J Fernández-Carmona

Prediction of the energy value of rabbit feeds varying widely in fibre content

Abstract Digestibility trials of 23 pelleted diets, with one or two ingredients and having 8.7–53.5% acid detergent fibre (ADF) on a dry matter (DM) basis, were carried out in adult rabbits fed ad libitum. Using a step-wise linear regression approach, the relationship between the digestible energy content (DE) or the coefficient of digestibility of gross energy (dGE) and the chemical composition of diets was established. Excluding beet pulp, with a very high crude fibre digestibility (54.8%), the prediction equations obtained were: DE (MJ kg −1 DM) = 14.2 − 0.205 ADF + 0.218 EE + 0.057 CP ( R 2 = 0.965, RSD = 0.494) and dGE (%) = 83.2 − 1.07 ADF ( R 2 = 0.951, RSD = 3.15) where ADF, ether extract (EE) and crude protein (CP) are expressed as a percentage on a DM basis. When diets with level of EE or CP higher than 6% or 18% respectively (grape marc, olive oil cake, brewers grains, sunflower meal) were also removed, the prediction equations became: DE = 15.9 − 0.219 ADF ( R 2 = 0.974, RSD = 0.391) and dGE = 85.6 − 1.20 ADF ( R 2 = 0.977, RSD = 2.02). The contents in DE, digestible crude protein and undigestible crude fibre of 21 ingredients are presented and discussed in comparison with other studies.

Effect of high fat diets on the performance and food intake of primiparous and multiparous rabbit does

The influence of high fat diets on several production traits of primiparous and multiparous rabbit does was studied in 246 lactations from a total of 61 crossbreed rabbit does (Californian × New Zealand). Starting with a control diet (diet C) with 26 g ether extract (EE) per kg dry matter (DM), two isoenergetic diets were formulated adding fat from vegetable sources up to 99 g EE per kg DM (diet V) or animal sources up to 117 g EE per kg DM (diet A). Digestible energy/digestible protein ratio (DE/DP) was maintained between 82 and 87 kj/g. Food intake decreased with high fat diets compared with the control diet during gestation (P ‘lt; 0·001), which implied a decrease in the DE intake ( P P 0·75 for C, V and A diets, respectively) but increased the DE intake (1121 kj/day per kg M° 0·75 for C diet cf. 1325 for V and 1264 for A diets; P 0·05). However, multiparous does on C diet showed a greater food intake during the last 2 weeks of lactation (110·6 for C diet v. 101·5 and 98·9 g DM per day per kg M 0·75 for V and A diets, respectively; P P P P P P P

Effect of diet composition on the production of rabbit breeding does housed in a traditional building and at 30°C

Fifty-seven crossbreed New Zealand White rabbit does were maintained in a traditional building (TB) or at a constant temperature of 30°C, and fed ad libitum on two diets with about 11.2 MJ digestible energy (DE) kg−1 dry matter (DM) and 121 g (Diet 1) or 193 g (Diet 2) crude fibre kg−1 DM. Records from 162 lactations were examined, using litter size as a covariate. Feed intake of the two diets was similar for the first 3 weeks of lactation, but litter mortality was higher (21.0 vs. 15.5%, P < 0.05) and litter liveweight gain lower (1.47 vs. 1.66 kg, P < 0.01) with Diet 2. The effect of the diets for the last 2 weeks of lactation was different in the TB from that at 30°C. DE intake of Diet 2 was higher in the TB (1480 vs. 1310 kJ kg−0.75 day−1, P < 0.001), but milk production and litter liveweight gain were similar. At 30°C, DE intake of both diets was similar, but milk production (98 vs. 112 g day−1, P < 0.05) and litter liveweight gain (2.11 vs. 2.36 kg, P = 0.093) were lower with Diet 2. Feed intake and performance of does and litters were reduced in the 30°C environment.

Nutritive value of coarse and fine wheat brans for rabbits

The objective of this study was to compare the nutritive value of two wheat brans obtained at different stages of milling, described commercially as coarse and fine wheat bran. Digestibility trials of four samples of coarse and four of fine wheat bran from four commercial Spanish firms were carried out in 90 New Zealand White Californian rabbits fed ad libitum. Fine brans were characterised by a higher content of particles of less than 1 mm, while coarse brans had a higher content of particles greater than 2 mm. There was no significant differences in the chemical composition of the brans, but fine brans showed, on average, a significantly higher OP < 0:05U content of crude protein bound to acid-detergent fibre (2.94 vs. 1.90 g CP‐ADF kg ˇ1 dry matter). The digestibility of the chemical components did not vary widely except for crude fibre and crude protein (CP) which were, on average, significantly higher in coarse than fine bran. Animals on coarse bran consumed more feed (126.2 g/day) than those on fine bran (111.7 g/day). The best single predictor of digestible energy (DE) and gross energy digestibility (dGE) was ADF (R 2 =R 2 a 0:81 and 0:79, respectively; P < 0:001). A significant improvement in the accuracy of prediction was obtained when CP‐ADF OP < 0:01U was introduced into the model (R 2 =R 2 a 0:88 and 0:89 for DE and dGE, respectively). The best prediction for crude protein digestibility (dCP) was obtained by the inclusion in the model of both ADF and CP‐ADF (R 2 =R 2 a 0:64; P < 0:001). For digestible protein, the best single predictor was acid-detergent lignin (R 2 =R 2 a 0:63; P < 0:001), although accuracy of digestible protein prediction was improved with crude protein and CP‐ADF as independent variables (R 2 =R 2 a 0:69; P < 0:001). Results suggest that the classification of wheat bran into coarse and fine brans is difficult to justify from their chemical composition and that their nutritive value seem to be related to the digestibility of its fibrous or protein fractions and less to other nutritive components. # 2000 Elsevier Science B.V. All rights reserved.