Scielo RSS <![CDATA[South African Journal of Animal Science]]> http://www.scielo.org.za/rss.php?pid=0375-158920120003&lang= vol. 42 num. 3 lang. <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Effect of dietary starch source on milk production and composition of lactating Holstein cows</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300001&lng=&nrm=iso&tlng= The objective of this study was to evaluate the effects of four sources of starch on milk production and composition, nutrient digestion and blood metabolites of lactating Holstein cows. Four multiparous Holstein cows (708 ± 70 kg of body weight; 83 ± 9 days in milk) were used in a 4 χ 4 Latin square design with 21-d periods. The concentrate portion of the diet contained wheat, barley, maize or potato as the primary source of starch. Intake of dry matter (DM) ranged from 18.7 kg/d to 19 kg/d, and was similar among treatments. Milk production was higher in cows fed the wheat-based diet compared with other diets while the milk fat concentration of the cows fed the maize-based diet was the highest. Milk protein concentration was unaffected by the source of dietary starch. Cows fed the potato-based diet had a lower milk protein, lactose and solid-non-fat yield. Milk yield/kg of DM intake and net energy for lactation (NE L)/NE L intake were higher in cows fed wheat-, barley- or maize-based diets compared with those fed the potato-based diet. Feed nitrogen efficiency was higher in cows fed the maize-based diet compared with the other experimental diets. Total tract apparent digestibility of organic matter, crude protein and ether extract were higher in cows fed the wheat- or maize-based diets compared with those fed barley- or potato-based diets; however, total tract apparent digestibility of neutral detergent fibre and acid detergent fibre were higher in cows fed the wheat-based diet compared with those fed the potato-based diet. These results showed that improved production performance in cows fed the wheat-based diet appeared to be because of greater nutrient digestibility and greater nutrient utilization efficiency. Furthermore, potato starch is not superior to grain starch as a readily available energy source for lactating dairy cows. <![CDATA[<b><i>In ovo</i></b><b> feeding of carbohydrates and incubated at a high incubation temperature on hatchability and glycogen status of chicks</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300002&lng=&nrm=iso&tlng= Eggs from a meat-type breeder flock at 29 and 35 weeks of age were used in two trials to investigate the effects of in ovo feeding of carbohydrates (CHO) and high incubation temperature (37.5 vs. 38.5 °C (HIT)) during days 16 to 21 of incubation on hatchability traits, chick weight at hatch as an absolute value or as a percentage of egg weight (CWTP), hatching time, glycogen concentration in the liver and pectoral muscle, and glycogen index of hatched chicks. The treatments were a non-injected control, a positive control where saline was injected, or saline with a CHO mixture at 50, 100, 150, 200 and 250 mg/egg. The CHO mixture was maltose, sucrose and dextrin in a proportion of 1 : 1 : 8 by weight. As a result of this study, in ovo feeding of CHO increased CWTP without altering hatchability traits. Hatched chicks from eggs injected with 250 mg CHO/egg had a higher liver glycogen content and glycogen index than those of the control treatments. The high incubation temperature reduced chick weight, hatching time, liver glycogen and glycogen index of the hatched chicks. In ovo feeding of 100 and above mg CHO/egg overcame the negative effects of HIT. Hatched chicks from older hens had a lower concentration of liver glycogen and glycogen index than those of younger hens. It was concluded that in ovo feeding of CHO improved the weight and glycogen index of hatched chicks and those of the HIT treatment, and older hens negatively affected the glycogen index of hatched chicks. <![CDATA[<b>Polymorphisms of candidate genes associated with meat quality and disease resistance in indigenous and exotic pig breeds of Vietnam</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300003&lng=&nrm=iso&tlng= The objectives of this study were to analyse genotype distribution and sequence variations of candidate genes putatively associated with meat quality and disease resistance in exotic and indigenous Vietnamese pig breeds. For this purpose, 340 pigs from four indigenous and two exotic breeds were included in the analysis of the polymorphisms of the heart fatty-acid-binding protein (H-FABP), alpha 1 fucosyltransferase (FUT1), and bactericidal/permeability-increasing protein (BPI) genes by the sequencing and PCR-RFLP methods. For H-FABP, 17 single nucleotide polymorphisms (SNPs) were detected in indigenous pig breeds by direct