly increased compared with those in IOP and ITR.(3)On day 14,the serumal T-SOD activity of lambs in OUT and IPG was significantly lower than that in IOP and ITR,and serumal MDA content was significantly higher than that of the IOP and ITR(P<0.05).On day 21,the serumal activities of CAT,GSH-Px and T-SOD of lambs in OUT and IPG were significantly lower than those in IOP and ITR,and serumal MDA content was significantly higher than that in IOP and ITR(P<0.05).The serumal Ig G content of lambs in ITR group was significantly higher than that of the other three groups,and serumal TNF-α content was higher than that in OUT(P<0.05).On day 28,the activities of CAT,GSH-Px and T-SOD in serumal of lambs in OUT and IPG were significantly lower than those in IOP and ITR,and serum T-AOC was significantly lower than that in IOP and ITR(P<0.05),and MDA content was significantly higher than that in IOP and ITR(P<0.05).The serumal contents of Ig G,Ig A and TNF-α of lambs in ITR were significantly higher than those in the other three groups,and serumal IL-4 content was significantly higher than that in OUT and IPG(P<0.05).As the experiment went on,compared with those of the lambs in IOP and ITR,the expression levels of immune-related gene receptor interacting protein 2,nuclear transcription factor κB(NF-κBp50),NF-κBp65,IL-1β,leukocytes of lambs in OUT and IPG were significantly higher(P<0.05),while the expression levels of antioxidantrelated genes nuclear transcription factor 2,CAT,GPX-Px,SOD1 and SOD2 were significantly lower in OUT and IPG(P<0.05).In summary,under the low temperature conditions in winter,outdoor feeding and casual exercise caused cold stress,oxidative stress and immunosuppression,inhibited growth performance in lambs.And increased expression of heat shock protein(HSP)gene plays an important role in the survival of lambs in low temperature.Feeding in house with opaque roof and house with semitranslucent roof alleviated the above passive phenomena,and feeding in house with semitranslucent roof improved the immune function of lambs. |
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