Effect of dietary supplementation of grape seed extract on the growth performance,lipid profile,antioxidant status and immune response of broiler chickens

Grape seed extracts (GSE) contain several beneficial bioactive constituents; therefore, can be utilized as a potential feed additive in broiler chickens. An experiment was conducted to investigate the effect of supplementation of broiler chicken diets with GSE as a natural antioxidant at levels of 125, 250, 500, 1000 and 2000 ppm on the growth performance, serum lipid profile, liver glutathione-reduced, thigh muscle malondialdehyde and humoral immune response against Newcastle disease virus vaccines. This experiment was performed during the life-span of chickens from 0 to 42 days of age. The results of broilers fed on diet supplemented by GSE were compared with those fed on the basal diet (control) or the basal diet supplemented by butylated hydroxytoluene as a synthetic antioxidant (BHT, 125 ppm). No significant differences were observed in the growth performance, percent livability, total lipid, high and very low-density lipoprotein cholesterols when the use of GSE or BHT were compared with the control. Total cholesterol and low-density lipoprotein cholesterol were significantly decreased after intake of GSE compared with BHT in the feed diet. The glutathione-reduced level in liver tissues was significantly increased by inclusion of GSE, but not by BHT. Inclusion of GSE or BHT decreased significantly the malondialdehyde level found in meat tissue. The antibody titer against Newcastle disease virus vaccines was significantly elevated in 28 and 35-day-old broiler chickens fed with a diet supplemented with GSE or BHT, the former providing a higher response. It can be concluded that GSE can be used as an effective natural antioxidant and immunostimulant agent in broiler chicken diets, and that 125 to 250 ppm can be considered as the optimum dosage.     

Performance,gut morphology and carcass characteristics of fattening rabbits as affected by particle size of pelleted diets

A review of past literature revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Changing diet formulation and subsequent processing conditions may improve pellet texture and potentially affect rabbit performance. In the current study, two isoenergetic and isonitrogenous pelleted diets were formulated, which varied in the particle size of the concentrates (2 and 8 mm, respectively). The objective was to evaluate the effect of different particle sizes of compound diets on performance, nutrient utilisation, gut morphology, and carcass characteristics of fattening Italian White breed rabbits. The finely ground diet led to a significant improvement in feed efficiency and apparent digestibility of crude protein, ether extract, crude fibre and NDF, without any negative effect on gut morphology. Furthermore, a smaller particle size of concentrates in pelleted diets improved carcass traits. Meat colour parameters showed significant differences in longissimus lumborum and biceps femoris due to dietary treatments, but in both muscles pH values 1 h and 24 h after slaughter remained unchanged. It is concluded that a finely ground pelleted diet can be used to improve growth performance of rabbits without affecting carcass parameters.     

Effects of dietary pyrroloquinoline quinone disodium on growth performance,carcass yield and antioxidant status of broiler chicks

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.     

Effects of lycopene supplementation on antioxidant status,oxidative stress,performance and carcass characteristics in heat-stressed Japanese quail

Lycopene, a carotenoid present predominantly in tomatoes, is one of the most efficient antioxidants. This experiment was conducted to evaluate the effects of dietary lycopene supplementation on performance, carcass characteristics, biomarkers of oxidative stress (malondialdehyde (MDA) and homocysteine), and concentrations of vitamins C, E, A, cholesterol, triglyceride, and glucose in Japanese quails (Coturnix coturnix Japonica) exposed to high-ambient temperature of 34 °C. Two hundred and forty Japanese quails (10 day-old) were randomly assigned to eight treatment groups consisting of 10 replicates of three birds. The birds were kept at a temperature-controlled room at 22 °C (Thermoneutral, TN groups) or 34 °C (for 12 h/day; 09.00 am–05.00 pm; Heat stress, HS groups). Birds were fed either a basal (control) diet (TN and HS) or the basal diet supplemented with 50, 100 or 200 mg of lycopene/kg of diet. Lycopene supplementation linearly increased feed intake (P=0.05$P=0.05$), live weight gain (P=0.01$P=0.01$), feed efficiency (P=0.01$P=0.01$) and cold carcass weight (P=0.01$P=0.01$) and yield (P=0.05$P=0.05$) under heat stress conditions but did not show the same effect at thermoneutral conditions (P>0.05$P>0.05$). The interaction Serum vitamin C, E, and A (P=0.01$P=0.01$) concentrations increased linearly in birds reared at high temperature while non-significant changes occurred at TN groups. Homocysteine level in serum and malondialdehyde (MDA) levels in serum, liver, and heart (P=0.001$P=0.001$) linearly decreased in all birds of both TN and HS groups as dietary lycopene supplementation increased. Heat stress-induced increase in serum cholesterol (P=0.01$P=0.01$), triglycerides (P=0.05$P=0.05$) and glucose (P=0.01$P=0.01$) concentrations were linearly reversed by lycopene supplementation. Supplementation of lycopene increased the HDL concentration whereas, the VLDL and LDL concentrations reduced with lycopene supplementation (P=0.01$P=0.01$, linear), particularly at a dietary concentration of 200 mg/kg. Lycopene could not be detected in control birds while a linear increase was observed in the sera of lycopene supplemented birds The results of the study indicate that lycopene supplementation attenuated the increase in oxidative stress and depletion in antioxidants caused by heat stress in Japanese quails.     

