Quantitative feed restriction rather than caloric restriction modulates the immune response of growing rabbits

Physiological and immunological aspects of feed restriction and its beneficial impacts in fattening rabbits' productivity-an updated review

Two feed restriction (FR) regimens are utilized with weaned rabbits including a quantitative FR (amount-limited feed or time-restricted admission to feed) and a qualitative FR (modulation of diet content especially protein and energy). The use of post-weaning FR may help in preventing post-weaning digestive disorders, stimulating compensating growth, improving feed efficiency, and decreasing carcass fat content. Interestingly, FR may contribute to changing meat's chemical composition and its physical quality attributes by regulating the morphological and biochemical characteristics of muscle fibers. Also, FR could enhance the gastrointestinal tract development, its histomorphology, and improve feed digestibility and absorption. Furthermore, FR regimens are involved in establishing gut microbial balance and enhancing the host immunological response. It might be concluded that post-weaning FR is involved in influencing the physiological and immunological aspects of growing rabbits. It might be documented that light to mild FR (i.e., 80-90% AL), early (i.e., at the first 2 weeks post-weaning), and relatively short in duration (i.e., for 2-3 weeks) had no negative effects on live body weight, while severing FR reduced live body weight in comparison with ad libitum rabbits.

Inclusion of Soybean Hulls (Glycine max) and Pupunha Peach Palm (Bactris gasipaes) Nanofibers in the Diet of Growing Rabbits: Effects on Zootechnical Performance and Intestinal Health

This study evaluated the inclusion of nanofibers from soybean hulls and pupunha peach palm heart sheaths in the diet of growing rabbits. Twenty-four New Zealand White rabbits (male and female) were allocated in three experimental groups: control, fed a basal diet; Nanosoy, fed a diet containing 7% soybean-hull nanofibers; and Nanopupunha, fed a diet containing 7% pupunha palm heart-sheath nanofibers. The Nanosoy-group rabbits showed poorer final weight, daily feed intake, and daily weight gain than those in other groups. In the duodenum, villus height, total mucosal thickness, and villus width were higher in rabbits that received nanofiber-supplemented diets than in the controls. Higher villus density and wall thickness were observed in Nanopupunha-fed rabbits than in the controls. In the jejunum, although the crypt depth was higher in Nanosoy-fed rabbits, the villus height:crypt depth ratio was higher in the Nanopupunha-fed group. Nanosoy-fed animals exhibited increased count Enterobacteriaceae populations. Rabbits in both nanofiber-fed groups exhibited higher lactic-acid bacterial counts than those in the control-diet group. Therefore, although the inclusion of 7% Nanopupunha in the diet of rabbits did not alter the performance, it improved intestinal health and increased the lactic-acid bacterial count in the cecum of growing rabbits.

Feed incorporation of dehydrated sainfoin: effects on health and performances of does and growing rabbits

The performance and health of does and growing rabbits were compared over three consecutive reproductive cycles for three groups of 20 nulliparous does and their litters (DS0, DS13, DS26) fed isonutritive feeds containing 0, 13 or 26% dehydrated sainfoin (DS, Perly cultivar). Feed intake, live weight and fertility of does were not affected by DS feed incorporation. The number of live kits at birth increased linearly with increasing DS incorporation (+1.5 from DS0 to DS26, P=0.042) and the stillborn rate tended to linearly decrease in groups fed DS (16.6 vs. 10.4%, P=0.086). Increasing the level of DS in feeds had no impact on the growth of the kits before weaning, but led to a linear reduction in the post-weaning growth rate (P<0.01, –2 for 26% DS), whereas the feed conversion ratio increased linearly with DS incorporation (P<0.01, 2.91 vs. 2.98, resp. for DS0 and DS26). No effect of DS feed incorporation was detectable on doe and kit mortality rates. Excretion of coccidia by both does and growing rabbits was not affected by DS incorporation. For 70 d old rabbits, the levels of immunoglobulins A and G and of white blood cells were not significantly different between groups and high levels of IgG (average: 8.1 mg/mL) were recorded, suggesting a coccidia infestation. Overall doe mortality remained under 5% and was not affected by the reproductive cycle (P=0.24). The stillborn rate decreased from 18 to 6%, (P<0.01) from cycle 1 to 2, and the number of live rabbits at birth increased from 8.0 to 10.7 (P<0.01). Kit mortality remained low before weaning (under 2.5%), and very low after weaning (<1%). Excretion of coccidia by does decreased from cycle 1 to cycle 3, whereas excretions by growing rabbits remained stable.

