Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 52 num. 3 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Composition, nitrate and nitrite levels, and antioxidant activity of milk from agroecological and conventional systems</b>]]> Agroecological dairy production systems are gaining attention worldwide. However, few studies have compared the quality of bovine milk produced in these systems with that produced in conventional dairy production systems. In view of the different farming practices, it was expected that milk quality would differ between systems. This study aimed to compare the quality of milk produced by cows raised in the two systems. Twelve conventional farms and 10 agroecological farms were evaluated. Milk samples were analysed for chemical composition, somatic cell count, nitrate and nitrite levels, and total antioxidant capacity (TAC), which was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. Mean somatic cell counts (SSC) were high for both agroecological systems (2.31 SCC/mL (log10)) and conventional systems (2.42 SCC/mL (log10)). Nitrate levels of milk in agroecological and conventional systems were 0.15 ± 0.03 and 0.17 ± 0.02 mg/L, and nitrite levels were 0.05 ± 0.03 and 0.07 ± 0.02 mg/L. The DPPH radical scavenging activity levels were 6.31 ± 0.55% and 6.64 ± 0.44% for agroecological and conventional systems. According to the ABTS method, TAC values were 6.63 ± 0.28% and 6.48 ± 0.20% for agroecological systems and conventional systems. Thus, although these systems adopted different farming practices, no significant differences were observed in milk composition, SCC, nitrate, nitrite, and TAC. <![CDATA[<b>Efficacy of <i>Tragopogón graminifolius </i>medicinal powder as an inulin source for laying hens</b>]]> In an experiment, the efficacy of Tragopogon graminifolius (TG) plant powder as a medicinal supplement for laying hens was investigated. A total of 192 Hy-line (W36) hens that had been laying for 52 to 63 weeks, were used. They were allocated to four replicates of four treatments (12 birds per in each replicate) in a completely randomized design. Diets were formulated to contain 0%, 2%, 4% and 6% TG powder. Dietary augmentation with TG powder affected the production and blood indexes of laying hens significantly. Egg weight, egg production percentage, egg mass and feed intake were greatest and feed conversion ratio, high yolk colour index, and Haugh unit were best when the hens were supplemented with 6% TG powder. Eggshell thickness decreased when this high level of TG powder was used. The lowest blood white cell count was observed with 2% TG in the diet. The TG levels did not change the blood indexes meaningfully. Based on these results, the provision of TG to laying hens at up to 6% of their diet improved the production traits. <![CDATA[<b>Proportions of protein and concentrate in diets for buffaloes and cows affect neutral detergent fibre degradability</b>]]> The study was designed to compare low and high levels of protein, namely 90 and 147 g/kg of dietary dry matter, and to evaluate the effect of concentrate proportions on the in situ digestion kinetics of neutral detergent fibre in buffaloes and cows fed a low protein diet at maintenance intake level. In the first experiment, heifers and lactating females were offered a high protein diet. In the second, the performances of buffaloes and cows were compared when fed diets with low and high proportions of concentrate at low dietary protein level. At higher protein supply, the heifers showed a 6% unit increase in neutral detergent fibre degradability (NDFD) compared with lactating animals. Similarly, at a higher level of concentrate proportion, an 8% unit increase was observed in NDFD. In both experiments the comparison of buffaloes and cows was non-significant for NDFD. Those data that were pooled against the stage of development of both experiments for protein levels depicted a 13% unit increase in NDFD at high protein level compared with low level. At maintenance intake level, a high dietary crude protein or concentrate supply improved the in situ NDFD of tropical forages in buffaloes and cows, owing to the enhanced intake of NDF from concentrate and better synchronization of protein and energy availability in the rumen. <![CDATA[<b>Effect of ferulic acid on growth, digestibility, digestive enzyme activity, immunity and antioxidant status of broilers</b>]]> This study was conducted to evaluate the effects of ferulic acid (FA) on the growth, nutrient digestibility, digestive enzyme activities, immunity and antioxidant