Effect of epigallocatechin gallate on growth performance and antioxidant capacity in heat-stressed broilers

This study investigated the effects of epigallocatechin gallate (EGCG) on the growth performance and antioxidant capacity of 35-d-old broilers exposed to heat stress. Broilers, 14 d of age, were divided into four groups with six replicates per group (eight chickens/replicate). Thermoneutral group (Group TN) was fed the basal diet and maintained at 28°C for 24 h/d. The heat-stressed groups were housed at 35°C for 12 h/d and 28°C for 12 h/d and fed the basal diet supplemented with EGCG at 0, 300 and 600 mg/kg diet (Groups HS0, HS 300 and HS600, respectively). Compared with Group TN, heat-stressed groups showed significantly reduced gain, feed intake and serum total protein and glucose levels; inhibited serum alkaline phosphatase activities; and increased serum levels of uric acid, cholesterol and triglycerides and the activity of serum creatine kinase, lactate dehydrogenase and aspartate aminotransferase (p < 0.05). Compared with Group HS0, Group HS600 exhibited an increased gain and feed intake; and normalised blood parameters and enzyme activities. Compared with Group TN, the expression of antioxidant-related liver proteins was decreased in Group HS0 and increased in Groups HS300 and HS600 (p < 0.05). The results suggest that EGCG can improve the growth performance and alleviate the oxidant damage by modulating the antioxidant properties of broilers.     

Effects of dietary combination of chromium and biotin on growth performance, carcass characteristics, and oxidative stress markers in heat-distressed Japanese quail

Environmental stress causes adverse effects in performance and antioxidant status of poultry. Dietary chromium supplementation promotes the growth rate and feed efficiency of growing poultry and these beneficial effects of chromium appear to be greater under stress. Biotin, a member of the vitamin B complex, is involved in the metabolism of carbohydrates, fats, and proteins. In a previous experiment, we examined the effects of chromium picolinate (CrPic) as a chromium source in birds subjected to high environmental temperature and the data showed that supplementation with CrPic ameliorated the deletorious effect of stress. The study was conducted to determine the effects of a supplementation of combination of CrPic and biotin (Diachrome^TM) on performance, carcass characteristics, levels of oxidative stress markers, serum cholesterol, and glucose concentrations in Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature of 34°C. Two hundred forty Japanese quail (10 d old) were randomly assigned to 8 treatment groups consisting of 10 replicates of 3 birds. The birds were kept in a temperature-controlled room at 22°C (thermo-neutral [TN] groups) or 34°C (for 8h/d; 09.00 am to 05.00 pm; heat-stress [HS] groups). Birds were fed either a basal (control) diet (TN and HS) or the basal diet supplemented with either 1, 2 or 4 mg of Diachrome/kg of diet. Heat exposure decreased performance when the basal diet was fed (p=0.001). Diachrome supplementation increased feed intake (p=0.001), body weight (p=0.05), feed efficiency (p=0.01), and carcass traits (p≤0.05) variables linearly in birds reared under HS conditions. Serum vitamin C (p=0.05) and vitamin E (p=0.03) concentrations increased, whereas malondialdehyde (MDA) levels in serum and the liver (p=0.01), thigh muscle (p=0.05), and serum cholesterol and glucose concentrations (p=0.05) decreased in supplemented birds reared at a high temperature. It should be noted that when birds were kept at the thermo-neutral temperature, Diachrome supplementation did not affect (p>0.05) the variables measured, with the exception of a reduction in serum cholesterol and glucose. Results of the present study suggest that Diachrome can be considered a protective dietary supplement by reducing the negative effects of high environment temperature on performance and oxidative stress in quail.     

