Replacement of berseem hay by Salix tetrasperma on physiological performance of New Zealand White rabbits under subtropical conditions of Egypt

Paulownia Leaves as A New Feed Resource: Chemical Composition and Effects on Growth, Carcasses, Digestibility, Blood Biochemistry, and Intestinal Bacterial Populations of Growing Rabbits

Simple Summary

Paulownia trees are grown as a woody biofuel crop, and they yield large amounts of leafy biomass rich in nitrogen. However, there is limited information on the use of paulownia leaves as an animal feed resource. Hence, this study was conducted to assess the effects of paulownia leaf meal (0%, 15%, and 30% in diets) on the growth performance, nutrient digestibility, blood biochemistry, and intestinal microbiota of growing rabbits. The chemical analyses of paulownia leaves indicated that most of the nutrients are similar to those in alfalfa hay. The in vivo results showed that the use of up to 15% paulownia leaf meal instead of alfalfa hay in the diets of the rabbits did not have any negative effects on their performance, nutrient digestibility, and blood constituents. In addition, a notable reduction in both cecal and feed pathogenic bacteria was observed when paulownia leaf meal was included in the diets.

Abstract

This experiment was conducted to study the effects of paulownia leaf meal (PLM) as a nontraditional feed on the growth, carcasses, digestibility, blood chemistry, and intestinal microbiota of growing rabbits. Sixty rabbits (5-weeks old) were randomly allotted to three dietary treatments containing three amounts of PLM (0%, 15%, and 30%). The results showed that PLM has a higher content of ether extract, organic matter, methionine, tyrosine, histidine, manganese, and zinc than alfalfa hay. Body weight gain decreased when 30% PLM was provided. The best feed conversion ratio was recorded in the rabbits fed 15% PLM. A notable increase in high-density lipoprotein levels with a significant decrease in low-density lipoprotein was noted in the rabbits fed the PLM diets. Total fungi and Enterobacteriaceae and total bacterial count in the feed were significantly reduced because of PLM. In the cecum, coliforms, Enterobacteriaceae species, and total bacterial count declined in the rabbits fed the PLM diets. Conclusively, up to 15% PLM can be used in rabbit diets without any deleterious effects on the performance, nutrient digestibility, and blood constituents. In addition, dietary inclusion of PLM has the potential to reduce cecal pathogenic bacteria in rabbits.

Digestion, growth performance and caecal fermentation in growing rabbits fed diets containing foliage of browse trees

<p>This study aimed to evaluate the effect of feeding dried foliage (leaves and petioles) of <em>Acacia saligna</em>, <em>Leucaena leucocephala</em> or <em>Moringa oleifera</em> on the performance, digestibility, N utilisation, caecal fermentation and microbial profiles in New Zealand White (NZW) rabbits. One hundred weaned male NZW rabbits weighing 819.2±16.6 g and aged 35±1 d were randomly allocated into 4 groups of 25 rabbits each. Rabbits were fed on pelleted diets containing 70% concentrate mixture and 30% Egyptian berseem (<em>Trifolium alexandrinum</em>) hay (Control diet) or one of the other 3 experimental diets, where 50% of berseem hay was replaced with <em>A. saligna</em> (AS), <em>L. leucocephala</em> (LL) or <em>M. oleifera</em> (MO). Compared to Control diet, decreases in dry matter (DM; <em>P</em>=0.004), organic matter (<em>P</em>=0.028), crude protein (CP; <em>P</em>=0.001), neutral detergent fibre (<em>P</em>=0.033) and acid detergent fibre (<em>P</em>=0.011) digestibility were observed with the AS diet. However, DM and CP digestibility were increased by 3% with the MO diet, and N utilisation was decreased (<em>P</em>&lt;0.05) with AS. Rabbits fed AS and LL diets showed decreased (<em>P</em>=0.001) average daily gain by 39 and 7%, respectively vs. Control. Feed conversion was similar in Control and MO rabbits, whereas rabbits fed AS diet ate up to 45% more feed (<em>P</em>=0.002) than Control rabbits to gain one kg of body weight. Caecal ammonia-N was increased (<em>P</em>=0.002) with LL, while acetic acid was decreased (<em>P</em>=0.001) with AS diet vs. other treatments. Caecal <em>E. coli</em> and <em>Lactobacillus</em> spp. bacteria counts were decreased with MO by about 44 and 51%, respectively, vs. Control. In conclusion, under the study conditions, tree foliage from <em>M. oleifera</em> and <em>L. leucocephala</em> are suitable fibrous ingredients to be included up to 150 g/kg in the diets of growing rabbits, and can safely replace 50% of berseem hay in diets of NZW rabbits without any adverse effect on their growth performance. Foliage from <em>M. oleifera </em>had a better potential as a feed for rabbits than that from <em>L. leucocephala</em>. Although foliage from <em>A. saliga </em>may be also used at 150 g/kg in the diets of growing rabbits, this level of inclusion may result in reduced feed digestibility and growth performance.</p>