The objective of this work was to evaluate the effect of protein reduction, with or without the supplementation of limiting amino acids, on the performance and carcass characteristics of meat quails from 22 to 42 days of age in a thermoneutral environment. A total of 324 European quails were randomly allocated into nine diets. The diets were formulated based on the recommended requirement (control) and were differentiated according to crude protein (CP) reduction levels into moderate reduction (10%) and severe reduction (20%). The diets were supplemented or not with limiting amino acids. The diets with severe and moderate protein reduction meeting the methionine + cystine, lysine and threonine requirements led to weight gain equivalent to that of the control quails. The diet with a moderate reduction in CP, with or without meeting the methionine + cystine requirement or meeting the methionine + cystine and lysine requirement, led to the greatest carcass yield and a greater leg weight and were similar to the control treatment. It is observed that supplementation with the crystalline sources of the amino acids is able to improve the performance of the quails, in addition, the attendance of methionine + cystine requirement important factor when the CP levels are reduced. In our studies, diets with 17.5% CP and supplemented with methionine + cystine, lysine and threonine meet the requirements of quails, thus generating a limiting amino acid requirement, so they are recommended for meat quails from 22 to 42 days old housed in thermoneutral environment.

Vitamins play an essential role in broiler nutrition. They are fundamental for normal metabolic and physiological process, and their requirements for poultry are not fixed and can be affected by multiple factors. In contrast, mycotoxins are a challenging issue because they hinder performance and the immune system. Vitamin supplementation above minimum requirements would permit improvement in productive potential, health, bone and meat quality in a situation of mycotoxin challenge. The objective of this study was to determine the influence of optimum vitamin nutrition in diets contaminated with aflatoxin in broilers from 1 to 44 days of age. A total of 1800 Cobb 500 male chicks were randomized to 15 sets of eight treatment groups, each containing 15 birds using a 2 × 2 × 2 factorial design (commercial vitamin levels and high vitamin levels, two levels of aflatoxin – 0 and 0.5 ppm with binder levels of 0 and 10 000 mg/kg). The mash diets were corn and soybean meal based, formulated according to commercial practices. Feed intake, weight gain and feed conversion were analyzed for birds from 1 to 44 days of age. To determine carcass characteristics (carcass yield, breast yield and leg yield) and black bone syndrome, two birds were slaughtered from each group at 45 days. Other analyses included breast tenderness, water loss by dripping and malonaldehyde concentrations. The results demonstrated that broilers that were fed high levels of vitamins showed better weight gain, feed conversion, carcass yield and breast yield than broilers that were fed diets with commercial vitamin levels (P < 0.05); also, broilers that were fed diets containing 0.5 ppm aflatoxin had lower weight gain, carcass yield and breast yield (P < 0.05). The use of 10 000 mg/kg of binder improved (P < 0.05) feed conversion throughout the rearing period. We conclude that aflatoxin negatively affects performance and carcass yield; however, feeding optimum vitamin nutrition improved these performance traits.

Pyrroloquinoline quinone (PQQ), a putative essential nutrient and redox modulator in microorganisms, cell and animal models, has been recognized as a growth promoter in rodents. Growth performance, carcass yield and antioxidant status were evaluated on broiler chickens fed different levels of PQQ disodium (PQQ.Na2). A total of 784 day-old male Arbor Acres (AA) broilers were randomly allotted into seven dietary groups: negative control group (NC) fed a basal diet without virginiamycin (VIR) or PQQ.Na2; a positive control group (PC) fed a diet with 15 mg of VIR/kg diet; and PQQ.Na2 groups fed with 0.05, 0.10, 0.20, 0.40 or 0.80 mg PQQ.Na2/kg diet. Each treatment contained eight replicates with 14 birds each. The feeding trial lasted for 6 weeks. The results showed that chicks fed 0.2 mg PQQ.Na2/kg diet significantly improved growth performance comparable to those in PC group, and the feed efficiency enhancement effects of dietary PQQ.Na2 was more apparent in grower phase. Dietary addition of PQQ.Na2 had the potential to stimulate immune organs development, and low level dietary addition (<0.1 mg/kg) increased plasma lysozyme level. Broilers fed 0.2 mg PQQ.Na2/kg diet gained more carcasses at day 42, and had lower lipid peroxide malondialdehyde content and higher total antioxidant power in plasma. The results indicated that dietary PQQ.Na2 (0.2 mg/kg diet) had the potential to act as a growth promoter comparable to antibiotic in broiler chicks.

