Effects of animal type (wild vs. domestic) and diet alfalfa level on intake and digestibility of European adult rabbits (Oryctolagus cuniculus).

The aim of this study was to evaluate the effect of the level of alfalfa in the diet on feed intake and digestibility of two types of rabbits, wild (Oryctolagus cuniculus algirus) vs. domestic (O. cuniculus cuniculus). Ten wild (W; mean LW = 927 g) and 10 domestic (D; mean LW = 4,645 g) adult rabbit does were fed ad libitum two pelleted diets: a control diet (C) with 15% of dehydrated alfalfa hay (as feed basis) and a test diet (A) with 36% of dehydrated alfalfa hay (as feed basis), according to a change-over design. Wild does dry matter (DM) intake per kg live weight (BW) was 55% higher (p < .001) than the intake of the D ones (58 g vs. 37 g DM per kg BW respectively). However, no difference (p > .05) was found when intake was expressed per kg0.75 BW (ca. 56 g DM) and tended to be higher (p = .07) in D does when expressed per kg0.67 BW (62 g vs. 55 g DM). Domestic does showed a higher (p < .05) DM, organic matter, crude energy and neutral detergent fibre digestibility (3; 2; 3; 3 percentage points respectively) than W does. The amount of nutrients and energy digested by D does was lower per kg BW (p < .001), similar per kg0.75 BW (p > .05) and tended to be higher per kg0.67 BW (p < .1) than in W does. The diet content of alfalfa did not affect (p > .05) the feed intake nor the diet digestibility. This study suggests that W rabbits exhibit a higher intake per kg BW and a lower digestibility than their D counterparts, which results in similar digestible nutrient and energy intake per kg BW powered to 0.75. The nutritive value of dehydrated alfalfa for rabbits, evaluated through intake and digestibility, seems to be equivalent to their base diets (forage plus concentrate).

Effect of substitution of wheat starch by potato starch on the performance, digestive physiology and health of growing rabbits.

The goal of this research was to study the effect of the substitution of wheat starch by potato starch (PS) on the performance, health and digestion of growing rabbits. Three experimental diets were formulated with 0%, 7% and 14% PS (PS0, PS7 and PS14, respectively) and similar starch contents (22% dry matter basis), proteins and fibre. The three diets were administered to three groups of 48 rabbits from weaning (28 days) to slaughter (70 days), and growth and health measurements were made. Another 10 rabbits per diet (30 rabbits at each age), reared under similar conditions, were slaughtered at 6 to 10 weeks of age, and the digesta were collected to analyse the caecal microbial activity (pH, volatile fatty acids (VFA) levels, fibrolytic activity) and the starch concentration in the ileal digesta. At the same ages, the whole tract digestibility coefficients were measured in 10 other rabbits for each treatment (30 rabbits). The feed intake between 28 and 42 days of age (days) increased by 11% (P < 0.05) in PS0 v. PS14. Over the whole growth period (28 to 70 days), weight gain was similar among diets (40.5 g/day), whereas the feed intake and feed conversion increased (8.5% and 5.2%, respectively; P < 0.05) with the PS14 diet. Mortality and morbidity were not affected by the diets. The starch concentration of the ileal contents increased (P < 0.01) with the addition of PS to the diet (0.39%, 0.77% and 1.08% for diets PS0, PS7 and PS14, respectively). Starch digestibility was 0.8 percentage units higher (99.8% v. 99.0%) with the PS0 diet than the PS14 diet (P = 0.04). The bacterial cellulolytic activity in the caecum tended to be higher with the PS14 diet (P = 0.07). The total VFA caecal concentration increased (P < 0.01) only in 6-week-old rabbits with PS7 compared with PS0 (54.7 v. 74.5 mmol/l). Protein digestibility and ileal starch concentration decreased (P < 0.05) with age (6 v. 10 weeks), and hemicelluloses digestibility increased (P < 0.05). At 10 weeks of age, rabbits showed a higher VFA pool (6.25 mol) and proportion of butyrate (15.9%) and a lower proportion of acetate (79.3%), ammonia level (7.5 mmol/l) and C3/C4 ratio (0.31) than at 6 weeks of age. The intake of potato starch had no effect on the performance, caecal microbial activity or digestive health of growing rabbits.

