Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 51 num. 4 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Carcass characteristics and meat quality of lambs fed high levels of spineless cactus in the diet</b>]]> The objective was to evaluate the effect of increasing the dietary inclusion of spineless cactus (Nopalea cochenillifera Salm Dyck) on the carcass characteristics and meat quality of confined lambs. Thirty-two male Santa Inês lambs with an average age of 140 days and an initial body weight of 20.4 ± 2.60 kg were used in this study. The lambs were housed in individual stalls for 70 days and individually fed a ration with spineless cactus included at 0, 241, 519, or 753 g/kg of dry matter (DM). The lambs were slaughtered, and characteristics of the carcass and meat were recorded and analysed. Inclusion of spineless cactus had a quadratic effect on the bodyweight at slaughter and on the empty bodyweight of the lambs. The inclusion of 500 g/kg of spineless cactus provided the highest predicted cold carcass weight (16.03 kg). There was a quadratic effect of the inclusion of spineless cactus on the weight of meat cuts and leg composition of lambs. The inclusion of spineless cactus did not influence pH, tenderness, and water-retention capacity of the meat. However, the intramuscular fat content increased 1 mg for every 10 g/kg inclusion of spineless cactus in the diet. Quadratic effects were observed of the inclusion of spineless cactus on the weights of the liver, heart, rumen, blood, skin and internal fat of the lambs. Up to 500 g/kg of spineless cactus could be included in the diet of confined lambs. <![CDATA[<b>Role of essential oils in antioxidant capacity and immunity in a rat model of mixed stress</b>]]> Animal wellbeing is a balance between environmental stress and nutrition that regulates homeostasis. Augmentation of animal feed with essential oils can promote homeostasis. The present study was designed to observe the biochemical, immunological, and biological effects of daily administration of a mixture of essential oils (EOM) in a stressed rat model. Forty-eight adult male Sprague Dawley rats were randomly allocated to four groups, namely a control group (C), a stressed group (S), a treated group (Tr), and a stressed group that received the treatment (TrS). The treatment was applied by adding EOM to the water (0.2 ml/l) three days per week for 28 days. Two chronic stressors (isolation and crowding) were applied to animals in groups S and TrS. Total oxidant status (TOS) increased in the S group compared with C, whereas it decreased when fed with EOM. Although TOS was the same in S and C, it increased in Tr compared with C. There was a significant increase in interleukin 4 (IL-4) in S compared with C, and EOM reversed the IL-4 level. Nevertheless, an increase was seen in the weights of the liver, intestine, brain, and testes in TrS compared with S. The increase in water intake was a result of stress, but feeding with EOM decreased water consumption gradually. This study showed that 0.2 ml/l EOM had protective effects on antioxidant status, immunity and liver function, and decreased water consumption under stress conditions. <![CDATA[<b>Nutritional valorisation of cane <i>(Arundo donax) </i>by treatment with sodium hydroxide</b>]]> This study evaluated the effects of sodium hydroxide (NaOH) treatment on the nutritional value of Arundo donax (A. donax). Its ultimate goal was to develop an environmentally friendly animal feed alternative that could be produced sustainably while combatting the spread of A. donax. Plants were collected and dried at 60 °C in an oven with controlled air circulation to determine the dry matter (DM) content. The dry plant material was then sprinkled with an NaOH solution of 2%, 4%, 6%, or 8% and placed in leak-proof containers for four weeks. The chemical and in vitro digestibility properties of treated and untreated A. donax samples were analysed in triplicate. The treatment led to significant decreases in neutral detergent fibre (NDF) from 81.06% DM to 69.39% DM, acid detergent fibre (ADF) from 46.99% DM to 43.19% DM, and ether extract (EE) from 2.06% DM to 1.39% DM, in the untreated samples compared with those treated with 8% NaOH, respectively. In addition, DM digestibility increased from 24.61% to 33.78%, ash content from 11.75% DM to 19.92% DM, and ADL from 7.43% M to 15.38% DM. Thus, treatment of A. donax with an 8% solution of NaOH concentration improved its nutritional value. <![CDATA[<b>Associative effects in diets composed of alfalfa and corn-soybean concentrate fed to growing cashmere goats</b>]]> The associative effects resulting from the proportions of neutral detergent fibre (NDF) and non-fibre carbohydrate (NFC) were explored and assessed by in vitro gas production. Total mixed rations (TMR) composed primarily of alfalfa and corn-soybean concentrate were fed to growing cashmere goats. Treatments were defined by three proportions of NFC and NDF, namely 2.00 (TMR1), 2.35 (TMR2), and 3.00 (TMR3) that were used to grow cashmere goats, and these TRMs were incubated for 48 hours to evaluate their influence on associative effects. The results indicated that the associative influences of these treatments on gas production occurred within the cultures predominantly at 2 - 8 hours, and disappeared gradually as culture time was extended. TMR2 and TMR3 incubation increased gas production