Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 41 num. 4 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Dietary effects of Ca-zeolite supplementation on some blood and tibial bone characteristics of broilers</b>]]> This study was conducted to investigate the effects of differing amounts of natural Ca-zeolite on bone and some blood parameters. A total of 240 day-old Ross 308 broiler chicks were assigned to four treatments with three replicates, each containing 20 day-old chicks of mixed sex. A clinoptilolite+mordenite type of zeolite was added in the broiler diets at levels of 0 g/kg, 10 g/kg, 30 g/kg, and 50 g/kg. Stocking density was 14 broilers/m². During the six-week trial, blood parameters and bone characteristics were monitored. The inclusion of Ca-zeolite, at various levels, did not have any significant effect on the concentration of blood serum biochemical parameters; serum glucose, cholesterol, total protein, uric acid; concentrations of Ca, P, Na, K, Cl, and on tibial bone characteristics (tibia weight, ash, volume, specific gravity, and Ca and P contents) in the two sexes and mixed-sex between the groups at 21 and 42 days of age. <![CDATA[<b>Effects of dietary dihydropyridine on laying performance and lipid metabolism of broiler breeder hens</b>]]> The experiment was conducted to investigate the effects of dihydropyridine supplementation on the laying performance and lipid metabolism of broiler breeder hens. A total of 720 forty-five week old broiler breeder hens were randomly divided into four experimental groups, each group consisting of six replicates of 30 birds. For 10 weeks the birds were fed a maize-soybean meal diet containing 0, 100, 200, 300 mg dihydropyridine/kg, in the respective treatment groups. The daily egg weight and daily feed intake were not affected by dihydropyridine supplementation, but the laying rate and feed efficiency were significantly increased. The percentage of abdominal fat and percentage of liver fat were significantly decreased by dietary dihydropyridine. A level of 100 mg dihydropyridine/kg had no effect on the hormone-sensitive triglyceride lipase (HSL) activity in the liver or abdominal fat, though higher levels of dietary dihydropyridine (200 mg/kg or 300 mg/kg) increased HSL activity in the liver and abdominal fat. The concentration of cyclic adenosine monophosphate (cAMP) and superoxide dismutase activity were significantly increased by dihydropyridine, but the malondialdehyde content decreased. The apolipoprotein B concentration was increased at levels of 100 and 200 mg dihydropyridine/kg, but the 300 mg level had no effect on apolipoprotein B, compared with the control group. The triiodothyronine concentration was significantly increased by dietary dihydropyridine. It is concluded that supplementing dihydropyridine in the diet has a beneficial effect on the laying performance and regulates the fat metabolism of broiler breeder hens. The results suggest that the supplementation of 200 mg dihydropyridine/kg diet is the optimal dose for broiler breeder hens. <![CDATA[<b>The effect of tannin with and without polyethylene glycol on <i>in vitro</i> gas production and microbial enzyme activity</b>]]> The aim was to determine the effect of tannin on the nutritive value and microbial enzyme activity in vitro. The leaves and pods of the Acacia sieberiana and Acacia nilotica trees were subjected to chemical analysis and in vitro fermentation with and without polyethylene glycol (PEG; 35 mg/g). Gas production (GP), true degradability (TD) and the proteolytic and fibrolytic enzyme activities in digesta were determined. Data analyses accounted for the effects of feed type, feed fraction, PEG and their interactions. Leaves and pods had similar NDF and ADF contents in A. sieberiana but differed in both attributes in A. nilotica. The leaves had a higher protein, but lower condensed tannin (CT) contents than the pods. A. sieberiana had more CT than A. nilotica, but both had a similar maximum GP. PEG increased the maximum GP, stimulated GP from the soluble fraction and shortened the lag phase. PEG increased the TD for leaves and pods of A. sieberiana, but suppressed TD in fractions of A. nilotica. PEG also increased the activity of protease enzymes, xylanase, endo- and exocellulases, indicating that tannins depress the digestibility of feeds partly by suppressing the activity of these enzymes. Consequently, condensed tannin depressed the digestibility of feed in the rumen by affecting the activity of enzymes involved in carbohydrate and protein breakdown, the effects of which could be reduced with the use of PEG. <![CDATA[<b>Prediction of energy requirements of Murciano-Granadina preruminant female kids using the National Research Council</b>]]> Data collected on metabolizable energy (ME) intake and growth performance of preruminant female kids of the Murciano-Granadina breed was used to assess the accuracy of the latest U. S. National Research Council (NRC) recommendations to predict their energy requirements. Female