Endocrine regulation of metabolism in sheep given kale (Brassica oleracea) and ryegrass (Lolium perenne) – clover (Trifolium repens) fresh-forage diets

Abstract

1. Diets of fresh kale (Brassica oleracea) and ryegrass (Loliumperenne) -clover (Trifolium repens) herbage were fed to growing sheep in three experiments. In Expts 1 and 3 the sheep were confined indoors and fed at hourly intervals, and all were given supplementary iodine to counteract kale goitrogens. Lambs grazed the two forages for 24 weeks in Expt 2, with and without intramuscular injections of iodized oil. The kale and herbage contained respectively 11 and < 0.1 g S-methyl-L-cysteine sulphoxide (SMCO)/kg dry matter (DM) and values for readily fermentable: structural carbohydrate (CHO) were 3.1 and 0.8, respectively.2. Blood samples were withdrawn from indwelling catheters (Expts 1 and 3) or venipuncture (Expt 2) and the plasma analysed for a range of hormones using radioimmunoassay procedures. Glucose irreversible loss (GIL) was measured in Expt 1 using primed continuous infusions of ~-[U-~~C]glucose. Samples of adipose tissue were removed from the shoulder area in Expt 3, and rates of ~-[U-'~C]glucose and [U-"C]acetate incoporation and oxidation were measured in vitro, together with the rate of glycerol release.3. In the presence of supplementary I,, kale feeding was associated with an elevation in plasma concentration of free thyroxine (TJ. Regardless of I, supplementation, sheep fed on kale had much higher plasma growth hormone concentrations than sheep fed on ryegrass-clover herbage, and this was accompanied by reduced plasma somatostatin concentrations.4. Plasma insulin and glucagon concentrations were similar for sheep fed on the two diets; GIL tended to be slightly but not significantly greater (9.4%) for sheep fed on kale than for those fed on ryegrass-clover herbage.5. Kale feeding was associated with increased uptakes of acetate and glucose into adipose tissue, reduced rates of oxidation of both substrates and no difference in rate of glycerol release. Each 1 nmol increase in glucose uptake was associated with 8.7 nmol acetate uptake ( P < 0.001).6. It is proposed that ruminants counteract protein inactivation, caused by production of dimethyl disulphide from SMCO in the rumen, through increasing circulating concentrations of growth hormone and T,, which then stimulate synthesis of replacement body proteins.The feeding value of herbage has been defined as the animal production response to grazing a defined forage, and is a function of both voluntary dry matter (DM) intake and nutritive value: DM eaten (Ulyatt, 1973). Kale (Brassica oleracea) diets are unique in containing much higher values of readily-fermentable : structural carbohydrate (CHO) than normal ryegrass (Lolium perenne)-clover (Trifolium repens) herbage (3.0 v. 0.8), and also containing the free amino acid S-methyl-L-cysteine sulphoxide (SMCO) which is absent from other forage species (Barry et al. 1 9 8 4~) .SMCO in brassica diets is fermented by rumen bacteria to dimethyl disulphide, which inactivates proteins through blocking sulphydryl groups (Fig. l ) , and is the cause of haemolytic anaemia associated with feeding brassica diets to

Effect of three forages and two forage allowances offered to pregnant dry dairy cows in winter on periparturient performance and milk yield in early lactation

“…Cows offered grass silage displayed the greatest increase in body condition score pre‐partum compared to those offered kale and fodder beet (0·37 vs. 0·09 and 0·22 units respectively). However, assuming the ME concentration of kale to be 12·5 MJ kg −1 DM (Barry et al. , 1985) and that of fodder beet to be 13·7 MJ kg −1 DM (Fitzgerald, 1983), offering treatments KH and FBH in situ (outdoors) should have resulted in greater estimated ME intakes relative to those offered treatment GSH (indoors).…”

“…, 1981a) while fodder beet can have DM yields of up to 14 t ha −1 (Fitzgerald, 1983). Forage kale and fodder beet can maintain a high nutritive value over the winter [12·5 MJ ME kg −1 DM (Barry et al. , 1985) and 13·7 MJ ME kg −1 DM (Fitzgerald, 1983) respectively].…”

The effect of sowing date and nitrogen on the dry‐matter yield and nitrogen content of forage rape (Brassica napus L.) and stubble turnips (Brassica rapa L.) in Ireland

“…, 1983, 1984; Rao and Horn, 1986; Gowers and Armstrong, 1994; Jacobs et al. , 2001) while maintaining a high energy value [1·03–1·12 Unité Fourrageré Lait −1 (UFL) kg −1 DM (Jarrige, 1989); 11·5–14·5 MJ Metabolisable Energy −1 (ME) kg −1 DM (Barry et al. , 1985)] over the winter period.…”

The physiological consequences of ingesting a toxic plant ( Diplotaxis tenuifolia ) influence subsequent foraging decisions by sheep ( Ovis aries )

“…Wild rocket, as well as other plants in the Brassicaceae family, presents high content of the sulphur-containing amino acid S-methyl-cysteine sulphoxide (SMCO) [50]. During ruminal fermentation, SMCO is hydrolyzed to dimethyl disulphide (DMDS), a compound that can inactivate proteins by blocking sulphydryl groups [51]. Considering the potential inactivation of wild rocket proteins, and given the fact that plants in the Brassicaceae family typically contain high levels of soluble carbohydrates [52], it is possible to predict an enhanced intake of wild rocket by sheep in response to protein supplementation.…”