compared with that observed in the other groups at all incubation times (P &gt;0.05), and these groups exhibited positive associative effects, particularly during the early hours of incubation (P <0.05). TMR3 displayed the best associative effect. <![CDATA[<b>Effects of thermal stress on physiological state and hormone concentrations in Holstein cows under arid climatic conditions</b>]]> This study was conducted to investigate the effect of heat stress on the physiology of dairy cows and to detect the relationship between rectal temperature (RT) and respiration rate (RR), heart rate (HR), and plasma concentrations of cortisol, thyroxine, and prolactin. During the experiment, 44 Holstein cows were allocated to two groups for each season. The average temperature-humidity index (THI) values were 55 ± 2.31 in winter and 78 ± 1.9 in summer. As the THI values increased from 55 to 78, RR rose by 35 inspirations per minute, HR by 3 beats per minute, and RT by 1.2 °C. In addition, the average concentration of cortisol increased from 19.30 to 21.04 nmol/L, and prolactin from 58.52 to 129.79 ngm/L, whereas free thyroxine decreased from 15.43 to 14.01 pmol/L. Plasma sodium and potassium concentrations were similar in the two seasons. These results confirmed that RT is an indicator of the response in dairy cows to hot environmental temperatures. However, they also showed signs of stress, which were reflected in higher levels of cortisol and in certain physiological responses. <![CDATA[<b>Statistical assessment of feeding corn with higher oil content to piglets in the starter phase</b>]]> The aim of this study was to assess the digestibility coefficients (DC) of corn [maize] with an oil content above 3.46% and its effects on the performance of piglets when fed as dry grain (DG) and as rehydrated corn grain silage (RCGS). In Experiment I, 15 piglets (22.51 + 2.39 kg) were allocated to a reference diet (RD) and to two test diets in which corn in the RD was replaced with DG or RCGS. There were five replications of each treatment. Experiment II involved 36 piglets (14.76 ± 2.72 kg), which were assigned to a control diet with common corn grain and to diets in which DG or RCGS replaced the common corn. There were six replications of each treatment. Data were analysed with four statistical models. Model 1 included only the effect of treatment. Model 2 was similar to Model 1 but included initial bodyweight as a covariate. Model 3 was similar to model 1 but included the interaction of diet and period. Model 4 was similar to Model 3 but included the covariate. The more complicated models were generally preferred to Model 1 as they controlled more of the nuisance variation. Feeding a diet that contained RCGS reduced feed intake and improved feed conversion ratio (FCR). <![CDATA[<b>Effects on egg production and quality of supplementing drinking water with calcium and magnesium</b>]]> This study was conducted to appraise the effects on egg quality and production performance of laying hens when drinking water was supplemented with calcium (Ca) and magnesium (Mg). A total of 384 (64-week-old) Hy-line Brown laying hens were assigned at random to four treatments, which consisted of CON: unsupplemented drinking water; T1: drinking water + 2 mg/L Ca + 250 mg/L Mg; T2: drinking water + 4 mg/L Ca + 510 mg/L Mg /10 L; and T3: drinking water + 5 mg/L Ca and 760 mg/L Mg. The experiment lasted six weeks. Water intake increased linearly in week 1 with the rising levels of Ca and Mg in the drinking water. Increasing the Ca and Mg levels improved eggshell strength (week 2 (P =0.01), week 5 (P =0.01), and week 6 (P = 0.03), and eggshell thickness (week 6) (P =0.02) and reduced the rate at which eggs were broken (week 4) (P =0.01). The supplemental Ca and Mg did not affect egg production, egg weight, Haugh unit, albumen height, eggshell colour, and yolk colour compared with CON. Nor did they influence the Haugh unit and albumen height after storing for 1, 5, 10 and 15 days. In conclusion, adding Ca and Mg to the drinking water increased the thickness and strength of the eggshells. <![CDATA[<b>Dietary <i>Catharanthus roseus </i>modulates intestinal microarchitecture in broilers</b>]]> The study evaluated the efficacy of ethanolic extracts of Catharanthus roseus (C. roseus) in altering growth performance, viscera development and intestinal microarchitecture in broilers. Day-old broiler chicks (n = 175) were randomly divided into seven groups (n = 25/group) with 5 replicates (n = 5). The chicks in the control groups were fed a corn-soya-based basal diet, whereas groups 2 - 4 had the same basal diets supplemented with 0.05%, 0.1%, and 0.2% ethanolic leaf extracts (ELE), respectively. Chicks in groups 5 - 7 were fed the basal diet supplemented with 0.05%, 0.1%, and 0.2% ethanolic root extracts (ERE) of C. roseus, respectively. The growth performance and feed conversion ratio remained unchanged, but feed consumption of birds supplemented with 0.1% ERE increased in weeks 1 and 3. The relative length of the small intestine was lower in the 0.05% ERE group compared with the control. Villus height, width, surface area, and lamina propria thickness were higher in the 0.1% ERE group in all three segments of the small intestine than in the control. Broilers supplemented with 0.1% ERE performed better in terms of feed consumption and improved intestinal microarchitecture of the small intestine.