Hannele Khalili

Prediction of the relative intake potential of grass silage by dairy cows

Data based on the mean treatment values from production studies in lactating dairy cows were used to estimate relationships between silage composition and silage dry matter intake (SDMI). Data from 21 studies were used to estimate relationships between D-value (g digestible organic matter in kg dry matter (DM)) and crude protein (CP) content, and SDMI. The silages were harvested at different maturities but using the same ensiling techniques within the study. Relationships between silage fermentation characteristics and SDMI were estimated using data from 47 studies. The silages were harvested at the same time from the same sward but using various additives. When factorial designs were used, silage data within each treatment (subexperiment) were recorded separately. The data sets included 125 D-value and 234 fermentation observations. Relationships between SDMI and silage parameters were analyzed using mixed model regression analyses with experiment as a fixed factor and subexperiment within experiment as a random factor. The ranges for silage CP concentration and D-value were 111 to 238 (S.D. 25.2) and 589 to 756 (S.D. 48.5) g/kg DM, respectively. D-value was a much better predictor of SDMI than CP (R2 within experiment 0.71 vs. 0.26). The effect of D-value on SDMI diminished with increasing level of concentrate supplementation (interaction P<0.001). D-value had a greater effect on SDMI when the total DM intake was high. SDMI was negatively correlated with concentrations of ammonia N, lactic acid, individual and total volatile fatty acids and total fermentation acids and positively correlated to the concentration of residual water soluble carbohydrates. Total acid concentration was the best SDMI predictor of individual fermentation parameters (R2 within experiment 0.41) followed by lactic acid and ammonia N. Use of quadratic regressions generally increased the variation accounted for by the model. The best multiple regression accounted for 0.51 of the variation in SDMI within experiment. To facilitate interpretation of data, a theoretical model is presented. An interplay between physical load and capacity to use energy determines SDMI of well-fermented silages over the whole range of D-values. With increasing extent of fermentation SDMI is constrained by nutrient imbalance, most probably amino acid to energy ratio at the tissue level, resulting from reduced microbial protein synthesis in the rumen. Low palatability can further constrain silage DM intake. For advisory silage evaluation the following model predicting relative SDMI is proposed: SDMI index=100+0.151×(D-value−690)−0.000531×(TA2−6400)−4.7650 [Ln(Ammonia N) −Ln(50)], where D-value and total acids (TA) are expressed as g/kg DM and ammonia N as g/kg total N, respectively. Regression coefficients are scaled to a mean SDMI of 10 kg DM/day. The values of 690, 80 and 50 are used as standard D-value (g/kg DM), total acid (g/kg DM) and ammonia N (g/kg N) for high quality restrictively fermented silages. The model parameters were limited to those which are currently available for Finnish farm silage analyses, i.e., by near infra-red reflectance spectra (D-value) and electrometric titration (fermentation parameters).

Sucrose supplements in cattle given grass silage-based diet. 2. Digestion of cell wall carbohydrates

The effect of sucrose supplements on cell wall digestion was studied in a 4 × 4 Latin square experiment using male cattle fitted with a rumen cannula and a simple T-piece duodenal cannula. The control diet (C), fed at the level of 5.3 kg dry matter (DM) day−1, consisted of grass silage (700 g kg−1 DM), barley (240 g kg−1 DM) and rapeseed meal (60 kg−1 DM). The three other diets were supplemented with 1.0 kg of sucrose given twice daily (S), or twice daily with 0.25 kg day−1 of sodium bicarbonate (B), or as a continuous intraruminal infusion (I). Duodenal flows of neutral detergent fibre (NDF), acid detergent fibre (ADF), cellulose and hemicellulose were estimated using chromium (Cr)-mordanted straw and CoEDTA as flow markers. The degradation characteristics of silage DM, NDF and ADF were determined by incubating the samples in nylon bags in the rumen for different periods of time. Sucrose supplements increased duodenal flows of NDF (P < 0.1), ADF (P < 0.05), cellulose (P < 0.05) and hemicellulose (P < 0.1) compared with Diet C. In spite of partial compensation for the reduced rumen digestion in the hindgut, the total digestibility of cell wall carbohydrates decreased when sucrose was included in the diet. Among the sucrose diets, bicarbonate supplement alleviated the adverse effect of sucrose on fibre digestion and the values observed with Diet B were similar to those with Diet C. Continuous infusion of sucrose had a similar adverse effect on fibre digestion to Diet S. Feeding Diets S and I decreased the disappearance of silage DM, NDF and ADF from nylon bags, especially after incubation periods of 12–48 h, and as a result the rate constants for the degradation of different silage components were lower (P < 0.05) than with Diets C and B. Sucrose supplements increased the lag time of fibre digestion.