Effects of temporary intensive feed restriction on performance,nutrient digestibility and carcass criteria of growing male Californian rabbits

The aim of the study was to evaluate the effect of a temporary quantitative feed restriction on growth performance, nutrient digestibility and carcass criteria of rabbits. A total of 80 weaned male Californian rabbits (30 d of age) were randomly assigned to four treatments of 20 rabbits each. The Control group was fed ad libitum during the whole experimental period (days 30–72 of age). For the three restricted fed groups the feed intake was reduced by 15%, 30% and 45% compared to the Control group, respectively. The feed restriction was applied after weaning and lasted for 21 d. Thereafter, at 51 d of age, in all treatments the feed supply returned to ad libitum intake till 72 d of age (AL period). The feed restriction decreased the body weight gain of rabbits (during the restriction period and the whole experimental period, p < 0.001) and improved feed conversion ratio during all tested periods (p < 0.001). In the AL period, the daily body weight gain of all groups was similar. After the AL period, the digestibility of all measured nutrients was significantly higher for animals fed restrictively. Furthermore, feed restrictions significantly decreased the proportion of perirenal and scapular fat and increased relative weight and length of the gastrointestinal tract. Therefore, it can be concluded that the applied feed restriction improved feed conversion, nutrient digestibility and reduced fat at the slaughter age of Californian rabbits, but the reduced body weight gain could not be compensated by a subsequent ad libitum feeding for 3 weeks.     

Housing of growing rabbits in individual,bicellular and collective cages: growth performance,carcass traits and meat quality

During growth (from 27 to 75 days of age), 384 rabbits were kept in different types of wire-net cages: 72 individual cages (72 rabbits; 10 animals/m²), 48 bicellular cages (96 rabbits; 2 rabbits/cage; 18 animals/m²) and 24 collective cages (216 rabbits; 9 rabbits/cage; 18 animals/m²). The rabbits housed in individual cages showed higher daily weight gain both during the fattening period (from 52 to 75 days of age) and during the whole period of growth (43.0 v. 41.8 and 41.5 g/day; P < 0.05), and they had a higher final live weight at 75 days of age (2678 v. 2619 and 2602 g; P < 0.05) compared with the rabbits in the bicellular and collective cages, respectively. Rabbits in individual cages ingested more feed (133 v. 127 and 126 g/day; P < 0.01), but the feed conversion did not differ significantly among rabbits housed in the three types of cages. At slaughter, the carcass traits and meat quality were weakly affected by the housing system. The transport losses were higher in rabbits kept in individual and bicellular cages compared with those reared in collective cages (3.1% and 2.9% v. 2.2%; P < 0.01). In rabbits kept in individual cages, the hind leg muscle to bone ratio was higher (6.35 v. 6.19 and 5.91; P < 0.05) compared with the bicellular and collective cages, respectively. The pH and colour of the longissimus lumborum did not change with the housing system, while the b* index of the biceps femoris was lower (3.04 and 3.32 v. 4.26; P < 0.001) in the rabbits kept in individual and bicellular cages, respectively, than in those kept in collective cages. In conclusion, the rabbits housed in individual cages showed higher daily growth than rabbits kept in bicellular or collective cages, but they had a similar feed conversion and carcass quality. Differently, neither in vivo performance nor slaughter results differed among the rabbits kept in bicellular cages or in collective cages. The meat colour may be affected by the housing system, but to an extent that is hardly perceivable by the final consumer.     