Age affects the laying performance and egg hatchability of red-legged partridges (Alectoris rufa) in captivity.

Red-legged partridge breeders are frequently reared in captivity with the aim of producing fertile eggs and chicks. However, little is known regarding the role of breeder age on fertility and egg production performance. Therefore, we investigated the effects of breeder age on egg size and shape, flock reproductive performance, fertility, hatchability, and embryonic mortality. In experiment 1, the effects of breeders' age on fertility, hatchability of eggs, and embryo mortality were evaluated. We found that partridge breeder age significantly affected the onset of egg laying, egg production, number and proportion of settable eggs, hatchability, and fertility. Specifically, 1-yr-old females laid their first egg 1 wk later than 2, 3, or 4-yr-old birds. Furthermore, 2-yr-old females produced a significantly higher number of settable and fertile eggs than other females (53.0 vs. 46.4 to 48.5) and had a lower incidence of embryo mortality. In experiment 2, we examined the effects of breeder age, egg size, and egg shape on egg hatchability. We found that small eggs (<17.6 g) had a significantly lower hatchability than medium (17.6 to 18.9 g) or large eggs (>18.9 g). However, we did not observe any significant correlation between egg shape and hatchability. These results suggest that red-legged partridge breeders attain maximum reproductive capacity at 2 yr of age and produce fewer eggs with lower weight and hatchability thereafter.

The value of in vivo real time ultrasonography in assessing loin muscularity and carcass composition of rabbits.

Sixty nine growing rabbits were scanned over the lumbar region using a real time ultrasonography (RTU) machine to estimate loin muscularity and carcass composition. Longissimus thoracis et lumborum muscle (LM) depth, width and area were taken. Animals were weighed (LW), slaughtered and carcass composition was determined. Equivalent measurements to those taken by RTU in vivo were taken on the carcass and muscularity indices were calculated on carcass and in vivo. Simple correlations between the two types of measurements were determined and carcass composition was estimated by simple and multiple regressions. The LW varied from 1200 to 3410g. The simple correlations between carcass and in vivo RTU LM measurements were high (P<0.001) and the LM area was the trait with the highest correlation (r=0.92). Simple correlations between muscularity indices measured by RTU and in carcass were significant (P<0.001). In vivo RTU measurements explained a large amount of the variation of the carcass meat weight (MW) and bone weight (r(2) range from 0.49 to 0.77; P<0.001). Using multiple regression equations to estimate carcass composition, the best fit was obtained with the LW and one or more in vivo RTU measurement. The LW explained 90.6% of the variation of MW in the carcass. In vivo RTU is able to estimate loin muscularity and carcass composition of rabbits with accuracy. The usefulness of in vivo RTU and LW to predict carcass composition of rabbits using multiple regressions was also shown.

Restricting the intake of a cereal-based feed in free-range-pastured poultry: effects on performance and meat quality.

Pastures are assumed to be good sources of alpha-linolenic acid (ALA) and other bioactive compounds. In this study, we evaluated the effects of restricting the intake of a cereal-based feed on the consumption of a legume-based pasture, and consequently on poultry performance and meat quality. Broilers of the RedBro Cou Nu x RedBro M genotype were fed a cereal-based feed at different intake restriction levels (100, 75, or 50% of ad libitum intake) in portable floorless pens located on a subterranean clover (Trifolium subterraneum) pasture. Control birds were maintained at the same site in identical pens but had no access to pasture. The results revealed that, although the growth rate achieved was below the levels expected for the genotype, restriction of cereal-based feed intake had a significant impact on broiler weight gain and feed conversion while leading to an increase in relative leguminous pasture intake (from 1.6 to 4.9% of the total intake, on a DM basis). In addition, bird performance was positively influenced by pasture consumption. The capacity of ingested pasture to modulate carcass characteristics, broiler meat fatty acid profiles, and the meat content of total cholesterol, tocopherols, and to-cotrienols was investigated in broiler chickens slaughtered on d 64. Pasture intake decreased carcass yield (P < 0.05) and meat pH (P < 0.001) and improved breast skin pigmentation (P < 0.001). Consumption of the leguminous pasture had a marginal effect in the vitamin E profiles and cholesterol contents of broiler meat (P < 0.05), although it significantly affected the meat fatty acid profile. Although pasture intake did not influence the linoleic acid content of poultry meat, the levels of n-3 polyunsaturated fatty acids in breast meat [ALA (P < 0.001), eicosapentaenoic acid (P < 0.001), docosapentaenoic acid (P < 0.001), and docosahexaenoic acid (P < 0.001)] were significantly greater in birds consuming the leguminous biomass. Overall, the data suggest an important deposition of ALA and some conversion of ALA to its derivatives in pastured broilers subjected to a restriction of cereal-based feed.

