Evaluation of a high forage total mixed ration on the lactational performance of late lactation dairy cows.

Dairy producers continuously ask questions challenging the paradigm of how much forage can be included in the ration to meet the nutrient requirements of lactating dairy cows to support milk production. The production and feeding of forages having both high dry matter digestibility (DMD) and neutral detergent fiber digestibility (NDFd) are needed to increase nutrient supply. Mid- to late-lactation lactating Holstein dairy cows were blocked by parity (10 primiparous and 10 multiparous), milk production (range 33.9 to 56.6; µ = 41.5 kg/d), and days in milk (DIM) (range 140 to 287; µ = 225 d) and randomly assigned within blocks to 1 of 2 rations based on medium forage (MF) or high forage (HF) inclusion rates. A forage blend consisting of 60% second cutting (2012) alfalfa haylage and 40% (2012) corn silage blended on a DM basis and then fed at either 60% (MF) or 80% (HF) of the ration DM. The alfalfa haylage DM (DMD = 75.7%) and NDF (NDFd = 55.7%) digestibility was above average, but corn silage (DMD = 72.9, NDFd = 52.3%, and starch = 32.1%) was average. The experimental design was a randomized completed block design with 4 continuous weeks for data collection preceded by a 1 wk covariate data collection period in which all cows were fed the MF ration. Cows were milked 3 times/d and milk weights recorded at each milking and milk samples were collected at each milking once weekly for analysis of milk composition. Rations were similar in crude protein (CP; 16.4%), starch (20.1%), acid detergent fiber (ADF; 21.8%), and NDF (34.1%) concentrations. Covariately adjusted milk production (28.1 and 24.1 kg/d for MF and HF, respectively) and 4% fat-corrected milk (FCM; 27.6 and 24.1 kg/d) were significantly reduced by feeding the HF ration compared with cows fed the MF ration, while milk fat (3.98 and 4.0%), milk protein (3.11 and 3.17%), milk lactose (4.81 and 4.77%), and milk solids-not-fat (8.87 and 8.77%) percentages were similar for cows fed both rations. Cows on the HF ration demonstrated a significant reduction in DMI and a trend for decreased body weight (BW) when compared with cows fed the MF ration. The forage nutrient digestibility was not adequate to support the milk production of mid- to late-lactation dairy cows when fed at 80% of the DM. The forage nutrient digestibility when fed at very high inclusion rate (80%) could not meet the nutrient requirements of mid- to late-lactation dairy cows.

Effects of Fusarium toxin contaminated wheat and of a detoxifying agent on performance of growing bulls, on nutrient digestibility in wethers and on the carry over of zearalenone.

Experiments were carried out to examine the effects of a Fusarium contaminated wheat (10 mg deoxynivalenol and 0.76 mg zearalenone, ZON, per kg dry matter) and of a detoxifying agent (Mycofix Plus, Biomin GmbH, Herzogenburg, Austria) on the growing performance of bulls, carry-over of ZON and its metabolites into body fluids and tissues, and on nutrient digestibility in wethers. The experiments were designed according to a complete two by two factorial approach which meant that both the uncontaminated control wheat and the Fusarium toxin contaminated wheat were tested both in the absence and presence of Mycofix Plus. The growing experiment with bulls (n = 14 per treatment) covered the live weight range between 244 kg and 460 kg. The respective wheat batches were included in the concentrate portion at 65%. Concentrates were fed according to plan whereas maize silage was offered for ad libitum consumption. Daily dry matter intake and live weight gain [kg per animal and day] were 7.40, 7.52, 7.51 and 7.49 and 1.367, 1.296, 1.380 and 1.307 for bulls fed the unsupplemented control wheat, the supplemented control wheat, the unsupplemented and Fusarium toxin contaminated wheat and the supplemented Fusarium toxin contaminated wheat, respectively. ZON and its metabolites were not detected in edible tissues. The most striking effects of feeding the Fusarium toxin contaminated wheat on carcass characteristics were a reduced dressing percentage, an increased weight of the emptied gastro-intestinal tract and a reduced weight of the testicles. No effect of the detoxifying agent was seen for these parameters whereas heart weight increased independently of Fusarium toxin contamination of the concentrates. Nutrient digestibility of the two wheat batches, unsupplemented or supplemented with Mycofix Plus was evaluated according to the difference method using wethers. Presence of Fusarium toxins in wheat did not influence its feeding value. The effects of the addition of the detoxifying agent were mycotoxin unspecific and resulted in an increase in apparent digestibility of crude protein and a decrease in crude fiber digestibility. It is concluded that feeding of Fusarium toxin contaminated wheat did not adversely affect performance of growing bulls (approximately 2.2 mg DON and 0.1 mg ZON per kg complete ration at a reference dry matter content of 88%) or nutrient digestibility in wethers. The effects of the detoxifying agent Mycofix Plus on growing performance and on nutrient digestibility were rather Fusarium toxin unspecific. The slightly negative effects on growing performance needs to be examined further.