Effects of dietary chromium supplementation on performance, carcass traits, serum metabolites, and tissue chromium levels of Japanese quails

This study was conducted to investigate the effects of various levels of dietary chromium supplementation on performance, carcass traits, blood chemistry, and tissue distribution of chromium (Cr³⁺) in quails. Two hundred forty 1-d-old Japanese quails were divided into five groups with four replicates and were fed a basal diet or the basal diet supplemented with 20, 40, 80, or 100 mg/kg Cr (CrCl₃·6H₂O) until 38 d of age. Chromium supplementation decreased carcass fat percentage, serum low-density lipoprotein (LDL), and glucose and increased serum magnesium (Mg) and Cr content of kidney, liver, and muscle. In conclusion, 20, 40, 80, or 100 mg/kg Cr supplementation to quail diet had no effect on performance, chemical composition of carcass except fat percentage, serum protein, calcium (Ca), and inorganic phosphorus (Pi) levels, but reduced serum glucose, LDL and fat percentage of carcass. Chromium is accumulated mainly in the kidneys and liver.     

Effects of different levels of selenium on growth performance and immunocompetence of broilers under heat stress

An experiment was undertaken to evaluate the effect of dietary selenium (Se) levels on growth performance and immune competence of broilers under heat stress. Birds were raised in either a thermoneutral (TN, 23.9°C constant) or heat stress conditions (HS, 23.9°C to 38°C cycling) and were fed a corn-soybean meal basal diet supplemented with Se at 0, 0.2 and 0.4 mg/kg. A total of 240 one-day-old male broiler chicks were randomly assigned to six groups; each group had four replicates of 10 birds. Body weight and feed intake were not influenced by dietary Se, while feed conversion was significantly improved by a Se-supplementation of 0.2 mg/kg. HS significantly reduced body weight, feed intake and feed conversion. Numbers of abdominal exudate cells (AEC), percentage of macrophages in AEC, phagocytic macrophages, internalized opsonised and unopsonised sheep red blood cells (SRBC) were significantly increased by dietary Se. Both primary and secondary antibody responses were characterised by increasing titres of antibody to SRBC by dietary Se when birds were exposed to HS (p < 0.05). Lymphoid organ weights, antibody responses, incidence of macrophages in AEC, and phagocytic ability of macrophages were also significantly reduced under HS. These results indicated that HS severely reduced growth performance and immunocompetence of broilers, whereas the immune response of broilers improved by dietary Se supplementation under HS.     

Effects of dietary grape seed extract on growth performance,amino acid digestibility and plasma lipids and mineral content in broiler chicks

Polyphenols are chemically and biologically active compounds. Grape seed extracts (GSEs) have been widely used as a human food supplement for health promotion and disease prevention. However, there is little information regarding its application in animal feeds. An experiment was conducted to investigate the effect of inclusion of GSE at 0.025, 0.25, 2.5 and 5.0 g/kg in a wheat soya bean control diet on growth performance, protein and amino acid (AA) digestibility and plasma lipid and mineral concentrations in broiler chickens at 21 days of age. Performance was not affected by dietary treatment except in the case of birds fed the diet with the highest GSE concentration, which showed a worsening of weight gain and feed conversion. Apparent ileal digestibility (AID) of protein was significantly reduced in the birds fed the highest concentration of GSE, which also had a reduction on the AID of arginine, histidine, phenylalanine, cystine, glutamic acid and proline compared with those fed control diet. The inclusion of graded concentration of GSE in the chicken diets caused a significant linear decrease in the concentrations of plasma copper, iron and zinc. Plasma cholesterol, triglycerides and lipoproteins (high-density lipoprotein, low-density lipoprotein and very-low-density lipoprotein) concentrations were not affected by dietary GSE. In conclusion, this study demonstrated that incorporation of GSE in chicken diets up to 2.5 g/kg had no adverse effect on growth performance or protein and AA digestibility. Feed conversion was reduced and growth rate was retarded, when chickens were fed 5 g/kg of GSE. This study also indicated that grape polyphenols reduce the free plasma minerals.     

