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Ehsan Mahjoubi

Mahjoubi, E., H. Amanlou, M. Hossein Yazdi, N. Aghaziarati, G. R. Noori, C. I. Vahl, B. J. Bradford and L. H. Baumgard
A supplement containing multiple types of gluconeogenic substrates alters intake but not productivity of heat-stressed Afshari lambs
یک مکمل حاوی چند نوع سوبسترای گلوکوژنیک خوراک مصرف را در بره های افشاری تحت تنش حرارتی تغییر می دهد ولی عملکرد تولیدی را نه.
Abstract


Thirty two Afshari lambs were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments to evaluate a nutritional supplement designed to provide multiple gluconeogenic precursors during heat stress (HS).  Lambs were housed in thermal neutral (TN) conditions and fed ad libitum for 8 d to obtain covariate data (period 1: P1) for the subsequent experimental period (P2).  During P2, which lasted 9 d, half of the lambs were subjected to HS and the other 16 lambs were maintained in TN but pair-fed (PFTN) to the HS lambs.  Half of the lambs in each thermal regime were fed (top-dressed) 100 g/d of a feed supplement designed to provide gluconeogenic precursors (8 lambs in HS [HSG] and 8 lambs in PFTN [PFTNG]) and the other lambs in both thermal regimes were fed only the basal control diet (HSC and PFTNC).  Heat stress decreased DMI (14%) and by design there were no differences between the thermal treatments, but HSG lambs had increased DMI (7.5%; P < 0.05) compared to the HSC.  Compared to PFTN lambs, rectal temperature and skin temperature at the rump, shoulder and legs of HS lambs were increased (P < 0.05) at 0700 and 1400 h.  Rectal temperature at 1400 h decreased for HSG (0.15 ± 0.03°C; P < 0.05) compared to HSC.  Despite similar DMI between thermal treatments, ADG for HS and PFTN lambs in P2 was decreased 55 and 85%, respectively, compared to P1 (P < 0.05).  Although the pre-feeding glucose concentration was not affected by thermal treatment or diet, HSG had increased post-feeding glucose concentration compared to HSC (P < 0.05).  In contrast to the glucose responses, circulating insulin was only influenced by thermal treatment; HS lambs had increased insulin concentration (P < 0.01) pre-feeding and decreased concentration (P < 0.05) post-feeding compared to PFTN lambs.  Heat-stressed lambs had decreased NEFA concentration pre-feeding (P < 0.01), but not post-feeding, relative to PFTN lambs.  Although this nutritional strategy did not affect ADG, the lower rectal temperature in HSG lambs indicates that dietary inclusion of a mixture of glucogenic precursors can potentially benefit animal health during HS.

 

 

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