status of broilers. Ninety-six one-day-old male Arbor Acres broilers were randomly divided into two groups with six replicates of eight birds each, including control group (CON) and FA group (80 mg/kg diet). The experiment included starter (days 1-21) and finisher (days 22-42) phases. Compared with CON, FA group had higher average daily weight gain (ADWG) and lower feed to gain ratio (F:G) in the starter phase, and higher average daily feed intake (ADFI) in the finisher phase. The digestibility of dry matter (DM), organic matter (OM), crude protein (CP) and ether extract (EE) were higher in FA-fed broilers in days 19-21, but DM, OM and EE digestibility were lower in days 40-42. Ferulic acid treatment increased duodenal trypsin and jejunal amylase activity on day 21, but decreased duodenal trypsin, chymotrypsin activities and jejunal lipase activity on day 42. FA supplementation increased serum immunoglobulin M (IgM) and tumour necrosis factor-α (TNF-α) concentrations on day 21. Ferulic acid-fed broilers had greater hepatic glutathione peroxidase (GSH-Px) activity and lower serum malondialdehyde (MDA) level on day 21. On day 42, the serum superoxide dismutase (SOD) activity, hepatic SOD and GSH-Px activities was decreased in FA group. In conclusion, FA as an exogenous antioxidant at dosage of 80 mg/kg diet enhanced growth performance via improvement of digestive enzyme activities, immunity and antioxidant status of broilers in starter phase. <![CDATA[<b>Predicting feed intake from weaning to maturity in South African sheep reared on high-energy grain-based diets</b>]]> Feed intake models seldom take breed differences into account. This study investigated various approaches to describing and predicting the feed intake of certain breeds (Dohne Merino, Dormer, Dorper, Meatmaster, Merino, South African Mutton Merino (SAMM) and White Dorper). On weaning at 90 days old, four ram and four ewe lambs from each breed were housed under feedlot conditions and reared on a high-energy concentrate-based diet until they reached maturity at about 12 months. Bodyweight and feed intake were recorded weekly. Daily dry matter intake was modelled with bodyweight for each breed using a quadratic function. Feed intake increased to a peak and then tended to decrease as lambs neared maturity. Dormer lambs had the highest peak intake (2202.02 g/day) and Merinos the lowest (1558.8 g/day). However, this model accounted for less than 50% of the variation in the groups. Linear regressions of percentage intake of bodyweight (R² = 0.732) and cumulative feed intake with bodyweight (R = 0.941) were deemed more reliable in predicting voluntary feed intake. The change in feed conversion ratio was modelled with an exponential relationship. At 75 kg live weight, Dormer rams had the highest feed conversion ratio (20.44) and SAMM rams the lowest (6.48). Generally, lambs with larger frame sizes (Dormer, Dorper and SAMM) presented higher feed intakes at a given bodyweight than smaller-framed breeds. Dorper rams and SAMM lambs proved to have better lifetime feed efficiency than the earlier maturing breeds. <![CDATA[<b>Components and specific gravity of colostrum from Anatolian buffalo cows and effects on growth of buffalo calves</b>]]> This study aimed to determine the relationship between specific gravity (SG) of colostrum and its components, namely dry matter, fat and protein, on the growth of Anatolian buffalo calves. The study used 62 Anatolian buffalo cows and their calves (32 females and 30 males). The SG of the colostrum was measured with a colostrometer™, and the components were analysed with a milk analyser after calving. A single value for analysis was obtained by taking the arithmetical mean of the SG values of the colostrum two hours after birth. The values were classified as below average (Group 1: <1.070 g/ml) and above average (Group 2: &gt;1.070 g/ml). All calves were weighed with an electronic scale at birth and on days 15, 30, 45, and 60 afterwards. Body measurements were recorded at these times. Calves that received high SG colostrum were heavier on days 15 and 30. The chest girth measurements of Group 2 were greater at all ages. At days 30, 45, and 60 after calving, Group 2 had greater wither heights as well. Thus, Group 2 realized greater growth during the neonatal period compared with Group 1. Feeding calves with high SG colostrum is important to obtain adequate immunity and to increase growth. <![CDATA[<b>Metabolizable energy requirements, dry matter intake and feed selection of sable antelope <i>(Hippotragus niger)</i></b>]]> The