The effect of immunocastration and a diet based on granulated barley on growth performance and carcass,meat and fat quality in heavy gilts

A total of 48 Duroc×(Landrace×Large White) gilts of 33.2 kg BW were used to investigate the influence of immunocastration and diet on growth performance and carcass, meat and fat quality. Four treatments were arranged factorially (2×2) with two sexes (immunocastrated gilts: IG v. entire gilts: EG) and two dietary treatments (a commercial feedstuff as control v. granulated barley as a single major ingredient) provided during the finishing period (from 103 to 126 kg BW). There were four replicates of three pigs per treatment. At the end of the trial, the IGs grew faster (P<0.05) and ate more feed (P<0.05) than the EGs. Carcasses from the IGs had thicker backfat depth than those from the EGs (P<0.01) and carried out a lower percentage of rejected carcasses (P<0.05) at slaughterhouse owing to lack of fat. Meat from the IGs tended to have higher intramuscular fat (IMF) content in the Longissimus thoracis (LT) muscle than that from the EGs (P=0.09). In addition, immunocastration increased the total saturated fatty-acid proportion in subcutaneous fat and IMF (P<0.001) and decreased the total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) percentages in subcutaneous backfat (P<0.05 and P<0.001, respectively) and in IMF (P<0.01 and P=0.06, respectively). The use of a diet based on granulated barley during the finishing period had no effect on growth performance but tended to increase IMF content in the LT muscle (P<0.06), and increased MUFA (P<0.05) and decreased PUFA (P<0.01) proportions in omental fat. It is concluded that immunocastration of gilts intended for dry-cured ham industry improved some aspects of growth performance and carcass and meat quality, whereas granulated barley had scarce effect on productive traits and fatty-acid profile but tended to improve IMF content.     

Effects of water restriction on growth performance,feed nutrient digestibility,carcass and meat traits of rabbits

The study investigates the effects of a post-weaning water restriction on performance, nutrient digestibility, carcass traits and meat quality of 84-day-old rabbits. A total of 1388 weaned rabbits (35 days) were randomly divided into two groups on the basis of BW and sex. The two groups were fed the same diets ad libitum both in the post-weaning (35 to 60 days) and fattening (61 to 84 days) periods. In the post-weaning period, one group (AL) also received drinking water ad libitum, whereas the other (WR) had a water restriction from 35 to 41 days 2 h/day; from 42 to 48 days 2.5 h/day; from 49 to 55 days 3 h/day; and from 56 to 60 days 4 h/day. During the fattening period, both groups had water-free access. Individual live weights and feed intake per cage were recorded weekly for 32 cages randomly chosen per group (64 rabbits) to calculate the BW gain, feed intake and feed conversion ratio (FCR). The apparent digestibility values of nutrients were measured using acid-insoluble ash. Carcass data were collected from 16 rabbits (8 males and 8 females) per group selected for similar final BW in both groups. Mortality from 35 to 60 days was higher in the AL group (10.1% v. 5.2%, for AL and WR, respectively, P < 0.0001). BW gain was higher for the AL group during both the post-weaning (+22.4%, P < 0.01) and the entire period (+7.5%, P < 0.05). Water restriction reduced feed intake both in the post-weaning (−17.4%, P < 0.0001) and in the entire period (−9.9%, P < 0.05). During the fattening period, FCR was lower for the WR group (5.15 v. 5.75 g/g, for WR and AL, respectively, P < 0.05). The apparent digestibilities of dry matter, organic matter, NDF, ADF and cellulose were greater in the restricted rabbits (+4.7%, +4.5%, +10.2%, +18.8% and +12.8%, P < 0.01, P < 0.01, P < 0.05, P < 0.01, P < 0.05, respectively). Perirenal and scapular fat percentages were higher in the AL rabbits (+30.7% and +116.6%, P < 0.01 and P < 0.001, respectively). Water restriction increased saturated fatty acids (C16:0, +12.9%, P < 0.05), lauroleic acid (C12:1, +75.0%, P < 0.01), n-3 polyunsaturated fatty acids (C20:5, +50.0%, P < 0.01 and C22:5, +16.6%, P < 0.05) and the n-3/n-6 ratio (+28.6%, P < 0.05). The applied water restriction between 35 and 60 days executed during the winter months improved the digestive health of rabbits, with no negative effects on carcass traits, or physical and chemical meat characteristics. However, from the animal welfare point of view, a water restriction can be criticized as a method to restrict feed intake.     