sequencing of a fragment at intron 2 of the H-FABP gene. The mutation T1556C created a new restriction site for the enzyme MspI, which gave rise to new allelic variants in three indigenous pig breeds. In indigenous breeds, the frequency of the favourable alleles a and d at MspI and HaeIII sites of the H-FABP gene were low. Meanwhile, the frequency of the d allele at the HaeIII site in exotic breeds was significantly higher than those of indigenous pig breeds. No mutation was found in the RFLP-fragment of the FUT1 gene of four indigenous pig breeds by sequencing, while in the BPI gene two mutations were detected in the Tap Na breed. The resistant alleles of the FUT1 and BPI genes in the exotic breeds were significantly higher than those of indigenous pig breeds. Among the indigenous pig breeds, the Tap Na breed possessed a higher frequency of the resistant allele G of BPI gene than the remaining breeds. The T1556C mutation at H-FABP may be important for the genetic improvement of intramuscular fat content and breed. Tap Na may be a source of resistant alleles for local ecologies. <![CDATA[<b>Effects of bacterial inoculants and an enzyme on the fermentation quality and aerobic stability of ensiled whole-crop sweet sorghum</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300004&lng=&nrm=iso&tlng= A study was conducted to evaluate the effects of bacterial inoculation and cellulase on the fermentation quality of ensiled whole-crop sweet sorghum (WCSS, Sorghum bicolor L. Moench). The WCSS (323 g dry matter (DM)/kg, 251 g water soluble carbohydrates (WSC)/kg DM, 43 g crude protein (CP)/kg DM and 439 g neutral detergent fibre (NDF)/kg DM) was ensiled with i) no additive (control); ii) Lactobacillus buchneri (LB); iii) Lactobacillus plantarum (LP); and iv) LB+E, a combination of LB and enzyme. These treatments were ensiled in 1 L anaerobic jars for 25 days. The jars were opened on days 3, 7 and 15 to determine pH, while those of day 25 were sampled to determine nutrient composition, fermentation characteristics and aerobic stability. Inoculation reduced pH, butyric acid and ammonia-N and increased lactic acid content in sweet sorghum silage compared with the control. The aerobic stability of WCSS was improved with LB, while it was reduced with the homofermentative LP treatment compared with the control. The LB+E reduced the fibre, but increased residual WSC of silage. The aerobic stability of LB+E silage was lower than LB treated silage. Using enzymes to increase the WSC content of crops that already have high levels of WSC may result in reduced aerobic stability of silage. Further work is needed to evaluate these effects on silage produced on farm scale and on animal production performance. <![CDATA[<b>Effect of butyric acid supplementation and whole wheat inclusion on the performance and carcass traits of broilers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300005&lng=&nrm=iso&tlng= To evaluate the effects of butyric acid (BA) levels and wheat form (WF) on the performance of broiler chickens, 320 day-old Ross 308 broiler chicks were randomly distributed among 32 floor pens. A 4 χ 2 factorial arrangement with four levels of BA (B1: 0 g BA/kg in both starter and grower feed; B2: 2.5 g BA/kg in both starter and grower feed; B3: 2.5 g BA/kg in starter and 1 g BA/kg in grower feed; and B4: 2.5 g BA/kg in starter and 0 g BA/kg in grower feed) and two forms of wheat (whole (WW) vs. ground (GW)) were used. Dietary supplementation with BA had no effect on average weight gain (AWG) or feed conversion ratio (FCR) in the starter, grower/finisher and over whole (0 - 42 d) trial periods. However, birds consumed more when the diet was supplemented with butyrate (B2) relative to the control and other experimental diets during 0 - 42 d, but this increase was not associated with improved AWG or FCR as compared with that of the control. The BA had no significant effect on relative fat pad, gizzard or breast meat, but increased liver weight. The length of the entire gut was augmented by BA and WW feeding. Feeding WW increased the relative weight of the gizzard and liver, but decreased the relative weight of abdominal fat. Two-way interactions were not significant for any of the carcass traits or organ-size parameters except for breast meat, in which a significant interaction was observed between BA and WF. <![CDATA[<b>Steroid implants and markers of bone turnover in steers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300006&lng=&nrm=iso&tlng= Steroidal implants are used extensively in beef cattle management to take advantage of well-documented improvements in growth performance and efficiency. In addition to muscle growth, steroids bring about changes in bone and cartilage formation, hastening bone ageing. The current study was