H.-R. Wettstein

Effects of feed carbohydrates with contrasting properties on rumen fermentation and methane release in vitro

The RUSITEC system was used to test eight diets where the supplements differed in their main carbohydrate source. The forage-to-supplement ratio was 1:1. The eight feeds characterizing the supplements by specific carbohydrates were oat hulls (modeling lignified fiber), soybean hulls (non-lignified fiber), apple pulp (pectin), sugar beet pulp (hemicelluloses and pectin), guar gum (galactomannan), Jerusalem artichoke tubers (fructan), molasses (sucrose), and wheat (starch). Supplements were iso-energetic and iso-nitrogenous. The dietary carbohydrate fractions were analyzed in detail with a combination of enzymatic and chemical methods. The methane release (mmol g-1 degraded organic matter) increased in the order of diets characterized by oat hulls (0.92), guar gum (0.99), wheat (1.04), soybean hulls (1.13), apple pulp (1.15), Jerusalem artichoke (1.21), sugar beet pulp (1.24), and molasses (1.37). According to multiple regression analysis, diets with high sugar content enhanced methane release while methane...

Contribution of altitude and Alpine origin of forage to the influence of Alpine sojourn of cows on intake, nitrogen conversion, metabolic stress and milk synthesis

A two-factorial experiment was conducted in order to quantify and distinguish the influences of altitude and forage origin on metabolism and milk synthesis of dairy cows kept at Alpine locations. Each of four experimental groups comprised six dairy cows in early to mid lactation which were kept tethered in barns at altitudes of either 2000 (Alpine) or 400 m above sea level (a.s.l.) (lowland). Two groups (Alpine and lowland) received hay ad libitum , a third group kept in the lowlands was pair-fed to the Alpine group and a control group was offered silages and concentrates according to milk yield. Two hay types, with origin either from 2000 or 400 m a.s.l., were offered to all hay-alone groups following a change-over design over three 21-day periods. Transferring cows to high altitude triggered a complex adaptation process, which resulted in depressions of food intake at the beginning of the experiment and changed plasma levels of metabolic traits indicating an energy deficit. On average over the entire experiment, high altitude sojourn elevated plasma β -hydroxybutyrate and decreased plasma glucose levels. Yields of milk and of main milk constituents were not significantly affected, but milk protein content was reduced in both the Alpine and in the pair-fed group. No generally elevated maintenance requirements as a consequence of hypoxia were found. Hay-alone feeding caused a co-limitation of net energy and absorbable protein in both hay types which was almost completely compensated by a reduction of milk yield. The hay of Alpine origin had a lower digestibility and crude protein content than the lowland hay which resulted in changes in blood plasma traits and a further suppression of milk yield and milk protein and lactose contents. Due to the low N content of the Alpine hay, N utilization for milk protein synthesis remained similar to that found with lowland hay, and manure N of these cows contained the lowest proportion of easily-volatile urine N. In conclusion, forage origin in conjunction with diet type seems to explain the major part of the adverse effects that the Alpine sojourn exerts on lactating dairy cows while the effects of hypoxia appear to be of lesser importance.

Comparison of fresh and ensiled white and red clover added to ryegrass on energy and protein utilization of lactating cows

Two respiratory chamber experiments were conducted with dairy cows to compare metabolizable energy and protein utilization when feeding white or red clover with ryegrass. In experiment 1, fresh ryegrass was mixed with fresh white (WF) or red clover (RF) (60/40, on dry matter (DM) basis). Experiment 2 involved similar mixed diets in ensiled form (WS and RS, respectively), and two ryegrass silage diets, without (GS) or with supplementary maize gluten (GS+). Barley was supplemented according to requirements for milk production. Voluntary forage DM intake remained unaffected in experiment 1 and was higher (P<0·01) in experiment 2 for WS than for GS and GS+(128 v. 98 and 106 g/kg M0·75). Within experiments, no treatment effects occurred for apparent nutrient digestibilities, milk yield, and composition. Protein utilization (milk-N/N-intake) was numerically lower on all clover-based diets (0·24 to 0·25) versus GS (0·29). With added maize gluten (GS+), protein utilization decreased to 0·23, indicating that ryegrass silage (plus barley) alone provided sufficient metabolizable protein. Consequently, higher (P<0·01) urinary energy losses occurred in GS+ compared with GS, despite similar metabolizable energy intakes, and a trend for the highest plasma urea levels was found for GS+ cows (7·59 mmol/l; P<0·1). Overall, this study illustrates that the white and red clovers investigated were equivalent in energy and protein supply, also in comparison to the ryegrass. It remains open whether these forage legumes, when supplemented to a moderate-protein ryegrass, would have contributed to metabolizable protein supply or would have merely increased metabolic nitrogen load.