large animal unit, grazing unit, and browsing unit methods for determining carrying capacity of wildlife use only metabolic weight as a factor to determine the energy requirements of game, whereas the large stock unit method uses metabolic weight and energy requirements of the animal at a specific well-defined physiological production stages. The metabolizable energy requirement in megajoules per day (MJ ME/day) was regressed on weight in kg using a log-log transformation to ascertain whether the large animal unit method was suitable for defining and determining the ME requirements of game. The resulting equations were used to compare the calculated ME and large stock unit values with the published values. Six of the seven categories had values higher than 0.75 with R² values of >0.99, the exception being calf/lamb data with a value of 0.742 with an R² = 0.97. The physiological production stages that were analysed were calf/lamb, young dry cow/ewe, mature dry cow/ewe, young cow/ewe with calf/lamb, mature cow/ewe with calf/lamb, young bull/ram, and mature bull/ram. These results indicated that metabolic weight was neither conceptually correct nor sufficiently accurate to calculate ME requirements for game, confirming the acceptance of the alternative hypothesis. Therefore, the large animal unit (metabolic weight method) cannot replace the large stock unit (metabolizable energy method). The derived log-log transformation equation provided a more accurate method for determining the metabolizable energy requirements and dry matter intake values for sable antelope (Hippotragus niger) and other game species. <![CDATA[<b><i>Sapindus rarak </i>microparticles in feed and drinking water as a substitute for anticoccidials and antibiotics in broilers</b>]]> This study compared the effects of Sapindus rarak microparticles (SRMs), provided through feed or drinking water, with commercial anticoccidial and antibacterial agents. The goal was to determine which would reduce Eimeria sp. oocysts and Escherichia coli populations and improve chicken performance. Three hundred seventy one-day-old Ross broilers were randomly assigned to seven treatment groups with replicates of nine birds each. The birds were reared for 28 days. The T1 group served as a control; T2 was provided anticoccidial/COXI at 2.5 g/L in the drinking water; T3 was fed antibacterial Zn-bacitracin at 0.5 g/kg feed; T4 and T5 were fed SRMs at 0.63 g/kg and 1.25 g/kg feed, respectively; and T6 and T7 were provided SRMs at 0.3 g/L and 0.63 g/L in the drinking water, respectively. Bodyweight, feed consumption, feed conversion, oocysts per gram faeces (OPGs), E. coli number, and mortality were recorded. The results showed no significant (P > 0.05) difference between the treatments on broiler performance, OPGs, and E. coli numbers. Mortality during the study was only 0.53%. Thus, SRMs provided at levels up to 1.25 g/kg of feed ANDWERE 0.63 g/L of drinking water were not significantly different from COXY and Zn-bacitracin in affecting broiler performance, and in reducing OPGs and E. coli numbers. <![CDATA[<b>Enteric methane emission estimates for cattle in Ethiopia from 1994 to 2018</b>]]> The objective of this study was to estimate enteric methane emissions of the Ethiopian cattle population using the Intergovernmental Panel on Climate Change (IPCC) Tier 2 approach. A comprehensive literature review was undertaken to obtain country-specific livestock activity data required to estimate emission factors using the Tier 2 method. Indigenous multi-purpose breeds in the mixed crop-livestock and pastoral/agro-pastoral production systems represent more than 96-97% of the cattle population, and the remainder are specialized dairy breeds. Mean enteric emissions factors from 1994 to 2018 for cattle sub-categories ranged from 3.4 kg to 74 kg methane/headgear for calves older than six months and adult cows in production systems, and from 5.2 kg to 57 kg methane/head/year and 6 kg to 64 methane/head/year for calves less than six months and adult cows in the mixed crop-livestock and pastoral/agro-pastoral production systems,. The national average emission factor for dairy and multi-purpose cows was 74 kg methane/head/year- and 60 kg methane/head/year, across the time series. The current study is the first of its kind for Ethiopia, relying on country-specific animal performance data. It is expected to contribute to an improved national greenhouse gas inventory and provide a basis for better quantification of mitigation targets. Uncertainty of enteric methane emission estimates