Sucrose supplements in cattle given grass silage-based diet. 1. Digestion of organic matter and nitrogen

In a 4 × 4 Latin square experiment, four Friesian male cattle fitted with rumen and duodenal cannulas were given a basal diet of grass silage, barley and rapeseed meal (700, 240 and 60 g kg−1 total dry matter (DM)) at the rate of 5.3 kg DM day−1 (Diet C) or supplemented with 1.0 kg day−1 of sucrose given either twice daily (Diet S), twice daily with 0.25 kg day−1 of sodium bicarbonate (Diet B) or as a continuous intraruminal infusion (Diet I). Duodenal flow was estimated using chromium (Cr)-mordanted straw and cobalt ethylenediamine tetracetic acid as digesta flow markers, and purine bases of nucleic acids as microbial markers. Samples of rumen fluid were taken for estimation of rumen pH and the concentrations of ammonia nitrogen (N), volatile fatty acids and lactic acid. Sucrose supplements increased the amount of organic matter (OM) entering the duodenum (P < 0.05) and voided in faeces (P < 0.001). The proportion of digestible OM apparently digested in the rumen averaged 0.68 and was not significantly affected by the diet. Sucrose supplements decreased rumen pH (P < 0.05), ammonia N concentration (P < 0.001) and molar proportions of acetate (P < 0.001) and isovalerate (P < 0.01), and increased those of butyrate (P < 0.01) and valerate (P < 0.05). Among the sucrose diets, the concentration of lactic acid and molar proportion of butyrate were highest with Diet S. Sucrose supplements increased the rumen liquid dilution rate (P < 0.01) and liquid outflow (P < 0.001) from the rumen. Feeding sucrose diets increased (P < 0.05) the quantities of non-ammonia N and microbial N entering the small intestine, and the amount of N subsequently excreted in faeces. The efficiency of microbial N synthesis (g N kg−1 OM apparently digested in the rumen) was non-significantly increased by sugar supplements. Among the sucrose diets, continuous infusion of sucrose tended to decrease ammonia N concentration and stimulate microbial N synthesis more than feeding sucrose twice daily.

Relationships between silage fermentation characteristics and milk production parameters: analyses of literature data

Abstract Data from published production studies in lactating dairy cows were used to estimate relationships between silage fermentation characteristics and milk production parameters. The study used data from 47 experiments including 234 observations (treatment means). Within each experiment the silages were harvested at the same time from the same sward but using various additives. When factorial designs were used, silage data within each treatment (subexperiment) were recorded separately. Relationships between production parameters and silage fermentation parameters were analysed using mixed model regression analyses; with subexperiment within experiment as a random factor. Yields of milk, energy corrected milk (ECM), milk fat and protein decreased with increasing extent of in-silo fermentation. The effects were more profound for ECM than milk yield, because both milk fat and protein concentrations decreased ( P R 2 value between ME intake and ECM yield was 0.74 indicating that the effects on ECM yield were mainly derived from increased silage intake.

Sucrose supplements in cattle given grass silage-based diet. 3. Rumen pool size and digestion kinetics

Abstract The effects of sucrose supplements on rumen pool sizes and digestion kinetics were studied in a 4 × 4 Latin square experiment in male cattle fitted with rumen and duodenal cannulas. The basal diet (Diet C), fed at the level of 5.3 kg dry matter (DM) day −1 , was comprised of grass silage, barley and rapeseed meal (700, 240 and 60 g kg −1 DM, respectively). The other three diets were supplemented with 1.0 kg day −1 of sucrose administered twice daily (Diet S), or twice daily with 0.25 kg day −1 of sodium bicarbonate (Diet B), or as a continuous intraruminal infusion (Diet I). Pool sizes of rumen digesta and its components, and the digestion kinetics of cell wall carbohydrates, were derived from rumen evacuation. The potential digestibility of rumen digesta and faeces was determined by incubating the samples for 240 h in nylon bags in the rumen. The main effect of sucrose supplements was to increase the rumen pool size of DM and fibre constituents. The greater rumen pool size of neutral detergent fibre (NDF) and acid detergent fibre (ADF) with sucrose diets consisted mainly of digestible NDF and ADF. Inclusion of sodium bicarbonate in the diet almost completely alleviated the effect of sucrose on rumen pool sizes. There were close negative correlations ( r 2 0.96–0.999) between the rumen pool size of cell wall components and in vivo digestibility of the corresponding component. The rates of digestion ( k d ) were decreased by sucrose supplements. The values for k d of NDF were 0.0594, 0.0444, 0.0557 and 0.0448 for Diets C, S, B and I, respectively. The rate of passage ( k p ) or its reciprocal, rumen residence time (RRT), were not significantly affected by the diet. Longer RRT was measured for digestible NDF (71.5 h) than for total NDF (61.7 h) and for indigestible NDF (49.7 h). The potential digestibility of DM, NDF and ADF of rumen ingesta and faeces was higher with Diets S and I than with Diets C and B. Faecal output of digestible NDF was greater with Diets S and I than with Diets C and B.

