Effects of vitamin E and vitamin A supplementation on performance, thyroid status and serum concentrations of some metabolites and minerals in broilers reared under heat stress (32 degrees C)

Abstract

An experiment on Cobb-500 male broilers was conducted to evaluate the effects of vitamin E (α-tocopherolacetate), vitamin A (retinol), and their combination on broiler performance and serum concentrations of triiodothyronine (T 3 ), thyroxine (T 4 ), adrenocorticotropine hormone (ACTH) and some metabolite and mineral concentrations in broilers reared under heat stress (32°C). One day-old 120 broilers were randomly assigned to 4 treatment groups, 3 replications of 10 birds each. The birds were fed either a control diet or a control diet supplemented with either vitamin A (15 000 IU retinol/kg diet), vitamin E (250 mg α-tocopherol-acetate/kg diet), or a combination of vitamin A and E (15 000 IU retinol plus 250 mg of α-tocopherolacetate/kg diet). Considered separately or as a combination, supplemental vitamin A and vitamin E increased feed intake (P = 0.01) and live weight gain (P = 0.03). However, feed efficiency remained similar in all treatments (P = 0.18). Serum T 3 and T 4 concentrations were also higher (P ≤ 0.001) with vitamin A, vitamin E, and vitamin A plus vitamin E groups than those of the control. However, ACTH concentration in serum was lower (P ≤ 0.001) in supplemental dietary vitamin groups compared with control. Serum glucose, uric acid, triglyceride, and cholesterol concentrations decreased (P ≤ 0.001) while protein and albumin concentrations increased (P ≤ 0.001) when both dietary vitamin E and vitamin A were supplemented. Serum activities of serum glutamic oxalate transaminase (SGOT) and serum glutamic pyruvate transaminase (SGPT) were not influenced by dietary vitamin E, vitamin A nor by a combination of vitamin A and vitamin E (P > 0.72). However, serum activity of alkaline phosphatase (AP) increased (P ≤ 0.001) with supplemental dietary vitamin E, vitamin A, or a combination of vitamin A and vitamin E. In addition, supplemental dietary vitamin E and vitamin A resulted in an increase in serum concentrations of both Ca and P (P ≤ 0.001). In general, when a significant effect was found for a parameter, the magnitude of responses to vitamin supplements was greatest with the combination of vitamin A and vitamin E, rather than that of each vitamin supplement separately. The results of the present study show that supplementing a combination of dietary vitamin E and vitamin A offers a good management practice to reduce heat stress-related decreases in broiler performance.

Effects of concomitant selenium and vitamin E administration on thyroid hormone metabolism in broilers

“…Previous studies in different animal species revealed a protective role of vitamin E under various stress conditions (Brzezińska-Slebodzińska 2001; Sahin et al, 2001;Sarandöl et al, 2005). Most notably, in lead induced thyroid dysfunction in mice administration of vitamin E has been shown to maintain ID-I activity and in Se and vitamin E deficient rats vitamin E administration increased hepatic ID-I activity (Yue et al 1998).…”

Heat Stress Impact on Livestock Production

“…These negative effects are found to be greater in poultry with a high potential for growth rate (Cahaner et al 1998;Settar et al 1999). High thermal loads may depress enterocyte proliferation, reduction in villus mass and dry weight per unit length of jejunum (Sahin et al 2001). A number of morphologic and physiologic changes occur in the gastrointestinal tracts of chickens exposed to heat stress.…”

Aplikasi Mengkudu Sebagai Sumber Antioksidan Untuk Mengatasi Stress Ayam Broiler Di Daerah Tropis

“…Sedangkan pada ayam yang dipelihara pada suhu 32 0 C pemberian antioksidan sari buah mengkudu 1.000 ppm dapat memberikan hasil yang sama dengan kadar tiroksin pada ayam broiler yang dipelihara pada temperatur netral. Aktivitas kalenjar tiroid dipengaruhi oleh kondisi lingkungan, pada ayam yang mengalami cekaman panas aktivitas kelenjar tiroid mengalami penurunan (Sahin et al, 2001;Gyorffy et al, 2009) dan akan mempengaruhi sekresi hormon yang dihasilkannya.…”

“…Kadar hormon tiroksin pada ayam yang dipelihara pada suhu 20 0 C yaitu 0,916 µg/dl lebih tinggi dibandingkan dengan ayam yang dipelihara pada suhu 26 dan 32 0 C yaitu 0,596 µg/dl dan 0,366 µg/dl. Hal ini sesuai dengan penyataan Sahin et al (2001) terjadi penurunan konsentrasi hormon T3 (Triiodotironin) dalam sirkulasi darah. Lebih lanjut Decuypere et al (2005) dan Downing dan Bryden, (2002) menyatakan bahwa hormon tiroksin dihasilkan oleh kelenjar tiroid dan Ringer (1976) menyatakan terdapat hubungan antara musim dengan aktivitas kelenjar tiroid, pada musim panas aktivitas kelenjar tiroid rendah dibanding pada musim dingin.…”

“…Lebih lanjut dijelaskan oleh Ichsan (1991) bahwa, peran vitamin C dalam aktivitas tiroid mungkin terkait dengan fungsi vitamin C sebagai transpor elektron, sehingga dapat memberikan elektron dalam reaksi penggabungan dengan iodium dalam pembentukan tiroksin, hal ini dapat menaikkan kadar tiroksin dalam plasma darah. Sesuai dengan fungsi hormon tiroksin yang dihasilkan kelenjar tiroid memegang peranan penting dalam mempercepat pertumbuhan dan metabolisme energi (Sahin et al, 2001). Kusnadi et al (2006) menyatakan, bahwa antanan dan vitamin C berperan baik sebagai antioksidan, sehingga mampu mengatasi turunnya konsumsi ransum dan pertambahan bobot badan pada kondisi cekaman panas.…”