Effect of Mash Feed on the Performance of Growing Rabbits

Some feed mill industries adapt the physical presentation of their feeds to farmers' expectations in term of transparency and costs: mash presentation ("crude" raw materials) in ruminant, mixture of cereals for poultry, etc. It thus seems important to check if a different presentation from the pellet could be used for the rabbit feeding. More especially as many industrial tools exist and can mix crude raw materials with or without incorporation of long fibre and/or liquids. Respect to feed presentation, the literature explains the influence of the crushing of the raw materials on the performances by comparing the same feed presented as pellet or coarsely crushed. Other authors demonstrated the interest of the pelleted form compared to the flour presentation on rabbit feed intake, growth and feed conversion (Candau et al., 1986; Harris et al., 1983; Fomunyam et al., 2000; Kpodekon et al., 1998). A first study (Rochon and Goby, 1986) showed a deterioration of the growth and feed conversion with diets based on raw materials crushed or not, respect to pelleted diets, but with different nutritional levels between diets. In another work (Goby and Rochon, 1990), with diets having a similar nutritional value (pellet vs. crude raw materials in grains and flour), the authors did not observe differences on rabbit performance.

From these elements, it seems useful to study the absence of flour and a maximum level of crude raw materials, while keeping the same nutritional level. This was the aim of our study, in which the percentage of "mash" was limited to 25% of the diet. 

The test was carried out at the experimental station of Saint Symphorien (72, France) during the summer period. A total of 672 young rabbits (Hyplus), weaned at 32 d of age, were divided into 4 homogeneous batches. Each batch was composed of 24 cages with 7 young rabbits (the allocation was done according to the individual weight at weaning and weight of the litter). Animals were controlled from 32 to 70 d of age. The four diets were formulated to have the same nutritional values, by combining a pelleted part and a "mash" part in variable percentages (Table 1). Diet 1 was a 100% pelleted feed A (control), while the other diets (Diet 2, Diet 3 and Diet 4) presented a pelleted part (85, 80 and 75% pelleted feed B, C and D, respectively) and a "mash" part (15, 20 and 25%, respectively, constituted of different raw materials). Diets 1 and 3 are presented in pictures (picture 1).

Table 1: Theoretical values of the experimental diets (feed + mash)

Table 2: Composition of the pelleted feeds (%)

The crude raw materials were selected according to their physical characteristic and their capability to be eaten such as they are (size, hardness).

Picture 1: Diet 1 and diet 3 pictures.

The four pelleted feeds (Table 2) were formulated to have isonutritive diets (pelleted feed + mash). No antibiotics or coccidiostatics were used in feed or water during the test. The animals were restricted to 85% of the theoretical ad libitum intake (for a feed with 2350 kcal of digestible energy per kg) up to 56 days, and then they were fed ad libitum. 

The rabbits were weighed collectively by cage at 32, 43, 56 and 70 days of age. The feed consumption was also measured by cage for the periods 32-43, 43-56 and 56-70 days. Control of wasting (the feed not consumed, which were still in feeding dishes) and scraping (the feed thrown in pits) was also done. Mortality was recorded daily. A control of hardness and durability of the pelleted feed was carried out. 

Data of growth, feed consumption and feed conversion ratio were subjected to variance analysis including the diet as a fixed effect and the weaning weight as a covariate, according to a GLM procedure with the software SPSS. The differences between diets were analyzed with Sidak-test 5%. Mortality was analyzed by χ²-test. 

The chemical analysis (moisture, protein and crude fibre) of feed A to D were in conformity with the expected values. The variations of hardness and durability were minor between the different feeds: 1.7 points for hardness and 1.9 points for durability (Table 3)

Table 3: Chemical analyses of the diets and physical analyses of the pelleted feed

The trial was performed under good sanitary conditions: mortality in each experimental group was low (between 0.6 and 1.8%) and the differences were not significant (table 4). During the restricted period (32-56d), the weight gain averaged 45.8 g/d and was significantly different with 48.1, 46.0, 45.1 and 43.9 g/d respectively for diets 1, 2, 3 and 4 (table 4). During the ad libitum period, the differences were not significant. For the whole period (32-70d), the weight gain decreased significantly with the increase of the mash percentage inclusion (47.9, 47.1, 46.4 and 45.5 g/d for diets 1, 2, 3 and 4, respectively). And also, residual variability of weight gain was lower during the restricted period (coefficient of variation from 2.3 to 2.8%) than during the ad libitum period (from 6.8 to 11.6%).

