African Journals Online
South African Journal of Animal Science

Volume 33, Issue 2, 2003
ABSTRACTS

Derivation of standard lactation curves for South African dairy cows      

Mostert, B.E.; Theron, H.E.; Kanfer, F.H.J.

Abstract: Standard Lactation Curves were derived for South African Holstein and Jersey cows, using 20 herd-, 18 age- and six season classes. Six herd classes were below and 13 above the average production level for both breeds. A standard lactation curve was estimated for each combination of herd-, age- and season class, which resulted in 2 160 curves per trait per breed. Variation in Holstein yields was much larger than that of Jerseys, causing different herd classes to be defined for both breeds. South African cows displayed more variation in yields compared to those of Holstein cows in the Netherlands and Ireland. Season of calving had a pronounced effect on the shape of the Standard Lactation Curve, while the combination of calving age and lactation affected both the shape and level of the curves. Expected yields were therefore higher during the whole lactation in higher compared to lower herd classes.The results of this study form the basis for inclusion of records in progress and short lactations in national genetic evaluation.

Keywords: Calving age, Herd levels, Holstein, Jersey, Standard Lactation Curves, Season of calving

Protein requirements of growing indigenous chickens during the 14-21 weeks growing period

Kingori, A.M.; Tuitoek, J.K.; Muiruri, H.K.; Wachira, A.M.

Abstract: A study was conducted to investigate the growth response of growing indigenous chickens between 14 and 21 weeks of age to diet protein level. The chickens were offered diets ad libitum with 100, 120, 140, 160 and 180 g crude protein (CP)/kg diet. Body weight and feed intake of the birds were recorded weekly. Feed intake and weight gain increased significantly between the 100 and 160 g CP/kg diets where-after they plateau. Feed efficiency measured by feed conversion ratio improved with increasing dietary protein level up to 160 g CP/kg after which there was no further improvement. It is concluded that the CP requirements for these chickens between 14 and 21 weeks of age is 160 g /kg.

Keywords: Indigenous chickens, Protein requirements, 14-21 weeks

The efficacy of a 10% aqueous Neem (Azadirachta indica) seed extract for tick control in Small East African and Toggenburg female goat kids in Tanzania

Schwalbach, M.J.; Greyling, J.P.C.; David, M.

Abstract: The aim of this experiment was to evaluate the efficacy of Neem seed extract (10% water solution) for tick control in goats in the Kilimanjaro area of Tanzania. Eighteen Small East African (SEA) and Toggenburg (TB) female goat kids between 2.5 and 4 months of age were used in the trial. Goats were divided into two similar groups according to age, body weight and breed composition. Ten treated kids (n = 6 SEA and n = 4 TB goats) and eight controls (n = 4 SEA and n = 4 TB goats) were housed in separate pens for shelter at night, but grazed/browsed together during the day on natural pastures infested with adult and immature ticks. The Neem-treated group was hand sprayed weekly (spot treatment) with a 10% aqueous solution of Neem seed extract to the following regions: perineum, udder, ears and sternum at a rate of 10 mL/kg body weight. The control animals were sprayed weekly with water (10 mL/kg body weight) to the same sites. Neem-treated goat kids recorded significantly lower tick numbers than the control animals, with significantly lower tick numbers and tick bite abscesses in the indigenous SEA goats compared to the goats of the exotic TB breed. Significantly higher tick infestations were recorded on both breeds of goats during the summer rainy season. It was concluded that Neem seed extract is effective in controlling ticks in goats. Further studies are necessary to fully understand the effect of Neem on ticks.

Keywords: Ticks, Goats, Neem seed extract

The effect of an essential oil combination derived from selected herbs growing wild in Turkey on broiler performance

Alcicek, A.; Bozkurt, M.; Cabuk, M.

Abstract: One thousand two hundred and fifty sexed day-old broiler chicks obtained from a commercial hatchery were divided randomly into five treatment groups (negative control, antibiotic and essential oil combination (EOC) at three levels) of 250 birds each. Each treatment group was further sub-divided into five replicates of 50 birds (25 male and 25 female) per replicate. The oil in the EOC was extracted from different herbs growing in Turkey. The EOC at 24, 48 or 72 mg/kg diet and an antibiotic at 10 mg avilamycin/kg diet were added to the basal diet. There were significant effects of dietary treatments on body weight, feed intake (except at day 42), feed conversion ratio and carcass yield at 21 and 42 days. Body weights were significantly different between the treatments. The birds fed the diet containing 48 mg essential oil/kg were the highest, followed by those receiving the diets containing 72 mg essential oil/kg, the antibiotic, the negative control and the 24 mg essential oil/kg at day 42, respectively. From 1 to 21 and 1 to 42 days of age, feed conversion ratios were improved significantly by the supplementation with 48 and 72 mg essential oil/kg diet. The feed intakes were significantly different between the treatments at 21 days, but not at 42 days. Supplementation in excess of 48 mg EOC/kg had no additional beneficial effect on body weight, feed intake, feed conversion ratio and carcass yield. The EOC, a feed additive of natural origin, may be considered as a potential growth promoter in broiler production.