Improving the lipid nutritive value of poultry meat through the incorporation of a dehydrated leguminous-based forage in the diet for broiler chicks.

Dehydrated forages are assumed to be good sources of alpha-linolenic acid (ALA) and lipid-soluble antioxidant compounds (vitamin E homologs and beta-carotene). The effects of including a dehydrated leguminous-based forage in a typical diet for broiler chicken, on performance, meat quality, and fatty acid composition were evaluated. One hundred sixty 1-d-old male commercial broiler chicks (Ross 308) were housed in 20 battery brooders. During the 28-d growth period, the animals were fed ad libitum with a typical maize-soybean high-energy feed having access or not to a dehydrated leguminous-based forage provided in a separate feeder. The results revealed that dehydrated forage intake (which was 11.1% of the total intake) had no impact in broiler performance (P > 0.05). The capacity of ingested forage to modulate broiler meat fatty acid profile and the meat content in total cholesterol, tocopherols, tocotrienols, and beta-carotene was investigated in broiler chicks slaughtered at d 28. Dehydrated forage consumption had no effect on the lipid-soluble antioxidant compounds and cholesterol contents of broiler meat but had a significant effect on meat fatty acid profile. Although forage intake did not affect the linoleic acid and ALA contents in poultry meat, the levels of n-3 long-chain polyunsaturated fatty acids [eicosapentaenoic (P = 0.004), docosapentaenoic (P = 0.010), and docosahexaenoic (P = 0.007)] in breast meat were significantly higher in animals consuming leguminous biomass, which suggest a higher conversion of ALA into its derivatives in these birds. Overall, the data confirms that incorporation of a dehydrated leguminous-based forage in the diet for broiler chicks results in more favorable polyunsaturated fatty acids/saturated fatty acids and n-6/n-3 nutritional ratios for animals slaughtered at earlier stages of grow.

Crop beta-glucanase activity limits the effectiveness of a recombinant cellulase used to supplement a barley-based feed for free-range broilers.

1. The supplementation of diets rich in soluble polysaccharides with microbial cellulases and hemicellulases decreases digesta viscosity and promotes broiler performance. 2. In contrast, recent experiments suggest that polysaccharidases are ineffective for improving the nutritive value of pasture biomass used by free-range broilers. However, the feasibility of using cellulases and hemicellulases to improve the utilisation of cereal-based feeds by pastured poultry remains to be established. 3. A study was undertaken to investigate the capacity of a recombinant cellulase from Clostridium thermocellum to improve the nutritive value of a barley-based feed for free-range pastured broilers of the RedBro Cou Nu x RedBro M genotype. 4. The results show that supplementation of a barley-based diet with a recombinant beta-glucanase had no effect on the performance of free-range broilers, foraging in legume-based diets from d 28 to 56. In addition, the results confirm that the lack of effect of the recombinant enzyme in improving the nutritive value of the barley-based feed does not result from enzyme proteolysis or inhibition in the gastrointestinal tract. 5. Significantly, beta-glucanase activity was identified in the crop of non-supplemented animals. The data suggest that endogenous cellulases originated both from the barley-based feed and from the crop microflora. 6. The results presented here suggest that in older birds of slow-growing genotypes associated with free-range production systems, previously unknown sources of beta-glucanases, such as the feed and microbial symbiotic microflora, can affect the effectiveness of exogenous enzymes added to the feed.

Effect of dietary dehydrated pasture and citrus pulp on the performance and meat quality of broiler chickens.

