H.J. van der Merwe

Relationships between chemical components of veld herbage and in vitro digestibility and estimated intakes of dry matter and digestible dry matter by sheep and cattle

The relationships between certain chemical components of fertilized and unfertilized Cymbopogon-Themeda summer veld herbage, and its in vitro digestibility and pasture intake by Merino sheep and Simmentaler cattle, were determined in the summer rain area in the Republic of South Africa. The herbage was represented by a wide range of grass species with, according to the literature, different palatabilities. The palatable species were more abundant (P<0.001) on the fertilized veld than on the unfertilized veld. Sheep selected herbage with higher (P<0.01) contents of crude protein (CP) and lower acid detergent fibre (ADF) and neutral detergent fibre (NDF) than that selected by cattle. The in vitro dry matter digestibility (IVDMD) of herbage selected by sheep was also (not significantly) higher. Highly significant (P<0.01) correlations were found between the IVDMD of the pasture and CP content (r=0.817), ADF content (r=−0.858) and CP + ADF content (multiple regression) (4=0.881). The relationship between IVDMD and NDF content, was not significant. Data from unfertilized areas and fertilized areas could be described by a single regression equation for each chemical characteristic. With sheep, dry matter intake (DMI) and digestible dry matter intake (DDMI), respectively, showed highly significant correlations (P<0.01) with CP content (r=0.639 and r=0.714), sulphur (S) content (r=0.796 and r=0.844), ADF content (r=−0.924 and r=−0.922) and NDF content (r=−0.705 and r=−0.729). In the case of cattle, DMI and DDMI, respectively, had highly significant relationships (P<0.01) with CP content (r=0.720 and r=0.788), ADF content (r=−0.806 and r=−0.892) and CP + ADF content (r=0.789 and r=0.900). Data from the unfertilized veld and fertilized veld could be described by a single regression equation for each chemical characteristic. Under the conditions described, some of these relationships can be used fairly reliably for relatively rapid and low cost prediction of potential nutritive value of the summer veld herbage.

A technique for obtaining liver biopsies from mature sheep

Abstract A technique was developed to obtain liver samples with a biopsy needle from live sheep. The biopsy needle (1.5 mm cross-section) was vertically inserted through the tenth intercostal space, on the right hand side of the sheep, 9 cm from the processus spinosus. It penetrated the dorsal section of the liver where a sample was taken by opening and reclosing the needle. On the third attempt, a fresh liver sample weighing approximately 22 mg was obtained. This procedure of liver sampling was successful and showed no side effects on lactating ewes.

Spectrophotometric determination of maleyl-DL-methionine hydrolysis

Abstract The reaction of methionine with maleic anhydride, as well as the rate of hydrolysis at different times and pH levels was investigated in sheep. Only 1.31% of the methionine did not react with maleic anhydride at pH 9.0. After 8 h at pH 2.5, about 76.56% of the maleyl-DL-methionine was hydrolysed. At pH 4.0, 43.14% and pH 5.5 only 4.5% methionine was released. The results suggest that maleyl-DL-methionine may be used to supply methionine in the small intestine of ruminants under both intensive as well as pasture conditions.