Effects of dietary manipulation on compensatory growth of juvenile genetically improved farmed tilapia (Oreochromis niloticus)

A 40-day feeding trial was conducted to investigate whether feeding a low-protein diet (25%) once daily for either 10 (L10H30) or 20 (L20H20) days then re-feeding a high-protein diet (35%) thrice daily elicit compensatory growth (CG) in genetically improved farmed tilapia (GIFT), Oreochromis niloticus (11.02 ± 0.05 g). Fish on the control treatment were fed 35% protein diet over 40 days (H40). Fish were stocked into nine 100-L tanks (30 fish per tank) with 3 replicate tanks for each group. Growth performance, feed utilization, proximate composition of body compartment, serum biochemical parameters, and hepatopancreatic histology and expressions of some genes related to inflammatory cytokine were evaluated every 10 days. Growth of L10H30 fish were similar to the control, whereas the weight of L20H20 fish were lower (P < 0.05) at day 20, but this significant difference disappeared at the end of the experiment. During 20-30 days, specific growth rate and feed intake were significantly higher (P < 0.05) and feed efficiency was lower (P < 0.05) in L20H20 fish than those in H40 fish. Dietary manipulations did not affect (P > 0.05) viscerosomatic and hepatosomatic indices, condition factors, serum biochemical parameters, and hepatopancreatic histology. Significant differences (P < 0.05) in proximate composition were observed only in viscera and muscle between L20H20 fish and H40 fish at day 20. The mRNA expressions of heat shock protein 70 kDa, tumor necrosis factor-α and interleukin (IL)-1β were higher (P < 0.05) in L10H30 and L20H20 fish at day 10, while IL-1β mRNA expression was lower (P < 0.05) in L20H20 fish at day 30 than those in H40 fish. Our results indicated that L20H20 fish elicited a complete CG and induced reversible physiological variations in juvenile GIFT.

Effects of incorporating agro-industrial by-products into diet of New Zealand rabbits: Case of rebus of date and apricot kernel meal

Aim

The aim of this study was to determine the effects of incorporating the by-products complex of date and apricot on the fattening performance of the New Zealand breed of rabbits, to reduce the economic costs of the food formula.

Materials and Methods

A total of 288 young New Zealand rabbits aged 35 days were divided into four equal groups each containing 72 animals and into sub-groups of 6 rabbits per cage, depending on the rate of substitution of corn by date rebus and of soybean meal by apricot kernel meal (0%, 10%, 20%, and 30%).

Results

The change in weight from day 35 to 77 and the average daily gain are not significantly different, regardless of the diet. The pH and water content are proportional to the substitution rates (6.4-6.6% and 66.5-68.8%). Meat protein levels increased significantly, in particular for the 10% and 30% groups (+8.1% and 6%) while the fat and mineral content levels decreased significantly, in particular for the 30% group displaying -16% and -17%, respectively. Incorporation of dates and apricot kernel meal into the ration of rabbits reduces the cost of the kilogram of food produced of -9%, with an opportunity cost of 165 Algerian dinars (DZD).

Conclusion

The date rebus/apricot kernel meal complex can be used as an alternative to the corn/soybean meal complex at substitution rates of up to 30% without adverse effects on growth rates, feed contribution, or slaughter yield. It improves the chemical composition of the meat and reduces the cost price of the quintal of feed produced.

Effect of feed restriction and different crude protein sources on the performance, health status and carcass traits of growing rabbits

<p>We evaluate the effect of the crude protein source (CP) in combination with 2 feeding strategies (AL: ad libitum or R: restricted) on the performance, health status and carcass traits of growing-fattening rabbits (between 33 and 75 d of age). Two experimental diets were formulated; the first containing soybean meal (SBM: 70 g/kg) as the main CP source and the second containing white lupin seeds (WLS: 105 g/kg) as the main CP source. A total of 160 weaned Hyplus rabbits (774±10 g live weight) were randomly allocated to the experimental groups, combination of feeding strategy and diet (AL SBM, R SBM, AL WLS and R WLS; 40 rabbits per group with 4 rabbits per cage), for 42 d. The feeding programme was applied as follows: both the AL SBM and AL WLS rabbits were fed ad libitum for the entire fattening period, whereas the R SBM and R WLS rabbits were subjected to feed restriction between 33 and 47 d of age (75% of the ad libitum intake). Afterwards, all restricted rabbits were fed ad libitum until 75 d of age. Regardless of the CP source, the feed restriction reduced the final live weight by 83 g, chilled carcass weight by 65 g, and dressing out percentage by 0.9 percentage points (P&lt;0.05). There was a higher chilled carcass weight (+114 g; P=0.001) and reference carcass weight (+91 g; P=0.001) in rabbits fed with WLS diet than in rabbits fed with SBM diet. No dead or morbid rabbits were observed in restricted rabbits during the restriction period. There was no effect of the diet on the health of rabbits. However when the rabbits of AL SBM and AL WLS group were compared did we observe a lower number of rabbits at sanitary risk in AL WLS group (2 vs. 12 rabbits, P=0.006). In conclusion, the growth performance was not affected by the crude protein source, and no interaction between dietary CP source and feeding regime was observed. Feed restriction regime did not improve sanitary risk index throughout the entire period.</p>