could be further reduced in the future with more complete data on cattle populations, animal performance and feed characterization. <![CDATA[<b>Impact of chitosan oligosaccharide and valine supplementation on blood biochemical profile of broilers</b>]]> It was hypothesized that dietary supplementation of chitosan oligosaccharide (COS) and valine will ameliorate the biochemical profile of Ross 708 broilers between days 21 and 42 after hatching. To investigate this hypothesis, 480 male broilers were randomly placed in eight treatment groups with two dietary levels of COS (C1: 100 mg/kg and C2: 150 mg/kg) and four dietary levels of valine (V1: 0.57%, V2: 0.72%, V3: 0.87% and V4: 1.02 %) with three replicates having 20 birds in each. The blood samples for serological and haematological profiles were collected and analysed at the age of 42 days to evaluate the effects of supplementation. Serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) decreased with the lowest response values when birds were supplemented at V3 at both C1 and C2. Serum triglycerides (TG) and cholesterol (CHO) levels reduced linearly with increasing supplemental levels of valine at both regimen of COS with the lowest values of 61.07 ± 1.12 and 125.33 ± 1.40 for diet supplemented at V4 and C2, respectively. Serum uric acid (UA) and total proteins (TP) increased linearly with increasing supplemented levels of valine at both C1 and C2. There was a linear increase in total leucocyte count (TLC) and red blood cell (RBC) count for increasing supplemental levels of valine at both C1 and C2. An interactive effect of COS and valine was observed for the changes in ALT, albumin (ALB), TLC and haemoglobin (Hb). In conclusion, COS and valine supplementation significantly affected the liver, renal, lipid and haematological profiles of broilers. <![CDATA[<b>Horn growth characteristics of sable antelope <i>(Hippotragusnigerniger) in </i>South Africa</b>]]> A study of horn growth characteristics of sable antelope in South Africa investigated the environmental effects of sex, calving year and season on horn development for animals up to 50 months old. Horn growth characteristics were assessed in the age categories of 0 to 15, 15.1 to 36, and 36.1 to 50 months. The growth rate (cm/day) of horn length differed significantly between male and female sable antelope in all age categories. The horns of males grew by 0.89 cm/day and females by 0.68 cm/day between 0 and 15 months. Between 15 and 36 months, horn growth was 0.079 cm/day for males and 0.042 cm/day for females. Between 36 and 50 months horn growth was 0.044 cm/day for males and 0.015 cm/day for females. The base circumference differed significantly between the sexes only between 0 and 15 months, when it was 0.026 cm for males and 0.014 cm for females. The number of horn rings did not differ between sexes. Thus, there was rapid initial growth for both males and females, with the horn growth of females slowing noticeably once they reached sexual maturity. Supplemental feeding regimes introduced on most farms affected horn growth traits positively, resulting in longer horns at maturity. <![CDATA[<b>Seasonal performance and behaviour of Nellore cattle in integrated crop-livestock systems</b>]]> The first objective of this study was to assess Marandu palisade grass in an integrated crop-livestock system (ICL), and two integrated crop-livestock-forest (ICLF) systems. The first ICLF had a single row of eucalyptus (ICLF-1L) and the second had three rows of eucalyptus (ICLF-3L). The second objective was to assess the performance, behaviour, and thermal comfort of Nellore cattle in these systems during summer and winter. The data were collected for two years after the systems were implemented. Sixty Nellore cattle were used. Dry forage mass (DFM) was similar in all systems with a higher percentage of leaves observed in ICLF-3L in winter compared with ICL. Forage in the ICLF-1L and ICLF-3L systems contained more crude protein (CP) than ICL. The radiant thermal load was lower for ICLF-1L and ICLF-3L, with a lower globe temperature in ICLF-3L. The stocking rate was lowest for ICLF-3L. Two years after the systems had been established, the trees provided low density shade and implementing the ICLF-1L and ICLF-3L systems improved the CP content of the grass without changing the levels of DFM and performance of the cattle. The trees reduced the total thermal energy exchanged between the animal and the environment, improving thermal comfort, but did not influence cattle behaviour or their haematological parameters.