Similarities between digits’ movements in grasping, touching and pushing

In order to find out whether the movements of single digits are controlled in a special way when grasping, we compared the movements of the digits when grasping an object with their movements in comparable single-digit tasks: pushing or lightly tapping the same object at the same place. The movements of the digits in grasping were very similar to the movements in the single-digit tasks. To determine to what extent the hand transport and grip formation in grasping emerges from a synchronised motion of individual digits, we combined movements of finger and thumb in the single-digit tasks to obtain hypothetical transport and grip components. We found a larger peak grip aperture earlier in the movement for the single-digit tasks. The timing of peak grip aperture depended in the same way on its size for all tasks. Furthermore, the deviations from a straight line of the transport component differed considerably between subjects, but were remarkably similar across tasks. These results support the idea that grasping should be regarded as consisting of moving the digits, rather than transporting the hand and shaping the grip

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

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 South African Journal of Animal Science Vol.33(2) 2003: 132-14

Selenium (Se) supplementation on the Se status of dairy cows in the Midlands of KwaZulu-Natal

A dose-response trial was conducted with dairy cows on six farms in the Ixopo district of the Midlands of KwaZulu-Natal. Up to 30 cows per farm received a single subcutaneous injection of 5 mL of a long-acting/slow-releasing selenium (Se) supplement containing 50 g Se as barium selenate/mL (Deposel). The same number of matching cows per farm was used as controls. The cows grazed cultivated pastures and received concentrates containing no added Se. Whole blood Se concentrations were determined on day 1 and at ca. three month intervals thereafter. The investigation was conducted for periods ranging from between 300 and 400 days on the different farms. Incidences of retained placenta, metritis, cystic ovaries, mastitis and calf mortality were recorded. Whole blood Se concentrations of the unsupplemented cows ranged from 17 to 90 ng/mL. Accepting that a concentration of >200 ng/mL blood indicates an adequate Se intake, the recorded concentrations suggest that the cows were deficient to marginally deficient in Se. The parenteral Se supplementation at the prescribed dose increased blood Se concentrations by an average of 32.8 ng/mL, but this was insufficient to raise blood Se concentrations to adequate or recommended levels for dairy cows. No significant differences were recorded on the incidence of retained placenta, metritis, cystic ovaries, mastitis and calf mortality. It was concluded that, if not supplemented, dairy cows grazing cultivated pastures in the Ixopo district of KwaZulu-Natal are likely to be deficient to marginally deficient in Se. However, the prescribed dose of 5 mL of the slow-releasing Se supplement was too low to overcome the deficiency. Keywords: Dairy cows; selenium; Ixopo; parenteral supplementation; Deposel South African Journal of Animal Science Vol. 36 (5) 2006: pp.18-2

Potential benefit of trace element supplementation of sheep on a low level of nutrition

A study was conducted to test whether supplementation of trace elements would have any beneficial effect on year-old ewes receiving a submaintenance level of nutrition. The ewes were fed a poor quality hay. The control group received no supplementation (Treatment 1). A solution containing copper (Cu, 5 mg/d), selenium (Se, 1.6 mg/d) and zinc (Zn, 48.2 mg/d) was dosed twice a day to sheep in Treatment 2 while the ewes in Treatment 3 received a double dose of the three elements. Tissue analyses at the end of the 93-day experimental period suggested that the lambs in the control group suffered from a marginal Se deficiency, while the intake of the other elements seemed to be sufficient. Within treatments, weight changes varied tremendously. Therefore, even though differences were not significant, the unsupplemented control group lost weight, while the sheep in the other two treatments maintained their initial body weights during the study. Likewise, the control group tended to have a lower immune response against an injected foreign protein than the supplemented treatments, though differences were not significant. Plasma in the control group showed significantly higher activities of creatine phosphatase and aspartate transaminase than the supplemented groups. This suggested that the supplemented elements protected the body against tissue damage. Although it is traditionally considered that deficiencies in energy and protein, as first limiting nutrients with the highest priority in nutrition, should be overcome before any response to trace element supplementation could be expected, many of the micronutrients are involved in antioxidant activities in the body. Results from this study suggested that positive responses to micronutrient supplementation could be possible if the body is subjected to oxidative stress during submaintenance levels of energy and/or protein nutrition. South African Journal of Animal Science Vol. 36(1) 2006: 20-2