A comparative study among dietary supplementations of antibiotic,grape seed and chamomile oils on growth performance and carcass properties of growing rabbits

The main objective of this study was to evaluate the effect of chamomile oil (Ch), grape seed oil (GS), their mixture and antibiotic (colistin) (AN) as feed addetives on the productivity of growing rabbits as well as in vitro study to evaluate the antimicrobial activity of both Ch and GS oils. To achive this objective, a total of 96 New Zealand (NZW) weaned rabbits, 5 weeks-old were randomly allotted into eight groups. Rabbits were kept under observation for eight weeks and the trial ended at thirteen weeks-old. The experimental treatments were: 1) Basal diet (BD); 2) BD + antibiotic; 3) BD + 0.5 ml GS/ kg diet; 4) BD + 1.0 ml GS/ kg diet; 5) BD + 1.5 ml GS/ kg diet; 6) BD + 0.5 ml Ch/ kg diet; 7) BD + 1.0 ml Ch/ kg diet and 8) BD + 1.5 Ch/ kg diet. Live body weight (LBW) was markedly elevated (p < 0.05) in groups fed on ration included feed additives compared with the control at weeks 9 and 13 of age. Cumulative body weight gain (BWG) and feed intake (FI) increased (p < 0.05) throughout 5–9 and 5–13 weeks of age in rabbits fed rations plus the studied additives. Feed conversion ratio (FCR) was insignificantly altered by dietary feed additives. Spleen and intestine relative weights reduced (p < 0.05) in groups treated with different studied additives. In view of the experiment finings, it could be concluded that dietary supplementation of GS and Ch have a positive impact on the productivity of growing rabbits than that of the control and antibiotic-treated groups.     

A comparative study among dietary supplementations of antibiotic,grape seed and chamomile oils on growth performance and carcass properties of growing rabbits

The main objective of this study was to evaluate the effect of chamomile oil (Ch), grape seed oil (GS), their mixture and antibiotic (colistin) (AN) as feed addetives on the productivity of growing rabbits as well as in vitro study to evaluate the antimicrobial activity of both Ch and GS oils. To achive this objective, a total of 96 New Zealand (NZW) weaned rabbits, 5 weeks-old were randomly allotted into eight groups. Rabbits were kept under observation for eight weeks and the trial ended at thirteen weeks-old. The experimental treatments were: 1) Basal diet (BD); 2) BD + antibiotic; 3) BD + 0.5 ml GS/ kg diet; 4) BD + 1.0 ml GS/ kg diet; 5) BD + 1.5 ml GS/ kg diet; 6) BD + 0.5 ml Ch/ kg diet; 7) BD + 1.0 ml Ch/ kg diet and 8) BD + 1.5 Ch/ kg diet. Live body weight (LBW) was markedly elevated (p < 0.05) in groups fed on ration included feed additives compared with the control at weeks 9 and 13 of age. Cumulative body weight gain (BWG) and feed intake (FI) increased (p < 0.05) throughout 5–9 and 5–13 weeks of age in rabbits fed rations plus the studied additives. Feed conversion ratio (FCR) was insignificantly altered by dietary feed additives. Spleen and intestine relative weights reduced (p < 0.05) in groups treated with different studied additives. In view of the experiment finings, it could be concluded that dietary supplementation of GS and Ch have a positive impact on the productivity of growing rabbits than that of the control and antibiotic-treated groups.     

Tick susceptibility and its effects on growth performance and carcass characteristics of Nguni, Bonsmara and Angus steers raised on natural pasture