kids were fed a milk replacer individually, according to appetite three times a day from two to five weeks of age. The mean initial body weight and average daily weight gain (± SE) were 3.31 ± 0.08 kg/d and 120 ± 3 g/d. Daily ME intake, expressed relative to metabolic body weight (BW0.75), decreased linearly with age from 1085 to 970 kJ/kg BW0.75/d, and there was nearly a constant ratio of ME requirements for maintenance. The observed ME intake was 5.4% higher than the ME requirements, calculated according to NRC, probably due to the energy content of the weight gain. It was concluded that the energy system model of the NRC is accurate enough to calculate the ME requirements of preruminant female kids of the Murciano-Granadina breed. <![CDATA[<b>Effects of bacterial silage inoculants on whole-crop maize silage fermentation and silage digestibility in rams</b>]]> This study evaluated the effects of ensiling whole-crop maize with bacterial inoculants, Lactococcus lactis (LL) and Lactobacillus buchneri (LB), on the fermentation and nutrient digestibility in rams. Whole-crop maize (265 DM g/kg) was ensiled for 90 days in 210 L drums with no additive, or with LL or LB. After three months, the drums were opened and the silage was sampled for fermentation characteristics. Diets were produced by mixing the whole-crop maize silage with lucerne hay (90 : 10) on an "as fed" basis, and a digestibility study was conducted using five South African Mutton Merino rams (37.2 ± 2.2 kg live weight) per treatment. Inoculating maize silage with LL and LB reduced ammonia nitrogen concentration, but did not affect silage pH. The concentration of lactic acid was increased with LL compared to the other treatments. A higher concentration of acetic acid was obtained with LB inoculation compared to the other treatments. The aerobic stability of the silage was improved with LB while it was reduced with LL inoculation, as indicated by a higher CO2 production than the latter. The intake and digestibility of dry matter, organic matter, crude protein and fibre were improved by inoculation. Furthermore, inoculations resulted in improved nitrogen retention. It was concluded that the inoculants improved silage fermentation and diet digestibility. Inoculation with LB improved aerobic stability and LL inoculation reduced it. <![CDATA[<b>Effect of concentrate supplementation during early lactation on plasma IGF-I concentrations and reproductive performance of dairy cows</b>]]> An experiment was conducted to assess the effects of body condition score (BCS) at calving and level of feed supplementation during early lactation on the Insulin-like growth Factor-I (IGF-I) and reproductive performance in 72 Holstein cows in a pasture-based system following seasonally-synchronized calving. At the start of the seasonal breeding, plasma IGF-I concentrations in cows that had recommenced ovarian activity with detected oestrus were compared with those in anoestrus. The cows (n = 72) were managed over a period of five months to calve in a BCS of 4, 5 or 6 - using a scale from 1 (thin) to 8 (obese). The cows were maintained on pastures and supplemented during early lactation with either 1 or 6 kg grain per day. The BCS at calving did not affect plasma IGF-I concentrations. The plasma IGF-I concentration at week 10 was elevated at the higher level of grain supplementation (87.8 vs. 72.1 ng/mL). Higher conception rate following the first insemination of cows calving with a BCS of 6 (71% vs. 46% and 37% for a BCS of 4 and 5, respectively) was associated with more cows in that group conceiving during the first three weeks of the artificial insemination (AI) programme (75% vs. 46% and 46% for a BCS of 4 and 5, respectively). At weeks 0 and 10, cows that commenced ovarian activity by the start of the intensive AI programme, recorded higher plasma IGF-I concentrations than anoestrous cows. These findings indicate that diet can affect the plasma IGF-I levels, which in turn may be involved in affecting the resumption of cyclic ovarian activity and conception in dairy cows. <![CDATA[<b>Effects of a dual-purpose bacterial inoculant on the fermentation characteristics of high-moisture maize silage and dairy cattle performance</b>]]> The objective of this study was to investigate the effects of inoculating Lactisil Maize, a dual-purpose inoculant, on the fermentation characteristics and nutritive value of high-moisture maize silage and the performance of lactating cows receiving the silage in their diets. Whole-crop maize was harvested at 253 g dry matter (DM)/kg fresh crop. Maize silage was produced with or without Lactisil Maize and ensiled in two different bunkers. Eight multiparous lactating Holstein dairy cows were used in a replicated 2 × 2 Latin square experimental design and were fed total mixed rations that contained 230 g/kg of either inoculated or control maize silage. Inoculation did not affect the nutritive value or the aerobic stability of the maize silage, but increased the neutral detergent and acid detergent