The use of n-alkane markers to estimate the intake and apparent digestibility of ryegrass and Kikuyu by horses

The n-alkane marker (dosed marker, dotriacontane, C32, herbage markers C31, C33 and C35) technique was evaluated for use in feed intake and digestibility studies with horses. The mean retention time of digesta in the digestive tract was determined in horses following a single dose of C32. The n-alkane technique was then employed to estimate dry matter intake and digestibility in horses fed fresh perennial ryegrass (Lolium perenne), fresh Kikuyu grass (Pennisetum clandestinum, Hochst) and Kikuyu hay. The mean retention time of the C32 marker in the horses was estimated to be 27.9 h. On average the C32 had a slightly greater faecal recovery of 0.89 than the odd-chain alkanes (0.80-0.85), though the differences were not significant. The alkane technique, using the n-alkane markers, gave good estimates of dry matter intake, e.g. for fresh ryegrass the measured intake was 8.86?0.23 kg and the estimated intakes from the C31:C32 ratio, 7.9?1.9 kg and from the C32:C33 ratio, 8.3?1.4 kg. However, the effect of the higher recovery of the dosed marker needs further investigation. The estimates of apparent dry matter digestibility corresponded well with measured values, provided the factor for the incomplete faecal recovery of the internal alkanes was included in the calculation. It was concluded that the alkane technique is suitable to estimate feed intake under grazing conditions. However, the proportion of dietary alkanes recovered in the faeces has to be known to obtain an accurate estimate of apparent digestibility. This would be a problem under grazing conditions when faecal grab samples are taken for measuring faecal alkane concentrations. South African Journal of Animal Science Vol.32(1) 2002: 50-5

The viability of the socio-economic sustainability of under developed farmers in the Driefontein area, north west province

Different arguments about the viability of underdeveloped farmers are going around. Many researchers and stakeholders were involved in projects aimed at improving the underdeveloped farmers’ enterprises. Very few of the private or Government initiated projects paid any dividends to those involved. It appears that farmers lack the capability to incorporate the five components (biological viability, resources availability and viability, economic viability, social / community orientated viability and risk factors) necessary to manage a sustainable agribusiness. This study looks atpresent agricultural enterprises, the socio-economic components needed for a sustainable enterprise and how a sustainable enterprise should be managed by underdeveloped farmers. The study area was Driefontein which is situated in the north eastern part of the North West Province (25o55’ E: 25o45’ S). The average yearly rainfall over the period 2000 to 2007 was 325 mm. Of the 218 respondents 27% is involved in animal husbandry and 42% is involved in crop production. The remaining 31% is subsistence farmers and/or are involved within the farming community. The 218 farmers produce a total of 18 t of maize, 20 t sorghum and 7 tsunflower on a total of ± 660ha, which proves the situation to be unsustainable according to the five pillars criteria for sustainable agriculture. The three input parameters representing the highest expenditure levels are fuel (R3 216), seed (R1 794) and labour (R1 335). Given the income they obtained from their crop production it is evident that the profit (per farmer) was R63 (maize), R235 (sorghum) and R64(sunflower) per production season, respectively. The farmers indicated that the main reason for crop losses is drought, and to a minor extent damage caused by birds, stray animals, theft, diseases and pests. Damage caused by incompetency and monoculture practises are not considered a risk. However, if the potential farmers (semi-commercial and share croppers) receive training regarding sustainable agriculture, they will become accustomed to the complicacy regarding managing a sustainable agribusiness and can develop the needed skills necessary to manage asustainable agribusiness

Heritability of drought adaptive traits and relationships with grain yield in maize grown under high plant population

