Selection, intake and excretion of nutrients by Scottish Highland suckler beef cows and calves, and Brown Swiss dairy cows in contrasting Alpine grazing systems

Abstract

SU MMARYNutrient intake, digestibility and live-weight changes were compared for groups of grazing cattle on two Swiss Alpine pastures in different regions (R1 and R2 ; both >1500 m above sea level) during 2 years (1997 and 1998). The R1 site was an improved pasture, while R2 was an unimproved pasture of poor nutritional quality. Replicated over 2 years, R1 groups comprised four Scottish Highland suckler cows together with their calves and four Brown Swiss dairy cows (17 . 8 kg/day milk) kept at high stocking rates (approx. 7 cows/ha) in short rotations (intensive management system). R2 groups comprised four Highland cows with calves managed at low density (approx. 0 . 4 cows/ha) and setstocked (extensive management system). Grazing seasons lasted 77 days at R1 and 127 days at R2. Intake, digestibility and faecal excretion were estimated by the slow-release alkane indicator method. Average dry matter intakes in kg/day and g/kg W 0 . 75 /day (in parentheses) were 17 . 4 (151) for dairy cows at R1 and, significantly lower, 12 . 7 (133) and 11 . 1 (111) for beef cows at R1 and R2, respectively. Herbage dry-matter intake of calves was 1 . 2 kg/day at both locations. Calf weight gains measured over 77 days (0 . 69 kg/day) were similar at the two sites and thereafter declined only slightly at R2. The N content of the herbage selected was similar in the two regions, but in other respects the herbage at R2 was of significantly poorer nutritive quality as indicated by the lower digestibility of organic matter and neutral detergent fibre at R2 compared with R1. Through feed selection, nutrient intake by beef cows was sufficient to gain weight. In contrast, dairy cows at R1 lost on average more than 50 kg of weight. Calculations were made and discussed regarding N utilization and urinary N loss, and measured faecal N and mineral excretion to allow a quantitative assessment of nutrient returns to the sward. We conclude that Highland beef cattle make poorer use of improved Alpine pasture than dairy cows though they utilize pastures of poor nutritive quality under extensive management without loss of productivity.

Forage intake and botanical composition of feed for cattle fed Brachiaria/legume mixtures

“…If it is assumed that the total N in the animal carcass is 2.5% of the live weight (Scholefield et al, 1991) then the total N gained by the animals each day should be 8.8 g/head/day. So the total N excreted in urine should be the difference between the N consumed and the N excreted as faeces and that accumulated in the LWG (Berry et al, 2002). When working in the field situation it is possible using external markers to estimate faecal production, and if the digestibility of the acquired forage can be measured, or estimated, then total dry matter intake can be calculated.…”

Foraging behaviour and occupation pattern of beef cows on a heterogeneous pasture in the Swiss Alps

“…As expected for a rather extensive breed, this suggests that the Hérens cows were able to cover their protein and energy requirements, even though the nutritive value of the herbage on offer decreased over the season. The CP content of the consumed forage, which showed almost no variation over the three rotations, reflects selective grazing, which plays an important role in maintaining a sufficient N supply (Berry et al, 2002). Cattle also selected a diet that lowers cell wall contents to compensate fibre increase in the forage on offer during the season.…”

“…between 7.00 and 19.00 h. The collecting time for each sample lasted for about an hour. Picking was carried out according to the procedure described by Berry et al (2002), which consists in standing very close to the animals (next to the cows' heads) in order to collect the same plant species like those selected by the cows. In this way, it can be assumed that the collected material accurately reflected selected herbage.…”

Vegetation patterns maintained by cattle grazing on a degraded mountain pasture

“…The climate is Insubrian, with a mean ambient air temperature during the grazing season (June-October) of 13 °C and a mean monthly precipitation of 300 mm (Berry et al 2002). A substantial part of the annual precipitation falls in a few extremely intense rain events than can cause severe soil erosion (personal observation of the authors).…”