fibre fractions of the silage. However, inoculation increased the concentrations of acetic acid and lactic acid, but reduced ammonia N concentration compared to the control. Cows fed the Lactisil Maize-inoculated silage had a lower DM intake, milk yield, and yields of milk fat and milk protein were lower, compared to control. The digestibility of nutrients was not affected by inoculation. It was concluded that although Lactisil Maize inoculation improved the fermentation quality of high-moisture maize silage, it did not improve aerobic stability of the silage or the production performance of dairy cows compared to the control. <![CDATA[<b>The effects of wilting, molasses and inoculants on the fermentation quality and nutritive value of lucerne silage</b>]]> The objective was to determine the effects of wilting, molasses and inoculants on the biochemistry and in vitro and in situ digestion of lucerne silage. Lucerne containing 200 g/kg of dry matter (DM) was ensiled as fresh or wilted (370 g/kg DM). Molasses, at application rates of 0, 50 and 100 g molasses/kg DM, was added to the chopped lucerne. Within each molasses treatment, the lucerne was applied with distilled water or with the inoculants, Ecosyl or Lalsil. Wilting lucerne increased the silage DM and water soluble carbohydrates and decreased neutral detergent fibre, acid detergent fibre, ammonia and the acetate content of the silage. Adding 50 and 100 g molasses/kg to wilted lucerne and 100 g molasses/kg to fresh lucerne lowered the silage pH. Adding molasses to wilted lucerne increased the acetate content of the silage. In wilted but not in fresh lucerne both inoculants decreased the concentration of unavailable N in the silage. In wilted lucerne, Lalsil, but not Ecosyl, reduced the silage acetate level and in fresh lucerne both inoculants reduced the acetate level. Lalsil was more effective in wilted silages in improving the fermentation quality than Ecosyl. Both inoculants enhanced the 24-h rumen degradation of silage DM, with Lalsil being effective in wilted lucerne and Ecosyl in fresh lucerne. Molasses, at 100 g/kg, improved the in vitro silage organic matter digestion at 6, 8, 36 and 48 h post-incubation. It was concluded that inoculating lucerne crops with Lalsil improved the fermentation quality as well as nutritive value and lowered proteolysis. These effects were more pronounced in silage with a high DM content. <![CDATA[<b>Ruminal protein and fibre degradability of lucerne hay as affected by regrowth period and dairy breed</b>]]> The chemical composition of roughages constantly changes while it grows towards maturity. The effective dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) degradabilities of lucerne hay (LH), harvested after regrowth periods of 4, 5 or 6 weeks, were determined in ruminally cannulated Holstein and Jersey cows by using the in sacco nylon bag technique. The degradabilities of DM and NDF across breeds differed between the LH harvested after the regrowth periods of 4, 5 and 6 weeks. Increasing the regrowth period of LH from 4 to 6 weeks significantly reduced effective DM degradability (k p = 0.08) from 59.0% to 51.2% and NDF degradability from 30.8% to 21.2%. Crude protein degradability tended to decrease with advancing maturity, with values of 77%, 73% and 74% after 4, 5 and 6 weeks' regrowth, respectively. Effective degradability of DM, CP and NDF did not differ between Holstein and Jersey cows. The results from this study suggest that LH harvested after a shorter regrowth period is of a higher quality in terms of DM, CP and NDF degradability which decreases as the plants mature. <![CDATA[<b>Polymorphism of the <i>GnRHR</i> gene and its association with litter size in Boer goats</b>]]> The polymorphism in the gonadotropin-releasing hormone receptor (GnRHR) gene was detected by PCR single-strand conformational (PCR-SSCP) and DNA sequencing methods in 224 Boer goats. Two single nucleotide polymorphisms (SNPs), G891T and G757A, were found in the exon I of the goat GnRHR gene and their associations with litter size in Boer goats were evaluated. Association analysis showed that G891T and G757A had significant effects on litter size. In locus G891T, individuals with GT genotype had significantly larger litter sizes compared to GG genotype in the first and third parity. In locus G757A, ewes with GG genotype had significantly higher litter sizes than those of GA in the fourth parity. The present study primarily revealed an association between allele T at 891 locus of the GnRHR gene and high litter size in the first and third parity in Boer goats. These results provide evidence that the GnRHR gene may be significantly correlated with a high prolificacy in goats. <![CDATA[<b>Influence of a newly-synthesised 5-oxo-1,2,4-triazyne derivative on antioxidant indices of blood and performance of turkey hens</b>]]> The aim of the study was to evaluate the influence of a newly-synthesised 5-oxo-1,2,4-triazyne derivative on the antioxidant status and performance of turkey hens. The