The objective of the current study was to compare tick loads, growth and carcass characteristics of dipped and non-dipped Nguni, Bonsmara and Angus steers raised on natural pasture. One hundred 7-month-old castrated weaners were kept at the University of Fort Hare Farm for 12 months. There were 30 weaners each of Angus and Bonsmara, and 40 weaners of the Nguni breed. Half the Bonsmara, Angus and 14 Nguni weaners were dipped every fortnight. The rest were not dipped. Monthly weights and tick counts under the tail, on scrotum, belly, sternum and ears of the steers were recorded. The dipped Nguni steers had lowest (P < 0.05) tick counts, and the non-dipped Angus steers had the highest (P < 0.05) tick counts. There were more ticks (P < 0.05) during the warm wet season than during the cool dry season. Ears had the highest (P < 0.05) tick infestation. Average daily gain (ADG) was similar (P > 0.05) among the three breeds. The non-dipped Bonsmara steers had the heaviest (P < 0.05) carcasses (142 ± 5.4) while the non-dipped Nguni steers had the lightest (P < 0.05) carcasses (111 ± 4.5 kg). The non-dipped Bonsmara had the highest (P < 0.05) eye muscle area (3996 ± 120.8 mm2) while the non-dipped Angus had the smallest (P < 0.05) eye muscle area (3291 ± 210.6 mm2). The non-dipped Bonsmara also had the highest (P < 0.05) dressing percentage (53.8 ± 1.01) while the non-dipped Nguni had the lowest (P < 0.05) dressing percentage (50.3 ± 0.84). The current study has shown that while the non-dipped steers had higher (P < 0.05) tick loads than the dipped steers, their growth and carcass characteristics were similar (P > 0.05). The study has also shown that, despite being a small-framed breed, the Nguni steers had similar (P > 0.05) ADG to the large-framed Bonsmara and Angus steers. Therefore, the Nguni cattle have the potential to produce organic beef. However, a reasonable assessment of organic beef production potential of the Nguni requires an evaluation of its meat quality traits under natural pasture.     

The effect of dietary methionine levels on fattening performance and selected blood and tissue parameters of turkeys

A total of 490 eight-week-old female Hybrid Converter turkeys (body weight 4.11 ± 0.03 kg) were divided into 5 groups with 7 replicates of 14 birds each. For 8 weeks, basal diets were supplemented with methionine (Met) at following levels (weeks 9–12/weeks 13–16 of age): Group 1 – 0.34/0.29%, Group 2 – 0.39/0.34%, Groups 3 and 4 – 0.45/0.38% and 0.51/0.41%, respectively, Group 5 – 0.58/0.47%. Only in the first feeding phase the body weight gain (BWG) was affected by Met levels with the significantly highest BWG in Group 3. No treatment effects were found for feed conversion ratio, carcass yield, carcass composition and meat colour. The blood superoxide dismutase activity was significantly highest in Groups 2 and 3. The concentrations of reduced glutathione in the liver were linearly increased (p = 0.018), whereas the ratio of reduced glutathione to oxidised glutathione was highest in Group 3 (quadratic contrast, p = 0.004). It can be concluded that turkeys from Group 3 (Met levels age depending 15% and 10% above recommendations by NRC) were characterised by a well-balanced physiological response. Attention should be paid to the immune response of birds to higher dietary Met levels: plasma IgA concentrations decreased, whereas IL-6 and TNF-α levels increased in turkeys fed diets with the highest Met content.     

Effect of breeding system, cycle and cage size during fattening on rabbit doe and growing rabbit performance under heat stress

In order to evaluate heat stress and circadian rhythm 46 nulliparous rabbit does with a BW of 3.67 ± 0.05 kg (s.e.) were used. They were clipped once or not and rectal temperature, feed and water intake were recorded for 24 h. From this group, 43 rabbit does were mated 7 days after rectal measurements, and randomly assigned to one out of two breeding systems (including in both systems rabbit does that had been clipped or not). In the control one (C) rabbit does were mated 14 days after parturition and litter weaned at 35 days of age, and in the extensive one (E) they were mated 21 after parturition and weaned at 42 days of age. Rabbit doe and litter performance were recorded for 6 months (first three cycles). Two hundred twenty-eight weaned rabbits were divided into two cage sizes: 0.5 and 0.25 m² with eight and four rabbits per cage, respectively, to study growing performance. Farm and rectal temperatures were minimal and feed and water intake maximal during the night (P < 0.001). Unclipped rabbit does showed higher rectal temperature (P = 0.045) and lower feed intake (P = 0.019) respect to clipped does, which are symptoms of heat stress. Neither breeding system nor cycle number influenced fertility, total number of kits born, born alive or dead per litter (91.6%, 6.98, 5.80 and 1.19 on average, respectively). Kit mortality during lactation tended to increase in E compared with C group (48.5% v. 63.4%; P = 0.070), reducing the number of kits at weaning per litter by 33% (P = 0.038). It also increased in the second and third cycles compared with the first (P ⩽ 0.054). It resulted that feed efficiency (g weaned kits/g feed intake does + litter) tended to decrease in E respect C group (P = 0.093), whereas it was impaired successively from the first to the third cycle by 48% (P = 0.014). Growing rabbits from the E group were heavier at weaning (by 38%; P < 0.001), showed a higher feed intake (+7.4%) and lower feed efficiency (−8.4%) throughout the fattening period (P ⩽ 0.056) respect to C group. However, age at slaughter was not different respect to C group (77.3 days on average). Cage size had minor influence in growing performance. In conclusion, rabbit doe and litter productivity impaired when lactation is extended from 35 to 42 days and along successive reproductive cycles.     