Keywords: Essential oil combination, Herbs, Antibiotic, Performance, Broiler

The influence of separate-sex rearing on ostrich behaviour and skin damage

Meyer, A.; Cloete, S.W.P.; Brown, C.R.

Abstract: Separate-sex rearing of slaughter ostriches was investigated as a management strategy to minimize skin damage. Day-old ostrich chicks were divided into three treatment groups; a group of mixed-gender and two single-sex groups, one male and one female. At three months of age, because of the large variation in live weights, the birds were sorted within treatment according to weight. Each gender treatment was represented by six replications and each weight class treatment was represented by nine replications. At slaughter, chest circumference, slaughter weight, carcass weight, skin weight, skin area and skin grading were recorded. The only slaughter trait that was affected by gender treatment was skin weight without fat, with all-male groups having significantly heavier skins than all-female groups. Behavioural observations, carried out at nine and 13 months of age, indicated that aggression was more prevalent in all-male groups compared to all-female and mixed-gender groups. The all-female groups had the lowest levels of aggression. Diurnal time-activity budgets were largely unaffected by the gender composition of the groups. Evaluation of the skins at slaughter showed that kick marks on the area outside of the crown were more prevalent in all-male groups, indicating that increased aggression was associated with increased kicking behaviour which led to skin damage. However, because of the location of the kick marks, skin grading was not influenced. Weight class treatment also affected the prevalence of kick marks. Aggression and kick marks on the skin were generally more pronounced in the groups comprising the heavier chicks, suggesting that body weight may have an important effect on hormone levels and aggressive behaviour. Because of the general lack of improvement in the skin grading of the ostriches due to the increased skin damage in all-male groups when separated, it is concluded that the practice of separate-sex rearing has no definite benefits for slaughter ostrich production and product quality.

Keywords: Separate-sex rearing, Ostrich behaviour, Gender, Skin damage, Aggression

Oviposition and egg quality traits of dwarf and naked neck layers

Garces, A.; Casey, N.H.

Abstract: Oviposition and egg quality traits were studied in dwarf and naked neck layers in Maputo (Mozambique) during a 28-d period at 35 weeks of age. Birds were caged individually in a laying house with natural light and ventilation. Average daylight length during the study was 11.2 hr and minimum and maximum temperature was 19.6 °C and 30.1 °C, respectively. The main results show that the sex-linked dwarfing gene (dw) increased the mean interval and time of oviposition, and reduced the sequence length and rate of lay. A bimodal distribution of oviposition intervals was observed in the dwarf population. No meaningful effect of the naked neck (Na) gene could be seen on oviposition traits. The dw gene also reduced the egg and components weight as well as the height of the albumen. The Na gene was associated with increased yolk weight and reduced albumen height.

Keywords: Naked neck, Dwarf, Oviposition, Egg quality, Laying hens

The response to selection during first lactation on the phenotypic and genetic trends in the Elsenburg Holstein-Friesland herd

Muller, C.J.C.; Botha, J.A.

Abstract: A breeding policy to improve milk production in the Elsenburg Holstein-Friesland herd was adopted in 1984. Cow selection was based on partial (90 days) and completed (300 days) lactation records of 4% fat corrected milk and protein yields during first lactation. Dutch type AI proven bulls as well as young unproven bulls from the herd were used initially. Holstein type bulls with the highest breeding value predictions (BV's) for milk and component yields were used since 1987. The phenotypic and genetic trends in milk yield for first lactation cows of the herd were derived from an animal model analysis conducted by the ARC-Animal Improvement Institute. The phenotypic trend for milk yield in the Elsenburg Holstein-Friesland herd was positive, amounting to 212 kg per year (R2 = 0.88). Regression of average BV's on production year prior to 1984 suggested no change in genetic merit of first lactation cows over that period (R2 = 0.35). Average BV's of first lactation cows in the Elsenburg Holstein-Friesland herd subsequently improved by 92.3 kg/year (R2 = 0.96). This improvement was higher than corresponding genetic change in the national herd over the same period (76.4 kg/year; R2 = 0.98). Rigorous culling of inferior milk producing cows on first lactation records and using bulls with high breeding values for milk and component yields had a marked improvement on the genetic merit of first lactation cows in the herd. This improvement on the genetic merit of first lactation cows in the herd amounted to 1 200 kg milk per cow over the 13-year period it was practiced.

Keywords: Phenotypic change, Genetic change, Selection response, First lactation cows, Milk yield, Holstein-Friesland

Variation in the chemical composition, physical characteristics and energy values of cereal grains produced in the Western Cape area of South Africa

Brand, T.S.; Cruywagen, C.W.; Brandt, D.A.; Viljoen, M.; Burger, W.W.