designed to test the hypothesis that recently identified indicators of bone and cartilage turnover could be detected in the peripheral circulation, and that these markers might reflect accelerated ageing effects of the widely used steroidal implants, trenbolone acetate (TBA) and estradiol-Πβ (E2). Thirty-two crossbred yearling steers were given one of four treatments to determine whether these markers of bone turnover could be detected and reflect steroid-induced bone maturity in the periphery: non-implanted controls; 25.7 mg estradiol-Πβ (E2); 120 mg trenbolone acetate (TBA); or 120 mg TBA and 24 mg E2 (T+E). Blood was collected on days 0, 7, 14 and 28 and serum analysed by ELISA for concentrations of IGF-I, osteocalcin, C-terminal telopeptides of Type I collagen (CTX-I) and C-terminal telopeptides of Type II collagen (CTX-II), as markers of the somatotropic-endocrine axis, bone formation, bone resorption and cartilage resorption, respectively. Circulating IGF-I was greater in E2 or T+E treated steers than controls on days 7 and 14. Osteocalcin was unaffected by treatment, but increased from day 0 on days 7, 14 and 28. Treatment did not affect CTX-I. However, CTX-II was elevated in the treated animals as opposed to the controls. Although these markers of bone and cartilage turnover are detectable, results suggest that implant-induced changes are not evident in the circulatory system. <![CDATA[<b>The fatty acid composition of muscles and fat depots of ostriches as influenced by genotype</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300007&lng=&nrm=iso&tlng= Three genotypes of ostrich (South African Black, Zimbabwean Blue Necks and crosses between Zimbabwean Blue Neck males x South African Black females) were used to investigate the influence of genotype on the fatty acid composition of the musculus gastrocnemius and musculus iliofibularis, and abdominal and breast fat depots. Total saturated fatty acids in both the m. gastrocnemius and m. iliofibularis were higher in crosses (36.4% and 35.9%) than in South African Black ostriches (32.9% and 30.4%), whereas mono-unsaturated fatty acids were highest in South African Black ostriches. Total polyunsaturated fatty acids in the m. gastrocnemius were lowest in South African Black ostriches (26.5%) compared with the Zimbabwean Blue Necks (33.2%). Neither the ratio of polyunsaturated to saturated (0.73 to 0.99) nor n-6 to n-3 (1.6 to 2.2) fatty acids were influenced by genotype, although the ratio of polyunsaturated to saturated fatty acids in Zimbabwean Blue Necks was higher in the m. gastrocnemius (0.99) than in the m. iliofibularis (0.73). Differences in individual fatty acids were prominent in the breast fat, and total saturated and mono-unsaturated fatty acids differed between genotypes in both breast and abdominal fat. Only the ratio of polyunsaturated to saturated fatty acids in the fat depots differed between South African Black (0.48) and Zimbabwean Blue Neck ostriches (0.42). The latter ratio was higher in the breast (0.50) than abdominal (0.42) fat in Zimbabwean Blue Necks. These results indicate that crossbreeding of different genotypes of ostriches reared under similar conditions does influence the overall fatty acid profiles of meat and fat. <![CDATA[<b>Effects of dietary L-threonine and <i>Saccharomyces cerevisiae</i> on performance, intestinal morphology and immune response of broiler chickens</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300008&lng=&nrm=iso&tlng= The objective of this study was to investigate the effects of four dietary levels of L-threonine (0, 2.5, 5 and 7.5 g/kg) with or without Saccharomyces cerevisiae (SC) on performance, carcass characteristics, intestinal morphology and immune system of broiler chickens. A total of 360 1-d-old male broiler chicks were randomly allocated to eight treatments with three replicates of 15 birds. The experiment was done at 0 to 3 weeks (as starter phase) and 3 to 6 weeks (as grower phase). Growth performance traits including weight gain, feed intake and feed conversion ratio were recorded at the end of each week. At the end of the experiment eight birds per treatment were killed and carcass analysis was done. Sampling for blood evaluation was done on 7, 28 and 42 days of age. Results of this study indicated that use of SC did not affect feed intake, weight gain and feed conversion ratio in chicks in contrast with the L-threonine. Use of L-threonine improved feed conversion ratio and gain of birds. Carcass traits were not influenced by dietary L-threonine and SC supplements. Use of L-threonine increased the intestinal morphology parameters such as crypt depth and villi height and width in both jejunum and ileum segments. On the other hand, villi height and width and crypt depth increased in both jejunum and