Application of bioelectrical impedance analysis to assess rabbit's body composition from 25 to 77 days of age.

The aim of the study was to develop prediction equations for assessing, in vivo, the whole body composition of growing rabbits. The accuracy of the models obtained was externally validated with independent data sets. One hundred fifty rabbits grouped at 5 different ages (25, 35, 49, 63, and 77 d) were used. A body composition analyzer with 4 terminals was used to obtain resistance (Rs; Ω) and reactance (Xc; Ω) values. The distance between internal electrodes (D; cm), body length (Len; cm), and live BW (g) were also registered. Average values of Rs, Xc, impedance (Z), Len, D, and BW were 83.5 ± 23.1 Ω, 18.2 ± 3.8 Ω, 85.6 ± 22.9 Ω, 30.6 ± 6.9 cm, 10.8 ± 3.1 cm, and 1,454 ± 845 g, respectively. At each selected age, animals were slaughtered, ground, and frozen (-20°C) for determining water, fat, CP, ash, and GE (70.5 ± 3.36%, 27.7 ± 7.61% DM, 54.9 ± 5.41% DM, 11.1 ± 1.55% DM, and 2,267 ± 183 kJ/100 g DM, on average, respectively). Fat and GE contents increased with the age, whereas CP, ash, and water contents decreased. A multiple linear regression analysis was used to determine the prediction equations, using BW, Len, and Z data as independent variables. Equations obtained to estimate water (g), CP (g), fat (g), ash (g), and GE (MJ) had coefficient of determination () values of 0.99, 0.99, 0.97, 0.98, and 0.99, respectively, and the relative mean prediction error (RMPE) was 2.79, 6.15, 24.3, 15.2, and 10.6%, respectively. When water was expressed as a percentage, the and RMPE were 0.85 and 2.30%, respectively. When prediction of the content of protein (% DM), fat (% DM), ash (% DM), and energy (kJ/100 g DM) was done, values of 0.79, 0.83, 0.71, and 0.86, respectively, for and 5.04, 18.9, 12.0, and 3.19%, respectively, for RMPE were obtained. It could be concluded that bioelectrical impedance analysis is a good, noninvasive method to estimate, in vivo, whole body composition of growing rabbits from 25 to 77 d of age.

Effect of type of grinding of barley and dehydrated alfalfa on performance, digestion, and crude mucin ileal concentration in growing rabbits.

The effects of type of grinding of barley and dehydrated alfalfa (DA) were tested in rabbits weaned at 35 d of age with an average BW of 846 ± 93 g. Four nonmedicated diets were arranged in a 2 × 2 factorial structure, with type of grinding (coarse grinding with a 4.5-mm screen or fine grinding with a 1.5-mm screen) of barley (TGB) and DA (TGDA) as the main factors. A total of 1,056 mixed-sex rabbits (264 per diet) were fattened until d 63. Most of these rabbits (216 per diet) were housed in pairs and were used only to record mortality rate. Mortality was also recorded for the remaining 192 rabbits, which were housed individually and used to determine growth performance. From this group, 100 rabbits were used to determine digestive traits. Apart from those rabbits, a different group of 88 rabbits (44 housed individually and the remaining 44 housed in pairs) was used in the digestibility trial. All rabbits in this group were used to determine ileal digestibility (13 pools of ileal digesta per diet) and ileal mucin concentration (6 pools of ileal digesta per diet), whereas only the 44 individually housed rabbits were used to assess the fecal digestibility coefficients (11 rabbits per diet). Last, a jejunal sample was excised from 32 of the 44 individually housed rabbits to determine mucosal histology. Treatments did not affect ADG, ADFI, or G:F in the entire fattening period, but in the 49- to 63-d period, the diet containing both finely ground barley and DA reduced ADFI (P=0.08) compared with the other treatments (130 vs. 137 g). Moreover, this diet increased total digestive tract (4.76%, P=0.08) and cecal content (11.3%, P=0.08) weights compared with the other 3 treatments. Pylorus (P=0.09) and mixed digesta (P=0.06) pH, respectively, were reduced from 1.53 and 1.59 to 1.37 and 1.44 when both barley and DA were finely instead of coarsely ground. Grinding both barley and DA coarsely reduced the ileal digestibility of starch (0.899 vs. 0.936, P=0.06), increased (P < 0.01) its ileal flow and content in the feces to 1.66 g/d and 7.42 g/kg of DM, respectively, and led to decreased fecal digestibility (0.932 vs. 0.951, P < 0.01) compared with fine grinding. Coarse DA shortened villi (612 vs. 704 µm, P=0.02), increased crypt depth (121 vs. 92.1 µm, P=0.01), and reduced the villus:crypt ratio (5.08 vs. 7.66, P < 0.01) compared with finely ground DA. Furthermore, the greatest ileal crude mucin (148 vs. 107 g/kg of DMI, P=0.02) and sialic acid (71.7 vs. 61.7 mg/kg of DMI, P=0.04) concentrations were reported in rabbits receiving the diet with both coarsely ground barley and DA. Finally, mortality rate was not influenced by treatments, with an average of 9.64%. In conclusion, the diet containing finely ground barley and coarsely ground DA did not increase the weight of cecal contents, resulting in increased feed intake and leading to increased ileal digestibility and reduced ileal flow of starch.