Dog food production using curcumin as antioxidant: effects of intake on animal growth,health and feed conservation

ABSTRACT

The objectives of this study were to produce dog food containing curcumin replacing synthetic antioxidants, to evaluate its beneficial effects on animal growth and health. Curcumin (100 mg/kg) was added after the extrusion process along with the other micronutrients. The final concentration of curcumin was 32.9 mg/kg. The control feed was composed of the same ingredients without curcumin. After a storage of 6 months, feed composition and pH did not differ; however, the feed with curcumin showed lower protein oxidation, lipid peroxidation and higher total antioxidant capacity. After 2 months of feed production, 12 young Beagle dogs received either curcumin-containing food (n = 6) or the control diet (n = 6). The animals were fed twice a day using individual kennels. Blood samples were taken on d 1, 35 and 42. During the first 30 d of the study, the animals had natural infectious diseases that were controlled with anti-protozoals and antibiotics. Greater numbers of red blood cells were observed in dogs fed with curcumin (d 35 and 45), and there were greater numbers of white blood cells as a consequence of increased neutrophils on d 42. At the end of the experiment, a significant reduction in the number of lymphocytes was observed in dogs that ingested curcumin (d 42), suggesting an anti-inflammatory effect, manifested as a decrease in globulin levels. In the final 15 d of the experiment, the animals were clinical healthy. Higher serum levels of glucose, urea, triglycerides and cholesterol were observed in dogs fed with curcumin. Curcumin increased the activity of several antioxidant enzymes in addition to non-protein thiols and the total antioxidant capacity in the serum, consequently reducing levels of oxygen reactive species. Curcumin supplementation of dogs did not favour growth or weight gain. Neverthless, it was concluded that curcumin improved animal health, with emphasis on the stimulation of the antioxidant system and evidence of an anti-inflammatory effect.     

Effects of dietary grape proanthocyanidins on the growth performance,jejunum morphology and plasma biochemical indices of broiler chicks

Grape proanthocyanidins (GPCs) are a family of naturally derived polyphenols that have aroused interest in the poultry industry due to their versatile role in animal health. This study was conducted to investigate the potential benefits and appropriate dosages of GPCs on growth performance, jejunum morphology, plasma antioxidant capacity and the biochemical indices of broiler chicks. A total of 280 newly hatched male Cobb 500 broiler chicks were randomly allocated into four treatments of seven replicates each, and were fed a wheat–soybean meal-type diet with or without (control group), 7.5, 15 or 30 mg/kg of GPCs. Results show that dietary GPCs decrease the feed conversion ratio and average daily gain from day 21 to day 42, increase breast muscle yield by day 42 and improve jejunum morphology between day 21 and day 42. Chicks fed 7.5 and 15 mg/kg of GPCs show increased breast muscle yield and exhibit improved jejunum morphologies than birds in the control group. Dietary GPCs fed at a level of 15 mg/kg markedly increased total superoxide dismutase (T-SOD) activity between day 21 and day 42, whereas a supplement of GPCs at 7.5 mg/kg significantly increased T-SOD activity and decreased lipid peroxidation malondialdehyde content by day 42. A supplement of 30 mg/kg of GPCs has no effect on antioxidant status but adversely affects the blood biochemical indices, as evidenced by increased creatinine content, increased alkaline phosphatase by day 21 and increased alanine aminotransferase by day 42 in plasma. GPC levels caused quadratic effect on growth, jejunum morphology and plasma antioxidant capacity. The predicted optimal GPC levels for best plasma antioxidant capacity at 42 days was 13 to 15 mg/kg, for best feed efficiency during grower phase was 16 mg/kg, for best jejunum morphology at 42 days was 17 mg/kg. In conclusion, GPCs (fed at a level of 13 to 17 mg/kg) have the potential to be a promising feed additive for broiler chicks.