ileum segments when dietary L-threonine increased. Effect of SC supplement on intestinal morphology was not significant. Results of CBC (cell blood counts) parameters, such as white blood cells, red blood cells, haematocrit and haemoglobin showed that these parameters were not affected by dietary treatments. Furthermore, the immune response (antibody titre) against Newcastle disease was not affected by SC on both 26 and 42 days of age. However, use of L-threonine influenced the chicks' immune response at 42 days of age. Our results have shown that the supplementation of L-threonine as a source of dietary-threonine in combination with SC improved growth performance and intestinal morphology traits in broilers. <![CDATA[<b>Divergent selection for reproduction affects dag score, breech wrinkle score and crutching time in Merinos</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300009&lng=&nrm=iso&tlng= Merino lines that were divergently selected from the same base population from 1986 to 2009 for their ability to rear multiples were assessed for dag score in autumn and spring, breech wrinkle score, and crutching time. Animals in the Low (L) line had higher dag and breech wrinkle scores and took longer to be crutched than High (H) line contemporaries. Expressed relative to H line least squares means, means of L line individuals were respectively 54%, 65%, 42% and 40% higher for autumn dag score, spring dag score, breech fold score, and crutching time. Gender effects for dag score were inconclusive, as ewe hoggets were more daggy than rams in autumn, with an opposite trend in spring. Shearer (n = 6) also affected crutching times, with an almost twofold difference in mean crutching time from the quickest shearer (27.7 ± 3.1 seconds) to the slowest shearer (49.4 ± 3.7 seconds). The inclusion of dag score and breech wrinkle score as linear covariates in an analysis on crutching time eliminated the effect of selection line. It thus seems that the quicker crutching times of H line animals may be related to line differences for dag score and, to a lesser extent, for breech wrinkle score. <![CDATA[<b>Prediction of 305-day milk yield in Brown Swiss cattle using artificial neural networks</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300010&lng=&nrm=iso&tlng= Artificial neural networks (ANNs) have been shown to be a powerful tool for system modelling in a wide range of applications. In this paper, we focus on the capability of ANNs to predict 305-d milk yield in early lactation of Brown Swiss cattle, based on a few test-day records, and some environmental factors such as age, number of lactation and season of calving. The ANNs that were developed were compared with multiple linear regressions (MLR). The various ANNs were modelled and the best performing number of hidden layers, neurons and training algorithms retained. The best ANN model had input, hidden and output layers of tansig transfer function. The layers had 4, 8, and 1 neurons, respectively. It was determined that the mean predicted values calculated by the ANNs were closer to the real mean values without showing any statistical difference. On the other hand, the predicted mean values calculated by MLR and the real mean values were significantly different from each other. The best prediction in ANN method was seen in 1st, 2nd, 3rd, and 4th test-day records when these were recorded to the system as X1-X8 in the ANN system. In this study, the prediction of 305-d milk yield by ANN gave better results that those of MLR, suggesting that ANN can be used as an alternative prediction tool. <![CDATA[<b>Analysis of troponin I gene polymorphisms and meat quality in Mongcai pigs</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300011&lng=&nrm=iso&tlng= Troponin I is one of myofibrillar proteins required for the calcium regulation of skeletal muscle contraction. The expression of both genes, TNNI1 and TNNI2, in troponin is muscle fibre specific and may affect meat quality traits. In this study, the PCR-RFLP method was applied to genotype 120 Mongcai pigs at three single-nucleotide polymorphisms (SNPs), namely T5174C, C8350A for TNNI1 (EU743939) and C1167T for TNNI2 (EU696779). The two SNPs, T5174C and C1167T, were significantly associated with drip loss48 (measured after 48 h) and compression force, while the second TNNI1 SNP (C8350A) did not show any association with meat quality traits. The results also revealed a relationship between the proportion of IIx muscle fibre and TNNI2. Additional analysis showed a significant association of the TNNI2 SNP (C1167T) with blood glucose. Animals carrying the CT genotype had the highest glucose concentration (93.7 mg/dL). The results demonstrate that TNNI1 and TNNI2 are likely to play a relatively important role in the development of