In low-moisture stress areas with unpredictable rain-free season, high-plant population is suggested for screening maize genotypes with tolerance to drought at flowering as alternative to stressed normal plant density. To confirm efficiency of this option, randomly derived 196 S1 lines from A-511 Maize Population were tested at two plant densities in combination with well watered and drought stressed at flowering. In each of the four environments, the S1 lines were grown in 14 x 14 alpha lattice experimental design to estimate: (i) broad-sense heritability of each tested trait; and (ii) relationships between grain yield and drought adaptive traits. The broad sense heritabilities of flowering traits were relatively high across all growing conditions. In contrast, the heritability for number of ears per plant (EPP) increased with increasing plant density and/or drought stress as for yield and most other traits decreased. Besides, significant association of grain yield with its components and flowering traits observed across all growing conditions in the same direction and opposite direction, respectively. Although relationships of yield with the drought adaptive traits increased consistently with increasing stress, it was highly dependent on its components in all environments but only under stress condition on anthesis-silking interval (ASI). In addition to significant expression of desirable parameters for a population improvement in the stress tolerance, ASI and EPP are relatively easily measured on field as compared to other drought adaptive traits. Thus, the strong dependence of yield on both traits and their high heritability in each or combination of the two stresses have confirmed possibility of using them for screening drought tolerant maize under high plant density, specially in areas that lack rain-free season.Keywords: Drought adaptive trait, high plant density, heritabilit

Grasping trapezoidal objects

When grasping rectangular or circular objects with a precision grip the digits close in on the object in opposite directions. In doing so the digits move perpendicular to the local surface orientation as they approach opposite sides of the object. This perpendicular approach is advantageous for accurately placing the digits. Trapezoidal objects have non-parallel surfaces so that moving the digits in opposite directions would make the digits approach the contact surfaces at an angle that is not 90°. In this study we examined whether this happens, or whether subjects tend to approach trapezoidal objects’ surfaces perpendicularly. We used objects of different sizes and with different surface slants. Subjects tended to approach the object’s surfaces orthogonally, suggesting that they aim for an optimal precision of digit placement rather than simply closing their hand as it reaches the object

Effect of method of sample preparation on ruminal in situ disappearance of dry matter and nitrogen in annual ryegrass in dairy cows

The objective of this study was to investigate the effect of method of sample preparation on the degradation kinetics of herbage when applying the in situ technique. Ryegrass (Lolium multiflorum cv. Midmar) was harvested at three and four weeks after cutting and fertilizing with 200 kg nitrogen (N)/ha. Freshly cut herbage was used to investigate the following four sample preparation methods. In trial 1, herbage was (1) chopped with a paper-cutting guillotine into 5-10 mm lengths, representing fresh (FR) herbage; (2) chopped and stored frozen at –20 °C in a chest freezer, representing frozen (FN) herbage; (3) chopped, stored frozen at –20 °C for 12 h followed by freeze drying for 48 h and thereafter milled through a 2 mm screen, representing freeze dried (FD) herbage and (4) chopped and oven dried at 65 °C for 48 h and thereafter milled through a 2 mm screen, representing oven dried (OD) herbage. Prepared samples were incubated in three rumen cannulated, lactating Holstein-Friesian cows. The dry matter (DM) and N loss (%) of the FR, FN, FD and OD herbage differed significantly at 0 and 5 hours incubation but not at 24 or 48 hours. Sample characteristics (particle size, wet or dry sample) clearly influenced the degradability of herbage DM and N. Frozen herbage showed similar degradation characteristics to fresh herbage. In trial 2, ryegrass samples were prepared by the same four methods, but at a standardized particle size, namely, chopped into 5–10 mm lengths. The treatments were: chopped fresh, chopped frozen, chopped freeze dried and chopped oven dried. The N losses differed significantly between treatments for the 0, 5 and 10 hour incubations, but not at the 22 and 46 hour incubation periods. Although the a, b and c fractions differed significantly between treatments, the effective degradability did not differ for fresh, frozen and freeze dried chopped samples. Oven dried chopped samples had reduced effective degradability and are not recommended for determining effective degradability. It is proposed that fresh chopped herbage be used in degradability studies.. Keywords: Ruminal disappearance; degradability; nitrogen; annual ryegrass;dairy cows South African Journal of Animal Sciences Vol. 35 (2) 2005: pp.126-13