Effect of replacement of concentrate mix by wilted sesbania (Sesbania sesban) forage on diet digestibility, rumen fermentation and milk production in Friesian X Zebu (Boran) crossbred cows fed low quality native hay

Sesbania (Sesbania sesban) forage, including leaves and edible stems (stem diameter 2–3 mm) in the ratio 1:3, as a replacement for concentrate supplement in dairy cattle feeding was studied in a 4 × 4 Latin square design experiment with four rumen-cannulated lactating crossbred cows. All the animals were fed a basal diet of low quality native hay, mineral lick and water ad libitum. In Diet 0, the basal diet was supplemented with 4.5 kg air dry commercial concentrate based on noug (Guizotia abyssinica) cake and wheat middling. In Diets 33, 66 and 100, respectively, one-third, two-thirds and all of the concentrate was replaced with sesbania forage. Nitrogen content of sesbania forage was clearly lower than that of concentrate, but rumen degradation constants indicated that for both the concentrate and the wilted sesbania forage, a major part of the nitrogen was instantly degraded. Increasing sesbania forage on offer in the diet caused a slight, but statistically significant (P < 0.01) linear decline in total feed intake, because all sesbania was not consumed. The simultaneous very clear linear decrease in daily milk yield was also statistically significant (P < 0.01). Dietary crude protein digestibility decreased (P < 0.05) with increasing sesbania supplementation, because the proportion of easily or potentially degradable protein was smaller in sesbania than in the concentrate. The supply of metabolisable energy, calculated based on digestible organic matter, was always sufficient to maintain the highest milk production level of Diet 0, but insufficient digestible crude protein limited the milk yield on sesbania diets. To assess nutritionally harmful effects of sesbania forage, long-term trials with more animals are needed.

Wilted tagasaste (Chamaecytisus palmensis) forage as a replacement for a concentrate supplement for lactating crossbred Friesian × Zebu (Boran) dairy cows fed low-quality native hay

An experiment was conducted with four rumen-cannulated crossbred cows in a balanced 4 × 4 Latin square to study the effect of wilted tagasaste (Chamaecytisus palmensis) forage on rumen parameters and milk yield. The cows were fed a basal diet consisting of ad libitum native hay, mineral lick and water. Tagasaste forage was used to replace, on a dry matter (DM) weight-for-weight basis, 0, 33, 66 and 100% of 4.5 kg of an air-dry concentrate mix based on noug (Guizotia abyssinica) cake and wheat middlings that was used to supplement the basal diet. The rumen degradation of nitrogen tagasaste forage was intermediate between that of hay and wilted sesbania (Sesbania sesban) forage. Contents of tannic compounds were low—lower in tagasaste than in sesbania forage. The cows were healthy throughout the 84 day experiment. However, they refused to eat all the tagasaste forage at the higher levels of replacement (66 and 100%), resulting in significantly (P < 0.001) lower total DM and crude protein intakes. It was concluded that poor palatability might be the main reason for low intake of tagasaste. Decline in nutrient intakes resulted in a simultaneous linear decrease (P < 0.01 − 0.05) in milk yield and milk protein content. Replacing concentrate with tagasaste did not have a significant effect on the apparent total tract digestion of dietary DM of organic matter, but it decreased the crude protein digestion (P < 0.05) and increased (P < 0.01) cell wall digestion linearly. It also had clear and statistically significant (P < 0.01 − 0.05) linear effects on rumen fluid parameters. pH and acetic acid increased, while propionic and butyric acids and ammonia decreased, in the rumen fluid. Metabolizable energy supply, calculated from the intake of digestible organic matter, was sufficient on all the diets to maintain the milk production level recorded with 0 or 33% replacement (average 5.2 kg day−1), but the supply of crude protein was insufficient to support this production level when 56 or 100% of the concentrate was replaced by tagasaste. It was concluded that tagasaste forage could not be used to replace concentrate as a supplementary feed for crossbred dairy cows without decreasing feed intake and milk yield. It was, however, also concluded that tagasaste should be evaluated in an environment where practical alternatives for energy or protein supplements are scarce or non-existent.

