RESUMO
The experiment investigated the influence of forage drying methods on the dry-matter digestibility of foliage from Cajanus cajan varieties (ICEAP 00557, ICEAP 01514 and CIMMYT100/01). These leaves were harvested at week 20 of growth and either oven- or shade-dried and analysed for chemical components and rumen degradability. Three rumen fistulated lactating Holstein cows (430 ± 18 kg live weight) were used to evaluate ruminal degradation kinetics using in vitro and in sacco procedures. Samples were incubated for 0, 4, 8, 12, 24, 30 and 48 h in vitro (IV DaisyII) procedure. In the in sacco procedure, samples were incubated for 0, 4, 8, 12, 24, 30 and 48 h in the rumen of cows. Dry matter disappearance (DMD) data for both measures were fitted to the equation Y = a + b (1 - e -ct ), where b is the slowly degradable fraction and c is the degradation rate constant, to approximate rumen degradability characteristics of varieties. Shade dried leaves contained higher crude protein (CP) (P < 0.05) than oven dried leaves. Oven drying method increased (P < 0.05) neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) content of varieties. However, shade drying method gave the higher concentration of NDIN and ADIN. Drying technique had no effect (P > 0.05) on ash, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) of varieties. Drying method did not affect (P > 0.05) calcium (Ca) and phosphorus (P) concentration in the forage dry matter. Drying method had no effect (P > 0.05) on b and c of all varieties during in vitro procedure. However, shade-drying method increased (P < 0.05) b and c of all varieties during in sacco procedure. It was concluded that shade-drying, in contrast to oven-drying, would be the most suitable method as it improves the nutritive value of the forage for ruminants.
RESUMO
The effects of high thermal stress on serum protein metabolites, milk production of transition dairy cows in semi-arid areas in South Africa were evaluated. Forty, ± 8 months pregnant, Jersey heifers (± 26 months) in zero grazing management were selected during summer from two semi-arid communal areas. Summer thermal-humidity index (THI) of the areas were THI-1 (72-83: extreme caution) and THI-2 (75-87: danger). Blood samples were collected (21 days pre-partum, and 21 and 75 days post-partum) and analysed for serum protein metabolites. Milk yield was recorded daily and samples collected for milk fat, protein, lactose and urea nitrogen analysis. Heifers in THI-2 had lower (P < 0.05) total serum proteins, albumin and blood urea nitrogen than THI-1. Post-calving, cows in THI-1 had higher (P < 0.05) TP (73.4 vs 67.9 g/l) and BUN (4.61 vs 3.77 mmol/l) at 21 DIM, and lower (P creatinine at 21 and 75 DIM than THI-2 group. Milk yield, fat and protein in THI-2 were all lower (P < 0.05) than THI-1 21DIM. The results confirm that heat stress affects utilisation of nutrients in transition dairy cows.