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 × 3 factorial arrangement (two genetic groups and three ambient temperatures: 18°C, 25°C and 30°C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.4°C and 63.9%, 24.4°C and 80.2% and 29.6°C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 30°C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group × ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.

A study was conducted on the Teaching and Research Farm of the Rivers State University of Science and Technology, Nigeria to evaluate the nutritional suitability of four treatments, namely a commercial type broiler diet as compared with the commercial diet supplemented with either fresh centrosema (Centrosema molle), pueraria (Pueraria phaseoloides), or waterleaf (Talinium triangulare) leaves. These diets were fed to 120 day-old chicks (Lohmann Brown) over a 62-day period with treatments arranged in a completely randomized design (CRD). Chemical composition of broiler basal diets differed significantly from the three green foliage supplements. Dry matter (DM) of leaf meals ranged from 97.8 to 227.0 g kg−1 which was significantly (P<0.05) lower than that of broiler basal diets which averaged 900 g kg−1. Crude protein (CP) of leaf meals, however, ranged from 182.0 to 244.0 g kg−1 which was generally higher than basal diets (130–153 g kg−1). Similarly, crude fiber (CF) was highest for centrosema and pueraria leaves (330–342 g kg−1) and lowest in basal diets (164–222 g kg−1). However, ether extract (EE) and nitrogen-free extract (NFE) were significantly higher in broiler basal diets. Broiler daily and total feed intake over 62 days were similar between treatments and the control, averaging 112 g d−1, while diets containing waterleaf were slightly (2.5%) lower. Total and daily bodyweight (BW) gains (2110 g and 34 g d−1) were also similar between treatments and the control, except that gains where the broiler diet was supplemented with centrosema foliage were 2.9% higher. A higher feed conversion ratio (FCR) and lower protein efficiency ratio (PER) for the diet supplemented with pueraria indicates a higher feed efficiency and better protein efficiency in the commercial control diet. Carcass characteristics with the commercial control diet included greater (P<0.05) intestinal length and gizzard and spleen weights than with green foliage supplements. However, broiler carcass weight was generally lowest (P<0.05) in the control group (64.3 g/100 g BW) and highest in the waterleaf group (71.3 g/100 g BW). Small differences in carcass weight among the treatments tested reduces the effectiveness of green feeds for practical and economic intensive broiler production. However, increased effectiveness of green feed supplementation for broiler production might likely be observed where broilers are managed on fenced rangelands planted to selected green feeds or in integrated systems where other livestock (rabbits, sheep, goats, etc.) are jointly reared. These results support the recommendation that leaf meals of green feeds should be incorporated into broiler diets in future studies.

A study was conducted to compare the performance of Mukota, Large White (LW) and LW ✕ Mukota F1 pigs given increasing levels of maize cob meal. Sixteen female weaners of each genotype were given, ad libitum, diets containing 0, 100, 200 and 300 g maize cob meal per kg of diet for 14 weeks. The diets were designed to contain similar levels of protein (ca. 160 g crude protein per kg) and energy (ca. 9 MJ metabolizable energy per kg). Average daily food intake per unit metabolic body weight (ADFI per kg M0·75), average daily gain (ADG) and food conversion ratio (FCR) were determined. The pigs were slaughtered and cold dressed mass (CDM) and backfat thickness were determined for each pig. The ADFI per kg M0·75 was similar among the four diets for the three genotypes. The rate of decline in ADG was higher (P < 0·05) in the LW than in the other two genotypes. The FCR in the Mukota was poorer (P < 0·05) than that in the LW and the F1 crosses. The Mukota had the highest (P < 0·05) backfat thickness (K5 and K7·5) values of the three genotypes across the four diets, followed by the F1 crosses. The CDM values for the LW and the F1 crosses were similar and were higher (P < 0·05) than those for the Mukota. The findings indicate that F1 crosses and the Mukota were better able to utilize diets containing high levels of maize cob meal than LW pigs.