Need for protein supplementation in the diet of growing dairy bulls fed total mixed ration based on moderate digestible grass silage and barley

-1 ; p < 0.01) and energy intake (C 112.4 vs. BPWDS 120.3 MJ d -1 ; p < 0.05). The apparent organic matter digestibility (OMD) was 5% higher in the BPWDS diet than in the C diet (p < 0.001), but the RSM and WDS diets did not differ from the C diet in OMD. The results indicate that the supply of protein in dairy bulls is most probably adequate with moderate digestible, well-preserved grass silage and barley-based concentrates when intake of digestible organic matter is high enough to support microbial protein synthesis in the rumen.

Effects of increasing concentrate energy supply on the performance of loose-housed dairy cows fed grass silage-based diets

Abstract The effects of increased concentrate level on milk production was assessed during two consecutive indoor feeding seasons according to a continuous randomised block design using 44 (season 1) and 47 (season 2) Finnish Ayrshire cows. Treatments allocated according to a 2×2 factorial design consisted of two concentrate levels and two protein feeding systems. Low and high concentrate feeding regimens were applied to multiparous cows as 9 and 14 kg/day during days 1–150 of lactation and 8 and 11.5 kg for days 151–224, respectively. Primiparous cows received proportionately 0.80 of that fed to multiparous cows. In order to identify the effects of concentrate energy alone, concentrates were formulated so that increases in concentrate feeding resulted in either a constant supply of concentrate crude protein (CP) (mean 1.4 kg/day) or constant intake of rapeseed meal (RSM) (mean 1.7 kg DM/day). Consequently, concentrate CP content decreased with the increasing level of concentrate. Concentrate was offered through computerised self-feeders and silage was fed ad libitum. Increasing energy intake at a constant CP level seemed to have a more negative effect on silage dry matter (DM) intake compared with feeding a constant supply of RSM. Increases in concentrate DM intake resulted in mean substitution rates of 0.48 and 0.25 for CP and RSM diets, respectively. However, the positive effect of concentrate supplementation on milk yield was independent of protein feeding strategies. Milk production increased ( P

Effects of replacing different proportions of barley grain by barley fibre on performance of dairy bulls

The objective of the present experiment was to study the effects of partial replacement of barley grain with barley fibre (BF) on animal performance, carcass traits and diet digestibility of growing dairy bulls. The feeding experiment comprised 20 Finnish Ayrshire bulls and 12 Holstein-Friesian bulls, and four treatments (8 bulls per treatment). There were four diets with two offered at stage 1 (from the initiation of the study to 450 kg live weight) and four at stage 2 (from 450 kg live weight to slaughter). The control diet (BF0) included grass silage (460 g kg –1 dry matter) and barley grain (540), BF25 diet included grass silage (460), barley grain (405) and BF (135), BF50 diet included grass silage (460), barley grain (270) and BF (270), and BF75 diet included grass silage (460), barley grain (135) and BF (405). At stage 1 there were only two treatments (BF0 and BF50) and at stage 2, all four treatments were included. All bulls were fed total mixed ration ad libitum. The mean initial live weight of the bulls was 261 kg and the mean final live weight 650 kg. At stage 1 there were no significant treatment differences in dry matter, energy or protein intakes or in live weight gain. At stage 2, replacing barley grain with BF led to a linear decrease of daily live weight gain (P < 0.05) and a linearly reduced feed conversion (kg dry matter kg –1 live weight gain) (P < 0.05). The apparent digestibility of the organic matter and neutral detergent fibre decreased linearly with increasing BF supplementation (P < 0.001). The dressing proportion and the carcass fat score decreased linearly (P < 0.05) with partial replacement of barley grain with BF. On carcass conformation, treatment had a significant (P < 0.05) quadratic effect: the BF25 and BF50 diets were classified highest. The results indicate that 50% of barley starch can be replaced with BF without affecting growth, but feed efficiency factors may decrease when barley starch is replaced with BF. At 75% replacement, feed intake was reduced, which resulted in a lower energy intake and reduced level of performance.