EFFECT OF PARTIAL OR TOTAL SUBSTITUTION OF OAT HAY BY ROSEMARY (ROSMARINUS OFFICINALIS L.) RESIDUES ON GROWTH, DIGESTIBILITY AND NITROGEN RETENTION IN GROWING QUEUE FINE DE L’OUEST LAMBS
Yagoubi Yathreb , Mahouachi Mokhtar, Mekki Ilyes , Smeti Samir , Hajji Hadhami , Atti Naziha
University of Carthage, INRA-Tunisia, Laboratoire de Productions Animales et Fourragères, rue Hédi Karray, 2049 Ariana, Tunisia
yagoubiyathreb@hotmail.fr
The rosemary essential oil production leads after distillation to considerable amounts of residues that can be valued in animal nutrition to solve the food gap in different areas. For that, a trial was conducted to evaluate the effects of partial or total replacement of oat hay by distilled rosemary residues (RR) on lamb’s growth, digestibility and nitro- gen balance. The experiment was carried on 28 Queue Fine de l’Ouest (QFO) male lambs (4 months old) with an average body weight (BW) of 15.2 + 0.16 kg, divided into 4 homogeneous groups (C, RR30, RR70 and RR100) ac- cording to their initial BW. All lambs were fed 500 g of concentrate and different amounts of hay and RR according to different substitution rates of 0, 30, 70 and 100 % respectively for C, RR30, RR70 and RR100. The average of total dry matter intake was 884 vs. 902 g/lamb/day for C and the experimental groups, respectively. The final BW of lambs receiving RR was numerically higher for RR30 and RR70 than C and RR100 but without significant difference. Con- sequently, the average daily gain was similar among groups. The digestibility of dry matter and organic matter were significantly higher for C compared to experimental ones (p < 0.05). However, the digestibility of crude protein was higher for C, RR30 and RR70 than that of RR100 group. The urinary and fecal nitrogen losses were unaffected by the diets. However, the nitrogen intake was improved for RR30 and RR70 than C and RR100. The nitrogen balance was positive for all groups. It was significantly higher for C, RR30 and RR70 than RR100 (6.1, 6.9 and 6.4 vs. 2.9, respec- tively). It was concluded that the oat hay substitution by RR did not alter the growth performance or the digestion but enhanced the nitrogen utilization of QFO lambs until the substitution rate of 70%.
Keywords: distilled rosemary residues; growth; digestibility; nitrogen balance; lambovi
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