| Hormones play an important role in the physiological regulation of mammals.Thyroid hormones are secreted by the endocrine organ,the thyroid gland,and consist mainly of T3(Triiodothyronine)and T4(Tetraiodothyronine),which have crucial roles in metabolism,energy homeostasis and reproduction.Leptin is a protein-like hormone secreted mainly by the white adipocytes of animals,and as an important endocrine regulator,it plays an important regulatory role in the activities of feeding,energy metabolism and fat storage in animals.Changes in food can cause changes in energy or nutrition,which can be reflected in the hormone levels in the animal’s body.In addition,factors such as season,age,and sex may also affect the hormone levels of the animal.To investigate the relationship between thyroid hormone and leptin content and food intake,season,age,and sex of Fran(?)ois’langur(Trachypithecus francoisi)under food-altered conditions,the investigators selected a total of14 individual Fran(?)ois’langurs,including one adult female,four adult males,four subadult females,and five subadult males,from eight cages at the Rare Animal Reproduction Center,Wuzhou,Guangxi,from December 2021 to March 2022 and from May 2022 to November2022 for the experiment.Fran(?)ois’langurs were fed according to three set food gradients(original:traditional food composition;gradient 1:increase of about 12%green feed and decrease of 12%concentrate;gradient 2:increase of about 22%green feed and decrease of22%concentrate),and their feed intake was recorded and calculated,and their fresh fecal samples were collected after feeding.The hormone content in the feces was determined by enzyme-linked immunoassay and the results of the study were as follows:1.Overall,the amount of food taken by Fran(?)ois’langurs at each of the three food gradients was:original feeding gradient:177.974±42.698 g,gradient 1:229.789±80.306 g,and gradient 2:263.537±74.177 g.There was a significant difference in intake between the three food gradients(X~2=24.909,df=2,P=0.005).There were significant differences in food intake between the three food gradients for adult females(X~2=8.860,df=2,P=0.012),adult males(X~2=10.085,df=2,P=0.006)and subadult females(X~2=10.177,df=2,P=0.006)were also significantly different,with mean values of feed intake for each age-sex group:adult females:247.769±75.470 g,adult males:219.650±51.235 g,subadult females:210.549±50.241 g,and subadult males:216.729±75.055 g.Fran(?)ois’langurs ate more green fodder when cake was reduced.The green fodder intake:original feeding gradient<gradient 1<gradient 2.2.T3 levels of Fran(?)ois’langurs at the three food gradients were:original feeding gradient:0.582±0.103 ng/g,gradient 1:0.629±0.124 ng/g,and gradient 2:0.665±0.079ng/g.T3 levels increased with increasing green forage intake(original feeding gradient<gradient 1<gradient 2),but the magnitude of the increase did not reach significance differences:adult females(X~2=0.045,df=2,P=0.978),adult males(X~2=3.326,df=2,P=0.190),subadult females(X~2=3.136,df=2,P=0.208),subadult males(X~2=1.417,df=2,P=0.492).Seasonal changes in temperature caused some variation in T3 content,with T3levels being lowest in summer,when they were 0.577±0.070 ng/g,and highest in winter,when they were 0.653±0.119 ng/g,but there was no significant difference in overall T3content between the four seasons(X~2=1.045,df=3,P=0.790).In addition,age and sex had no significant effect on T3 content,with no significant difference in T3 content between age-sex groups at the original feeding gradient(X~2=0.653,df=3,P=0.884),at gradient 1(X~2=0.630,df=3,P=0.889)and gradient 2(X~2=0.799,df=3,P=0.850)were also not significantly different.There were no significant differences in T3 content between age-sex groups in spring(X~2=1.833,df=3,P=0.608),in summer(X~2=1.308,df=3,P=0.727),in autumn(X~2=0.846,df=3,P=0.838),and winter(X~2=3.308,df=3,P=0.347)were also not significantly different.3.Fran(?)ois’langurs had the highest T4 levels in the original feeding gradient:17.813±1.547 ng/g and the remaining two food gradients:gradient 1:16.913±1.335 ng/g and gradient 2:17.033±2.379 ng/g,but there were no significant differences in T4 levels across food gradients for any of the age-sex groups:adult females(X~2=0.712,df=2,P=0.700),adult males(X~2=1.878,df=2,P=0.391),subadult females(X~2=1.803,df=2,P=0.406),subadult males(X~2=0.894,df=2,P=0.640).T4 levels in adult females,adult males,and subadult males were all highest in spring with levels of 18.936±0.526 ng/g in adult females,17.554±1.614 ng/g in adult males,and 17.943±2.690 ng/g in subadult males,respectively,but there were no significant differences in T4 levels between the four seasons overall(X~2=1.045,df=3,P=0.790).Furthermore,age and sex had no significant effect on T4 content,with no significant differences between age-sex groups at the original feeding gradient(X~2=2.051,df=3,P=0.562),at gradient 1(X~2=0.487,df=3,P=0.922)and gradient 2(X~2=0.199,df=3,P=0.978)were also not significantly different.There were no significant differences in T4 content between age-sex groups in spring(X~2=1.167,df=3,P=0.761),in summer(X~2=2.897,df=3,P=0.408),in autumn(X~2=1.154,df=3,P=0.764),and winter(X~2=1.359,df=3,P=0.715)were also not significantly different.4.Leptin levels of Fran(?)ois’langurs at the three food gradients were:original feeding gradient:36.132±3.472 ng/g,gradient 1:38.155±6.942 ng/g,and gradient 2:42.266±5.565 ng/g.Leptin levels in all age-sex groups were highest at gradient 2,with subadult males having significantly different leptin levels across the three food gradients(X~2=6.053,df=2,P=0.048),with no differences between the remaining age-sex groups:adult females(X~2=0.848,df=2,P=0.654),subadult females(X~2=3.848,df=2,P=0.146),adult males(X~2=3.598,df=2,P=0.165).In general,leptin levels in the four seasons were:spring:38.756±4.488 ng/g,summer:38.861±8.199 ng/g,autumn:41.547±5.544 ng/g,and winter:37.098±4.099 ng/g,respectively,with no significant differences in leptin levels between the four seasons(X~2=1.045,df=3,P=0.790).In addition,age and sex had no significant effect on leptin content,with no significant difference in leptin content between age and sex groups at the original feeding gradient(X~2=1.809,df=3,P=0.613),at gradient 1:(X~2=1.154,df=3,P=0.764)and gradient 2(X~2=0.375,df=3,P=0.945)were also not significantly different.There were no significant differences in leptin content between age-sex groups in spring(X~2=2.667,df=3,P=0.446),in summer(X~2=2.744,df=3,P=0.433),in autumn(X~2=1.923,df=3,P=0.589),and winter(X~2=5.359,df=3,P=0.147)were also not significantly different.Based on the results of the study,when the proportion of concentrate was reduced and the proportion of green feed was increased in the food composition of captive Fran(?)ois’langurs,the intake of Fran(?)ois’langurs changed significantly,and this change had some effect on the thyroid hormone content of Fran(?)ois’langurs but did not reach a significant difference,and had a more significant effect on the leptin content.Based on preliminary speculation of hormonal trends,the body fat and basal metabolic rate of Fran(?)ois’langurs may increase correspondingly with the increase of green feed and the decrease of the percentage of concentrate feed. |
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