The study was conducted to test the hypotheses that sustained restriction of food to maintain constant body weight of market-ready pigs, hereafter terminal maintenance (TM), would (1) decrease the size of gastrointestinal and other visceral organs, (2) increase dressing proportion, and (3) increase lean and decrease fat content and improve the lean: fat ratio of carcass. Forty-eight crossbred castrated male pigs (initial body weight, 23·5 kg) were randomly assigned to eight treatment groups (six pigs per group; one pig per pen). Three comparison groups were included. The ad libitum control group (AL) was slaughtered at the target weight, 105 kg. One group was continuously restricted (CR) to 0·8 of the intake by AL and slaughtered at the target weight. The terminally restricted (TR) group was given food ad libitum to 1·1 times the target weight; then food was restricted to effect weight loss to the target weight before slaughter. Five TM groups were given food ad libitum to the target weight; then TM was administered for various periods (7, 14, 21, 28 and 42 days) before slaughter. CR either had no effect or caused enlargement of visceral organs compared with AL. TR caused reduction of viscera, especially of abdominal-digestive organs. TM caused reduction of most viscera organs (0·001 < P < 0·05). Regression analyses indicated that most abdominal organs were reduced 50 to 70 g/kg per 10 days of terminal maintenance. TM and TR also increased carcass weight (P < 0·05). Catabolism associated with reduction of viscera organs may provide nitrogenous substrates to support the continued lean accretion observed during terminal maintenance. The reduced viscera and increased carcass weight combined resulted in increased dressing proportion (P = 0·06). Regression analyses (weight v. TM-days) showed that lean mass increased (71 g/day; P < 0·05) and fat mass decreased (−52 g/day; P < 0·01). Weight of bone and belly did not change. Differential lean gain, lean gain minus fat gain, during TM occurred at a rate of about 120 g/day.

The effects of pregnancy status (non-pregnant, early to mid (1 to 5 months) and late (> 6 months)) and month of pregnancy on live weight, carcass weight, dressing proportion, bruising and muscle properties were examined in 237 Shorthorn and Brahman crossbred cows (mean live weight 424 kg, 62% pregnant). The cows were transported 1155 km to an abattoir and given access to food and water until slaughter. Mustering to slaughter periods were 5, 6 or 7 days.

The mean gross hot carcass weights for the 89 non-pregnant, 108 early to mid pregnant and 40 late pregnant cows were 207, 199 and 187 kg (P < 0·05). Their respective dressing proportions were 487, 469 and 443 g/kg (P < 0·05). Among the pregnant cows, carcass weight and dressing proportion decreased by 2·95 kg and 6 g/kg, respectively, for each month of pregnancy (P < 0·05).

Cows in late pregnancy had lower mean initial yield (IY) and peak force (PF) shear values for m.longissimus dorsi (LD) than non-pregnant cows. The late-pregnant cows also had the greatest mean pH 24 h post mortem (pH24) and ultimate pH (pHu) values (P < 0·05). They also had a greater proportion of carcasses with high pHu values than the early to mid-pregnant and non-pregnant cows (0·30 v. 0·157 v. 0·079; (P < 005). Among the pregnant cows, mean pH24 increased by proportionately 0·038 and the proportion of high pH24 carcasses by 0·055 for each month of pregnancy (P < 0·05). Pregnancy status had no significant effect on mean fat depth, bruise score, PF-IY value or cooking loss.