Is the intrinsic potassium content of forages an important factor in intake regulation of dairy cows

Hay from intensively managed grassland with high nutrient density and digestibility containing 29 g potassium/kg dry matter (DM) and hay from an alpine pasture, clearly lower in energy, digestibility and potassium (12 g/kg DM) were offered as sole feeds to 18 lactating dairy cows following a change-over arrangement within three periods of 21 days each (schedule either alpine-lowland-alpine or lowland-alpine-lowland hay). Faeces and urine were quantitatively collected over 7 days. Dry matter intake was similar and neutral detergent fibre (NDF) intake was higher with alpine than with lowland hay (1.57 kg/100 kg vs. 1.43 kg/100 kg body weight). Potassium intake was approximately three times lower with alpine than with lowland hay. Urinary water output was closely correlated with potassium intake. It was also correlated with DM intake but only in animals receiving lowland hay, while it remained independent from intake when alpine hay was fed. Plasma osmolality was lower when alpine hay was fed. As energy requirements were not covered with either diet, the lower NDF intake with lowland hay was assumed to have been caused by higher ruminal osmolality because of the higher intrinsic potassium concentrations of this hay type. Further studies are necessary to determine potassium levels critical for feed intake.

Colostrum and milk fatty acids of dairy cows as influenced by extruded linseed supplementation during the transition period.

The effects of precalving fat sources on fatty acid (FA) profile of colostrum and milk and on metabolic parameters in early lactation were determined. Two fat supplements (target: 21% fat, DM basis) fed at 1.8 kg DM d-1 were compared: Control (C; containing fractionated palm oil rich in 16:0) and Linseed (L; containing extruded linseed, rich in 18:3n-3). Sixteen dry Holstein (n = 7) and Brown Swiss (n = 9) cows were assigned to four groups receiving the supplements from 5 wk pre- to 4 wk post-calving in different sequences: CC, CL, LC and LL. Treatments did not affect metabolic parameters, milk yield or composition. Linseed supplementation increased proportions of 18:0, 18:1, 18:2 and 18:3 in colostrum and milk (except 18:1 for colostrum). The highest n-3 FA proportion was observed in milk of LL cows. For most 16 and 18 FA, a fast response occurred within the first week of lactation for cows that switched treatments over calving. Carry-over to milk of 18:3 and its biohydrogenation products from linseed fe...

Preference of dairy cows for ryegrass, white clover and red clover, and its effects on nutrient supply and milk quality

Abstract Two experiments were conducted with 30 dairy cows each, to study the preference for fresh (Experiment 1) and ensiled (Experiment 2) ryegrass, white and red clover. Both experiments consisted of three choice diets with white or red clover or both, offered with ryegrass, and two diets with ryegrass mixed with white or red clover (40% clover). Cows consumed diets with 37.7% fresh white and 45.9% red clover, and no preference was observed when the cows were offered all three forages. By contrast, cows preferred white and red clover silage (73.0 and 69.2%, respectively) over ryegrass silage (of lower nutritive quality). When offered three forages, cows preferred white (59.8%) over red clover (17.5%) and ryegrass (22.7%). Choice diets resulted in diets similar (fresh forages) or higher in nutrient content and digestibility (silages). Treatments did not affect feed intake and performance. Choices compared to mixed diets with red clover silage were preferable regarding the fatty acid composition of the milk fat. Obviously, only large differences in nutrient and energy concentration facilitate preferences for clovers over ryegrass, which could, depending on clover type, be beneficial in terms of the milks fatty acid composition.

Effect of calving period on herbage intake and nutrient turnover of Simmental and Angus suckler cows with Angus sired calves grazing subalpine and alpine pastures

Abstract Herbage intake and utilisation were measured in 12 Simmental and 12 Angus suckler cows with Angus sired calves grazing one subalpine (1000 m o.d. (ordinance datium)) and two alpine pastures (first and secondary growth; 2000 m). Calving periods were late autumn and late winter for both breeds. Herbage dry matter intake of cows and calves, determined with slow-release alkane capsules, increased from subalpine to alpine pastures from 11.9 to 15.8 and 1.1 to 3.5 kg/day, respectively. Nitrogen (N) intake was highest on regrowth pasture. Simmental cows consumed more herbage than Angus cows, even when corrected for metabolic body weight. Their calves did not differ in herbage consumption although crossbred calves had significantly higher daily gains (+16%) than Angus calves. Dam breed effects on N and phosphorous (P) excretion and N utilisation were small when corrected for differences in intake (higher in the Simmental groups). Compared to winter-calving, autumn-calving resulted in cows gaining weight but also resulted in lower daily gains of the calves despite higher herbage intake. This increased N and P losses per unit of weight gain even when calculated for cows and calves together. Accordingly, late-winter calving is advantageous for this type of alpine grazing system.

SPECIES-RICH SWARDS OF THE ALPS

The swards of the alpine grasslands represent a unique feed resource that sustains animal agriculture to the present. The complex animal–plant interactions during cattle grazing influence grassland dynamics, which under proper grazing management maintain the sustainability of these alpine swards and thereby the persistence of alpine dairy production systems. However, dairy production on alpine swards is limited by the herbage quality and the physiological impact of alpine summer grazing on dairy cattle. Abandonment of the alpine regions and shifts from milk production towards more extensive livestock systems are trends increasingly seen during recent decades. Current interest in the positive health aspects of animal products, especially in beneficial functional fatty acids in milk, may revive the interest in alpine dairy farming, because high concentrations of beneficial functional fatty acids in the lipid fraction of the milk are found in dairy products of alpine origin