Some feedstuffs containing significant levels of fiber may be a good source of bioactive compounds that may contribute to improving broiler meat quality. However, high fiber level can have a negative impact on broiler performance. A study was undertaken to investigate the impact of incorporating citrus pulp (5 or 10%) or dehydrated pasture (5 or 10%) on the performance, carcass yield, and characteristics of broiler chickens. A diet containing neither citrus pulp nor dehydrated pasture was used as control. The results on growth performances showed that daily weight gain was reduced by 26% in birds of the 10% citrus pulp treatment (P<0.05). Compared with the control treatment, increases in feed intake occurred in birds consuming diets with 5 or 10% citrus pulp, which resulted in significantly higher feed conversion rates with the 10% level. Under the same incorporation rate, dehydrated pasture had effects less evident on the performances of broiler chicken. In addition, diets containing citrus pulp, displaying higher percentages of soluble nonstarch polysaccharides, increased small intestine relative length, and reduced carcass yield. Inclusion of 10% dehydrated pasture in diets resulted in improved breast skin yellowness (P<0.05). Finally, the results revealed that incorporation of the nonstarch polysaccharide-rich feedstuffs had a major impact on the fatty acid profile (affected 16 of 21 fatty acids) of broiler meat. Polyunsaturated fatty acids content in meat was higher in birds consuming the highest levels of both citrus pulp and dehydrated pasture, leading to increased ratios of polyunsaturated to saturated fatty acids. Together, the results suggest that incorporation of moderate levels of dehydrated pastures in poultry diets has a minor impact on broiler performance and can contribute significantly to improve breast skin yellowness and fatty acid composition of meat.

Pasture intake improves the performance and meat sensory attributes of free-range broilers.

Free-range chickens are assumed to consume low to moderate levels of pasture, although the effects of forage intake in broiler performance and poultry meat quality remain to be established. In addition, despite cellulases and hemicellulases being widely used as feed supplements to improve the nutritive value of cereal-based diets for fast-growing broilers, the potential interest of these biocatalysts in the production of free-range chicken is yet to be established. In this study, broilers of the RedBro Cou Nu x RedBro M genotype were fed a cereal-based diet in portable floorless pens located either on a rainfed subterranean clover (Trifolium subterraneum) pasture or on an irrigated white clover (Trifolium repens) pasture. Control birds were maintained at the same site in identical pens but with no access to pastures. The importance of pasture intake and enzyme supplementation in the performance and meat sensory properties of the free-range chicken from d 28 to 56 was investigated. The results revealed that although cellulase and hemicellulase supplementation had no impact on broiler performance (P > 0.05), birds foraging on legume-based pastures reached significantly greater final BW. The data suggest that the improvement in broiler performance results from increased intake of the cereal-based feed rather than from an improvement in the efficiency of nutrient utilization per se. Interestingly, although the intake of the subterranean clover pasture had no impact on the tenderness, juiciness, and flavor of broiler meat, members of a 30-person consumer panel classified the meat from grazing broilers with greater scores for overall appreciation. Together, the results suggest that pasture intake promotes bird performance while contributing to the production of broiler meat with preferred sensory attributes.

Prediction of carcase and breast weights and yields in broiler chickens using breast volume determined in vivo by real-time ultrasonic measurement.

1. The use of in vivo real-time ultrasonic (RTU) to predict breast and carcase weights and yields in 103 male broiler chickens was evaluated. Breast area (mm(2)), thickness (mm) and volume (cm(3)) were measured by RTU in three identified sites. After RTU measurements, the broiler chickens were weighed (live weight, LW, g) and slaughtered Carcase and breast weights (g) and physical measures of breast area (mm(2)), and thickness (mm) corresponding to the three identified sites, and volume (cm(3)) were recorded. 2. The best simple correlation between RTU and carcase measurements was obtained for breast volume. Breast and carcase weights were well predicted by LW. Furthermore, breast volume measured in carcase or by RTU was better in predicting breast weight and breast and carcase yields. 3. Multiple regression equations were fitted using LW (g) and RTU measurement of breast volume to predict breast and carcase weights and yields. The coefficients of determination were 0.52 and 0.65 for breast and carcase yields, respectively, and 0.92 and 0.99 for breast and carcase weights, respectively.