Follicular, oocyte and embryo features related to metabolic status in primiparous lactating does fed with high-fibre rearing diets.

Fertility of primiparous lactating does in the early postpartum (pp) period is very low mainly due to pronounced deficient energy intake, influencing oocyte and embryo developmental competence. The hypothesis used in this work was that high-lignin fibre diet supplied during the rearing period could increase feed intake and, consequently, improve the reproductive physiology and metabolic status of primiparous does in the early pp period. Diets with high-lignin [HL: 15.8% dry matter (DM)] or standard-lignin content (SL: 4.9% DM) were supplied until parturition time. No diet effects in serum oestradiol, progesterone concentrations and follicle categories were found in the histological study. Metaphase II rate of in vitro-matured oocytes was significantly higher in the SL vs the HL group (p < 0.001). Cytoplasmically degenerated oocytes (in terms of abnormal distribution of cortical granules) and follicular atresia rate were significantly lower in the SL group than in the HL group (p < 0.05 and p < 0.005 respectively). In addition, HL-fed does showed lower number of viable embryos and higher rate of retarded in vivo-recovered embryos compared with the SL group (p < 0.05). Neither in vitro embryo development of viable embryos nor conception rate was significantly different between groups. Feed intake increased during the first pregnancy in the HL group (p < 0.05), but not during early lactation. Serum protein, non-esterified fatty acid and leptin concentrations, as well as estimated body composition were similar in does fed with both diets. In conclusion, the enhancement of reproductive management by using highly lignified products in rearing diets does not seem to report physiological reproductive benefits affecting oocyte maturation rate and embryo viability in primiparous lactating does.

Effect of substitution of a soybean hull and grape seed meal mixture for traditional fiber sources on digestion and performance of growing rabbits and lactating does.

The aim of this work was to determine what concentration of a mixture of soybean hulls and defatted grape seed meal (SHDG) could be included in diets that meet or exceed ADL and particle size requirements for rabbits. Four isonitrogenous and isofibrous pelleted diets were formulated, with similar ADL concentration and particle size (18.3% CP, 42.6% NDF, 7.1% ADL, and 34.9% of particles larger than 0.315 mm, on a DM basis). Diets contained a constant ratio of soybean hulls:defatted grape seed meal (81:19) provided at 0, 13.3, 26.7, or 40% SHDG, which was substituted for a 35:35:30 mixture of alfalfa hay, sunflower hulls, and wheat straw. Thirty-six rabbits were used to determine nutrient digestibility and cecotrophy traits. A feeding trial was carried out using 160 weanling rabbits (30 d of age; 536 +/- 7.1 g). Milk production was measured in 56 rabbit does. Increasing concentrations of SHDG in the diet did not affect digestibilities of DM, GE, or NDF or DE that were on average 54.7, 55.2, and 21.6% and 10.2 MJ/kg of DM, respectively. Digestibility of CP decreased in diets containing 40% (P = 0.002) and 26.7% (P = 0.054) SHDG compared with diets containing a lower percent of SHDG. Daily recycling of CP through cecotrophy, an indicator of microbial protein production, was not affected by SHDG inclusion. Growing rabbits fed 40% SHDG had reduced ADFI and ADG compared with rabbits fed 26.7% SHDG or less (106 vs. 113, 111, or 111 g/d, and 35.8 vs. 37.8, 36.6, or 37.6 g/d, respectively). There was no effect on G:F from adding SHDG to the diets. In the 2-wk period after weaning, ADG decreased (P = 0.031) for rabbits fed 40% SHDG compared with rabbits fed 26.7% SHDG or less (28.4 vs. 32.2, 30.8, of 32.2 g/d), with no effect on ADFI or G:F. Type of diet did not influence mortality during the fattening period, which averaged 6.25%. Rabbit does fed 40% SHDG had reduced ADFI (411 vs. 430 g/d; P = 0.023) compared with rabbits fed 26.7% SHDG or less, with no effect (P > 0.11) on milk production, weight of the litter at 21 d and at weaning (30 d), or parturition-effective mating interval. In conclusion, SHDG can be included up to 26.7% in diets for fattening rabbits and lactating does that meet ADL and particle size requirements.