Abstract: Grain samples were produced at 10 different locations in the Western Cape region of South Africa, on 2.1 m x 6 m experimental plots, over a period of three years. Twenty different cereal grain cultivars were used in the study. A randomised square experimental design with four replicates per sample was used. An area of 1.35 m x 5 m from each plot was harvested during 1994, 1995 and 1996 and the yield was determined. Thousand seed mass (TSM) and hectolitre mass (HLM) were also determined. Samples were analysed for dry matter (DM), ash, crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF) and in vitro organic matter digestibility (IVOMD). Digestible energy values (DE) for pigs were determined with a mobile nylon bag technique, while non-structural carbohydrate values (NSC) were calculated. In the first analysis, cultivars were compared by a one-way analysis of variance, followed by pooling of grain type data. Naked oats had the highest DE value, and the respective values (DM basis) for naked oats, wheat, triticale, 2-row brewer's barley, 6-row feed barley and oats were 18.0, 16.0, 15.8, 14.9, 14.4, and 12.6 MJ/kg DM. The high EE value of naked oats (97 g/kg) might be partly responsible for the high DE value. The 6-row and 2-row naked barley cultivars had the highest IVOMD (946 g/kg and 944 g/kg), followed by wheat (910 g/kg), triticale (905 g/kg), naked oats (899 g/kg), 2-row brewer's barley (882 g/kg), 6-row feed barley (844 g/kg) and oats (671 g/kg). Considerable variation was found between samples within a cultivar for DE and IVOMD. Two-row naked barley had the highest mean CP value (159 g/kg) followed by naked oats (159 g/kg), 6-row naked barley (154 g/kg), wheat (148 g/kg), triticale (146 g/kg), oats (143 g/kg), 2-row brewer's barley (136 g/kg) and 6-row feed barley (135 g/kg) on DM basis. Triticale had the highest yield, with naked oats and barley cultivars having the lowest yield.

Keywords: Cereal grains, Chemical composition, Energy value

Transcervical embryo recovery in Saanen goats

Lima-Verde, J.B.; Lopes Junior, E.S.; Teixeira, D.I.A.; Paula, N.R.O.; Medeiros, A.A.; Rondina, D.; Freitas, V.J.F.

Abstract: In order to study the embryo recovery rate using the transcervical technique in Saanen goats raised in the tropics, 20 donors were submitted to an oestrus synchronisation treatment using intravaginal progestagen sponges for 11 days. On the ninth day of treatment, goats received intramuscular injections of 50 µg cloprostenol and six injections of porcine follicle stimulating hormone (pFSH) at 12-hour intervals. Does in oestrus were mated by Saanen bucks. Donors received an intramuscular injection of 50 µg cloprostenol 24 hours before embryo collection. At this time, the ovaries were observed by laparoscopy to verify the ovulation rate. The embryo recovery was performed six to seven days after oestrus onset by transcervical technique. Goats in which the cervix was not penetrable were submitted to embryo recovery by laparotomy. The recovered embryos were classified according to the International Embryo Transfer Society (IETS) guidelines. Oestrus was observed in 85% of goats. A response to superovulatory treatment was observed in 65% of goats and a mean ovulation rate of 11.5 ± 6.6 was recorded. The cervix was penetrable in 61.5% of goats. In the remaining goats the embryo recovery was performed by laparotomy. The recovery rate was 53.2% and 36.9% using transcervical and surgical methods, respectively. Quanti-qualitative embryo production was similar in both techniques. Embryo recovery by the transcervical technique was shown to be an alternative for collection of embryos in Saanen goats. However, further studies should be done in order to improve both the cervix penetrability and embryo recovery rate.

Keywords: Goats, Embryo recovery, Transcervical technique, Saanen, Tropics, Superovulation

The chemical composition and potential nutritive value of the foliage of four subtropical tree species in southern Africa for ruminants

Lukhele, M.S.; Van Ryssen, J.B.J.

Abstract: The foliage of three Combretum species, C. apiculatum, C. molle and C. zeyheri, as well as that of Colophospermum mopane was collected over a period of two years. The chemical composition, in vitro organic matter digestibility (IVOMD) and the rumen degradability of dry matter (DM) and nitrogen (N) were determined on these samples. Mean values for crude protein (CP) concentration varied from 92 g/kg DM for C. molle to 141 mg/kg DM for C. mopane, the neutral detergent fibre concentration from 323 g/kg DM for C. apiculatum to 392 g/kg DM for C. molle and that of acid detergent fibre from 247 g/kg DM for C. apiculatum to 355 g/kg DM for C. molle. The calcium (Ca) concentration in the foliage was high (8-16 g/kg DM) compared to the phosphorus (P) concentrations of between 0.8-2.1 g/kg DM, resulting in an average Ca: P ratio of 9.3: 1. The foliage contained relatively low levels of sodium (Na), 0.041 g/kg DM, based on beef cattle standards. The IVOMD ranged from 53% for C. mopane to 64% C. apiculatum and the rumen degradability of DM from 78% for C. molle to 94% for C. apiculatum. The DM degradability was substantially higher than that of nitrogen, which varied between 47% for C. apiculatum and 60% for C. zeyheri. It was concluded that the foliage tested would not be suitable sources of N to supplement protein deficiencies in low quality herbage. Furthermore, browsers would require additional sources of P and Na to avoid deficiencies in these elements.

Keywords: Leaves, Combretum species, Mopane, Ruminal degradability, In vitro digestibility, Browse