pork quality in Mongcai pigs. <![CDATA[<b>Performance and physiological responses of milk-fed calves to coated calcium butyrate supplementation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300012&lng=&nrm=iso&tlng= The aim of this study was to determine the effects of coated calcium butyrate (CCB) on calf performance and some blood parameters. Sixteen female Holstein calves with a mean age of 3 ± 1 d were divided into two equal groups and fed a milk replacer supplemented with 3 g of coated calcium butyrate (CCB)/day or with no coated calcium butyrate (NCB). The calves had free access to solid feed and water. Body weight was measured at days 3, 12, 24, 36 and 48 (weaning day). Respiratory rate and rectal temperature (within first 4 weeks of life), feed intake and faecal score (during the whole experimental period) were recorded daily. Rumen fluid was taken for volatile fatty acid (VFA) determination on days 33 and 48, and structural growth (rump height, withers height and hip width) was recorded on days 3, 24 and 48. Blood samples were collected on days 1, 12, 24, 36 and 48. Feed intake, average daily gain, feed conversion ratio and structural growth of calves were improved by CCB supplementation. There were no significant differences on rectal temperature, respiratory rate and faecal score between the treatments. Rumen concentration of total VFAs increased and the VFA profile was affected on days 33 and 48 by CCB supplementation. The supplementation of milk replacer of calves with coated calcium butyrate significantly increased serum concentrations of glucose, insulin and β-hydroxybutyrate. Serum concentration of cortisol in the CCB calves was numerically lower than in NCB. In conclusion, supplementation of calves' milk replacer with the coated calcium butyrate could improve calf performance. <![CDATA[<b>The effect of dietary crude protein on the fertility of male broiler breeders</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300013&lng=&nrm=iso&tlng= Reports on the influence of dietary crude protein on male broiler breeder fertility are not consistent, and therefore an experiment was conducted to determine the effect of three isoenergetic diets containing 10.5%, 12.6% and 15% crude protein, respectively, on Ross broiler breeder male fertility from 26 to 41 weeks of age. Feed allocation was the same for each treatment, and was done according to breeder recommendations. Fertility was assessed by determining the number of sperm trapped in the outer perivitelline layer of eggs laid after artificial insemination with a fixed volume of semen collected from 12 males per treatment. Semen concentration, motility and morphology were also determined. Crude protein intake had a significant effect on the rate of decline in fertility post insemination. This resulted in a longer predicted length of the fertile period over all ages when eggs were fertilised with sperm obtained from males that received 12.6% CP diets (14.5 d) than males that received 10.5% and 15% CP (7 and 8.6 d respectively). There was, however, no treatment effect on the measures of live sperm with normal motility or morphology. <![CDATA[<b>Responses of Black Neck ostrich chicks to L-carnitine dietary supplementation during the pre-starter growth period</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000300014&lng=&nrm=iso&tlng= The objective was to determine the growth responses of Black Neck ostrich chicks to different dietary levels of L-carnitine in pre-starter diets. Thirty-two day-old ostrich chicks were randomly divided into four treatments with four replicates, each containing two chicks. All birds received the same basal diet supplemented with 0 (T0, control), 125 (T125), 250 (T250) or 600 (T600) mg L-carnitine per kg. Responses were monitored over three growth phases, 0 - 15, 16 - 30 and 31 - 60 days, the total period being 60 days. T600 had the lowest live weight (LW) and live weight gain (LWG) over the 60-day treatment period. Live weight and LWG values of T125 and T250 did not differ from those of T0. T600 had the worst feed conversion ratio (FCR) during the different stages (0 - 15, 16 - 30 and 31 - 60 days) and over the total 60-day period. Feed intake (FI) was reduced significantly in the T125 and T600 treatments compared to T0 and T250 treatments over the total period. The treatment, T125, showed the lowest FI and FCR responses over the total period, whereas there was no difference between T0 and T250. The results suggest that supplementing the pre-starter diet with 125 mg/kg of L-carnitine can improve the performance of ostrich chicks by decreasing the FCR. In contrast, the suppressive effect of a high inclusion level (T600) might indicate that ostrich chicks are sensitive to a high level of inclusion that could cause adverse effects.