Effect of inclusion of defatted grape seed meal in the diet on digestion and performance of growing rabbits.

The digestion and nutritive value of defatted grape seed meal (DGSM) was investigated. A basal diet was formulated to meet requirements of growing rabbits. Another diet was formulated by substituting 15.2% of the basal diet with DGSM. Two hundred eight weaned 30-d-old rabbits were fed these diets, and fattening performance was recorded. Eighty animals were used to study the effect of DGSM inclusion on cecal fermentation traits and intestinal disaccharidase activity at two ages (5 and 35 d after weaning). Fecal apparent digestibility of nutrients was measured in 18 rabbits. A third diet was formulated to contain DGSM (61.3%) as the sole source of fiber and a supplement consisting of wheat flour, casein, lard, and a mixture of vitamins and minerals to avoid nutrient imbalances. This semipurified diet was used to determine cecal digestion traits, disaccharidase activity in the small intestine, fecal apparent digestibility of nutrients, and rate of passage in 70-d-old rabbits. Digestible energy and NDF and CP digestibilities of DGSM calculated by difference were 5.51 +/- 0.89 MJ/kg DM, 24.5 +/- 5.76%, and 46.8 +/- 14.9%, respectively. Inclusion of 15% of DGSM in the basal diet increased ADFI in finishing rabbits (from 9 to 15%; P < 0.05), so that DE intake increased although dietary DE concentration decreased. As a consequence, ADG increased by 3.3% in the whole fattening period (P = 0.046). The increase in ADFI was parallel to an 8% decrease in the weight of cecal contents (P = 0.059), and it was in agreement with the relatively short cecal mean retention time of DGSM (7.61 h) in the semipurified diet. Inclusion of 15% of DGSM in the basal diet did not affect (P > or = 0.20) mortality (10.1%) or cecal concentrations of VFA, NH3 N, or cecal pH either at 5 d (71.9 mM, 17.7 mM, and 5.75, respectively) or at 35 d after weaning (74.6 mM, 10.1 mM, and 5.66, respectively) but improved the sucrase activity in the ileum by 36% (P = 0.031). Digestibility of NDF of DGSM in the semipurified diet was 8.57%, which agrees with the low acidity and weight of cecal contents of animals fed this diet (6.26 and 3.63% BW, respectively). From these results, we conclude that DGSM has a relatively high DE concentration and its inclusion at moderate levels (15%) in the diet exerts a positive effect on ADFI, DE intake, and ADG with no impairment of cecal fermentation and mortality.

Effect of substitution of starch for fiber and fat in isoenergetic diets on nutrient digestibility and reproductive performance of rabbits.

The optimal level of starch in diets for rabbit does was investigated. Five isoenergetic and isoproteic diets containing 26.6, 24.6, 19.0, 16.8, or 13.0% starch and 31.2, 33.4, 36.0, or 41.2% NDF, respectively (DM basis), were made by substitution of starch for NDF and fat. The effect of diet on nutrient digestibility was determined in fattening and nonlactating and lactating adult does using a total of 105 rabbits. Increasing dietary starch content linearly increased (P < .001) DM, GE, CP (P = .07), and starch digestibilities but decreased (P < .001) NDF digestibility. Nutrient digestibility was higher (P < .05), except for CP, in adult does than in fattening rabbits. Dry matter and GE digestibilities were higher (P = .08) for nonlactating than for lactating does. A lactation trial using 440 rabbit does was conducted over a 6-mo experimental period. Milk production and milk composition were measured in 70 lactations. A decrease in dietary starch content did not improve pup mortality before weaning but impaired (linear, P < .001) dry feed intake and pup growth from 21 d until weaning. Diet did not influence does' feed intake, milk DM, ether extract, and CP contents or prolificacy. However, diet had quadratic effects on milk production (P = .15), milk lactose content (P = .07), parturition interval (P = .02), and feed conversion efficiency (P = .02), expressed both per weight or number of pups weaned. Optimal values were reached for dietary starch and NDF contents at approximately 20 and 35.5% (DM basis), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)