Table 4: Growth performances and intake according to the percentage of mash in the diet

As expected, feed intake during the restricted period was the same for the different groups. But, it seems that feed intake during both the ad libitum and the whole period was higher for "mash" diets (2, 3 and 4) than for "all pelleted" diet (1). A weak wasting was observed on diets 3 and 4 starting from the ad libitum feeding: 5 cages in diet 3 and 9 cages in diet 4. This wasting was also weak in quantity: for diet 3, an average of 204 g/cage during the ad libitum period which represent 2.1 g/d/rabbit, and for the diet 4, 161 g/cage or 1.6 g/d/rabbit. This wasting did not deteriorate the feed intake compared to diet 2.

The feed conversion ratio was significantly different between diets during the restricted period but not during the ad libitum period. On the whole period, the differences were significant: 2.75, 2.87, 2.90 and 2.96 g/g for the diets 1, 2, 3 and 4, respectively.

During the restricted period, the animals consumed all the food distributed, whatever the presentation, and without wasting. Feed efficiency was better with the diet 1, certainly because the animal valued more the pellets than the mash mixture (although the diets had the same nutritional value and intake). When fed ad libitum with a mash presentation, the animal increased its ingestion whatever the percentage of mash. The rabbit has a different behaviour according to the physical presentation of the diet, as it is shown in trials comparing pellets versus flour (Lebas, 1973). In this trial, the raw materials were also pelleted, the hypothesis could be a different efficiency according to pellet size, hardness or palatability of raw materials. During the ad libitum period, the feed efficiency was still better with pelleted feed (lower intake for a similar growth). These results agreed with Çaliskaner et al. (1996), where a pelleted form was compared to the same diet with fresh alfalfa added. In a general way, feed efficiency was always better for the pellets, and several explanations could be advanced: the pelleted feed could have a better digestibility because of crushing of the constitutive raw materials, which will decrease the size of the particles. The rabbit may also have a selective intake behaviour when a mash mixture diet is provided which could induce a modification of the nutrient intake. However, these are suppositions, since no observation of the ingestion behaviour was performed in the present study. 

In conclusion, the whole pellet presentation of the diet lead to the better performance of growing rabbits, compared with the use of a percentage of the diet in mash presentation, particularly with respect to feed efficiency. 

Çaliskaner S., Akin Y., ÇiftÇi I., Gunal M. 1996. A research on the use of mash and pelleted feeds with fresh alfalfa in rabbits diets. Tr. J. Vet. Anim. Sci., 20, 27-32.

Candau M., Auvergne A., Comes F., Bouillier-Oudot M. 1986. Influence de la forme de présentation et de la finesse de mouture de l'aliment sur les performances zootechniques et la fonction caecale chez le lapin en croissance. Ann. Zootech., 35, 373-386.

Fomunyam R.T., Ndoping B.N. 2000. Utilization of pelleted and non pelleted feed by growing rabbits in tropical conditions. World Rabbit Sci., 8, 61-62.

Goby J.P., Rochon J.J. 1990. Utilisation d'un aliment fermier chez le lapin à l'engraissement: digestibilité et impact du tri alimentaire. 5èmes Journées de la Recherche Cunicole, comm. n°62, ITAVI publ, Paris, France.

Harris D.J, Cheeke P.R., Patton N.M. 1983. Feed preference and growth performance of rabbits fed pelleted versus unpelleted diets. J. Appl. Rabbit Res., 6, 15-17.

Kpodekon M., Lebas F., Djago A.Y., Coudert P. 1998. Relative efficiency of local meal concentrate and pelleted feed for fattening rabbits in tropical conditions. Interaction with rabbit's origin. World Rabbit Sci., 6, 291-297.

Lebas F. 1973. Possibilités d'alimentation du lapin en croissance avec des régimes présentés sous forme de farine. Ann. Zootech., 22, 249-251.

Rochon J.J., Goby J.P. 1986. Utilisation d'aliments fermiers pour l'engraissement de lapins. 4èmes journées de la recherche cunicole, comm. n°12, ITAVI publ, Paris, France.