Effects ofFusarium-toxincontaminated wheat in ruminant nutrition.

An experiment was carried out to examine the effects of aFusarium-contaminated wheat grain as a component of the concentrate portion (10 mg deoxynivalenol and 0.76 mg zearalenone, ZON, per kg dry matter) on performance of growing bulls, and on carry over of ZON into tissues and body fluids. In a second study, rumen physiological parameters were investigated in wethers equipped with rumen fistulae. Moreover, the influences of a detoxifying agent (Mycofix®, MP, Biomin GmbH, Herzogenburg, Austria) were considered as an additional experimental factor beside the contamination of the wheat (uncontaminated control wheat,Fusarium-toxincontaminated wheat).The fattening experiment with bulls (n=14 per treatment) covered the live weight range between 244 kg and 460 kg. Daily dry matter intake and live weight gain (kg per animal and day) were 7.40, 7.52, 7.51 and 7.49 and 1.367, 1.296, 1.380 and 1.307 for bulls fed the unsupplemented control wheat, the supplemented control wheat, the unsupplemented andFusarium toxin contaminated wheat and the supplementedFusarium toxin contaminated wheat, respectively. Concentration of ZON and its metabolites in edible tissues were lower than the detection limits of the applied HPLC-method.The results of the rumen physiological investigations revealed that the molar ratios of short chained volatile fatty acids and ammonia concentration in rumen fluid remained unchanged in response to dietary treatments whereas the addition of MP to the diets buffered the postprandial decrease in rumen pH.

The application of 13C-labelled short chain fatty acids to measure acetate and propionate production rates in the large intestines. Studies in a pig model.

The production rates of acetate and propionate were measured in the large intestine of pigs by applying the single injection technique of (1-13C)acetate and (1-13C)propionate. Both acids were injected individually through the caecal cannula and for both acids the experiments were performed during two diets with different crude fibre contents. For acetate the increase of dietary crude fibre from 5.1 to 18.3% of dry matter resulted in an increase of mean production rate from 27.4 to 56.2 mmol/h. The mean propionate production rate was raised from 3.6 to 7.0 mmol/h when the dietary crude fibre was increased from 4.4 to 24.3%. From both experimental series the contribution of hindgut fermentation to energy maintenance requirement were estimated to be in a range between 7 and 40% depending on the body weight of the animals and the percentage of dietary crude fibre.

[Energy requirement for the maintenance and utilization of energy convertible to protein and fat deposits in piglets]. / Untersuchungen zum energetischen Erhaltungsbedarf und zur Verwertung der umsetzbaren Energie für den Protein- und Fettansatz bei Ferkeln.

In respiration experiments with 16 piglets the effect of feeding level on energy metabolism was studied with the aim of estimating energy requirement and costs of protein and fat deposition. Four groups of 4 animals each were fed on different levels of digestible protein and metabolisable energy (ME). Group 1 was fed intensively, whereas the piglets of group 2, 3 and 4 received 92, 76 and 55% respectively of the amounts given to group 1. In the group 1-4 mean daily weight gain was 457, 437, 360 and 205 g respectively. As a consequence the rearing period increased from 44 days to 46, 56 and 98 days. The variation in feed intake affected not only significant differences in energy deposition but also changes in gain composition. In the groups 1-4 the average energy deposition was 4.2 MJ, 4.0 MJ, 3.0 MJ and 1.4 MJ per day and protein gain exceeded fat gain in all groups. Estimations of energy requirement for maintenance were carried out by means of multiple regression analysis using different models. As a result a value of 428 MJ ME per kg live weight 0.75 was obtained and the models used have hardly shown any influence. It seems that higher values for maintenance requirement, as formerly published, are due to different conditions of livestock management, such as temperature. For all groups the average efficiency of ME-utilisation for growth was 0.77, ranging from 0.73 to 0.82. The variation can be attributed to the changes in protein and fat formation. The groups with a higher proportion of protein in the accretion utilised metabolisable energy more efficiently than the intensively fed group 1 with the highest proportion of fat, the difference between the groups being in the range from 0.73 to 0.82. The efficiency of ME-utilisation for protein deposition was calculated to be 0.83 and for fat deposition 0.73. As a higher coefficient for fat formation may be expected in the light of the high fat content in the ration, calculations with an assumed coefficient from 0.75 and 0.80 had been carried out, showing that the efficiency of ME-utilisation for protein gain would only decrease to 0.79 and 0.73 respectively. According to these results the statement must be called in question, that the energetic efficiency of protein deposition of about 50 to 55% - as measured in numerous experiments mainly with older pigs - can generally be accepted.