Response of growing ruminants to diet in warm climates: a meta-analysis
2015
Salah, N. | Sauvant, D. | Archimède, H.
The aim of this work was to establish the response of growing sheep, goats and cattle to different nutritional environments. Data from 590 publications representing 2225 treatments were analysed. The results showed that each 10% increase in NDF was accompanied by 0.11 g/kg live weight (LW) and 0.32 g/kg metabolic live weight (LW⁰.⁷⁵) decreases in DMI. Otherwise, the response of DMI to CP (CP%DM) content was curvilinear (P<0.01), without any significant difference in the slope between species. The percentage of concentrate (% CC) affected DMI curvilinearly, without any significant difference between species. This meta-analysis demonstrated the negative linear effect of NDF and the quadratic effect of CP concentration on organic matter digestibility (OMd). For growth performance, the three species responded curvilinearly to variations in metabolisable energy intake (MEI MJ/kg LW⁰.⁷⁵) and digestible CP (DCPI g/kg LW⁰.⁷⁵) intake (P<0.01). At the same level of MEI, average daily gain (ADG) varied with CP contents of the diet, and only the intercept differences were significant between the three levels (P=0.07). At the same level of DCPI, ADG varied with energy level (below maintenance (LE−−), 1 to 1.2×maintenance (LE−), 1.2 to 1.4× maintenance (ME+−), and >1.4, corresponding to maximum growth (HE+)). No significant difference was observed between LE−− and LE−, and no significant difference was observed between ME+− and HE+. For nitrogen balance, no difference was observed between species for a given level of nitrogen intake.
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