experiment was conducted on six-week old Big-6 turkey hens, divided equally into four groups (60 birds/group). The treatments were: T0 - control (no triazyne supplement) and T15, T30, T45: 5-oxo-1,2,4-triazyne supplementation at 15, 30 and 45 µg/kg BW/day, respectively. The additive was administered over a period of eight weeks. A two-week break with no triazyne supplementation was given in the middle of that period. The performance indices were body weight, feed conversion ratio and the Index of Rearing Effectiveness (WEO). The antioxidant parameters were superoxide dismutase, glutathione peroxidase and catalase activity in erythrocytes and copper, iron and zinc concentrations in plasma. None of these measurements were affected by any of the supplementation treatments. However, after four weeks the supplementation of the 5-oxo-1,2,4-triazyne derivative caused a significant increase in superoxide dismutase activity in the erythrocytes of the hens, and after 10 weeks, only at the highest dose of supplementation. After four weeks of supplementation, the group that received the highest dose of the additive showed an increase in total antioxidant potential (FRAP) in the plasma as well as in its components, i.e. uric acid and vitamin C. After 10 weeks of supplementation a decrease was recorded in the FRAP value, as well as in uric acid, ascorbic acid and Cu concentrations in plasma. The observed growth of enzymatic and non-enzymatic antioxidants may indicate a mobilization of the antioxidant defence system. However, at the end of experiment, the significant decrease in the plasma concentration of the non-enzymatic antioxidants suggests that the body reserves were depleted. <![CDATA[<b>The protein dispersibility index in the quality control of heat-treated full-fat soybeans</b>: <b>an inter-laboratory study</b>]]> There are a number of laboratory methods that could be used to estimate the adequacy of full-fat soybean (FFSB) heat treatment. The protein despersibility index (PDI) has been claimed to have the most constant response to the heating of FFSBs. In this study, the PDI method has been subjected to an inter-laboratory test, including the participation of eight laboratories. Seven FFSB samples were processed by dry extrusion at temperatures ranging from 110 to 164 ºC and analysed on the PDI. Processed FFSB samples were also assessed in a growth trial of broilers. The analysis of the FFSBs by the PDI method generated adequately-processed FFSB values of between 8.49% and 10.3%. Values above 10.3% described under-processed and below 8.49% over-processed FFSBs. The PDI method generated a good repeatability limit of 2.1%, but the reproducibility limit (7.73%) was too wide when taking into account the narrow range (8.5 - 10.3%) for adequately heat-treated FFSBs. Despite its simplicity and initial indications that it might be the best indicator of FFSB heat treatment, the PDI method did not prove that in this inter-laboratory study. <![CDATA[<b>Effects of dietary turmeric supplementation on plasma lipoproteins, meat quality and fatty acid composition in broilers</b>]]> An experiment with 200 day-old male broiler chickens was conducted to investigate the effect of the dietary supplementation of turmeric rhizome powder (TRP) on plasma lipoprotein concentrations, and the meat quality and fatty acid composition of the thigh muscle of the broilers. The four treatments were 0% (F.TRP), 0.25% (L.TRP), 0.50% (M.TRP) and 0.75% (H.TRP) TRP in the diets. The pH and the fat, protein, dry matter and ash concentrations of thigh meat did not show significant differences between treatments. There were no significant differences between treatments in the concentrations of plasma triglyceride, total cholesterol and very low-density lipoprotein-cholesterol (VLDL-c) at three weeks, and for plasma low-density lipoprotein (LDL-c) at three and six weeks of age. At week 6, the M.TRP- and H.TRP-fed birds showed lower plasma triglyceride and VLDL-c concentrations than the birds in the other treatments. At weeks 3 and 6 the concentration of plasma high-density lipoprotein-cholesterol (HDL-c) of the M.TRP- and H.TRP-fed birds was significantly higher than that of the F.TRP-fed birds. At week 6, the H.TRP-fed birds had significantly lower concentrations of saturated fatty acids (SFA) in the thigh and total cholesterol in the plasma than the F.TRP-fed birds and the other birds. Moreover, a significantly higher thigh vaccenic acid concentration was indicated for the H.TRP-fed birds compared with the L.TRP- and F.TRP-fed birds. In orthogonal comparisons, TRP consumption reduced the concentration of plasma triglycerides and dry matter of thigh meat, as well as triglyceride, palmitic acid and total SFA concentrations, but increased the thigh meat protein and plasma HDL-c concentrations significantly, compared with the control. In conclusion, supplementation of TRP in broiler chickens diets can decrease the concentrations of SFAs and triglycerides in thigh meat and improve the meat quality as a result.