Mixture Of Grass Silage Research Articles

Effects of prepartum concentrate feeding on reticular pH, plasma energy metabolites, acute phase proteins, and milk performance in grass silage–fed dairy cows

We investigated how concentrate feeding during the last 21 d of pregnancy affects reticular pH, inflammatory response, dry matter (DM) intake, and production performance of dairy cows. We hypothesized that adding concentrates to dairy cows' diet before calving reduces the decrease in reticular pH postpartum and thus alleviates inflammatory response. We also hypothesized that prepartum concentrate feeding increases DM intake postpartum and consequently improves milk performance. Two feeding experiments were conducted using a randomized complete block design. In each experiment, 16 multiparous Finnish Ayrshire cows were paired based on parity, expected calving date, body weight, and milk yield of the previous lactation. Within the pairs, cows were randomly allocated on one of the 2 dietary treatments 21 d before expected calving. In experiment 1 (Exp1), diets were ad libitum feeding of grass silage as a sole feed or supplemented with increasing amounts of concentrate offered separately (increased to 4 kg/d by d -7). In experiment 2 (Exp2), diets were ad libitum feeding of a total mixed ration containing either grass silage, barley straw, and rapeseed meal (64%, 28%, and 8% on DM basis, respectively) or grass silage, barley straw, and cereal-based concentrate mixture (49%, 29%, and 30% on DM basis, respectively). Following calving, all the cows were fed similarly and observed until d 56 postpartum. Feed intake and milk yield were recorded daily, and reticular pH was monitored continuously by reticular pH bolus. Blood samples were collected at the beginning of the experiments, 7 d before the expected calving date, 1 d (in Exp1) or 5 d (in Exp2), 10 d, and 21 d postpartum. In Exp1, concentrate feeding increased metabolizable energy intake and tended to increase DM and crude protein intake prepartum. Moreover, prepartum concentrate feeding increased the concentrations of plasma β-hydroxybutyrate and insulin, but differences in nonesterified fatty acids, glucose, or acute phase proteins were not observed. After calving, prepartum diet did not affect DM or nutrient intake, plasma energy metabolites, or milk production in Exp1. Although prepartum concentrate feeding increased reticular pH on the first day of lactation, it elevated plasma concentrations of serum amyloid-A and haptoglobin postpartum in the grass silage-based diet. In Exp2, adding concentrates to the diet based on a mixture of grass silage and straw did not affect prepartum DM intake or plasma concentrations of nonesterified fatty acids, glucose, or insulin. Adding concentrates to prepartum diet increased plasma concentration of β-hydroxybutyrate before calving as in Exp1. After calving, prepartum concentrate feeding increased DM and nutrient intake during the second week of lactation in Exp2, but no effects were observed thereafter. In contrast to our hypothesis, prepartum concentrate feeding decreased reticular pH after calving in Exp2, but no differences in inflammatory markers were observed. Based on this study, close-up concentrate feeding in diets based on grass silage with or without straw does not alleviate the decrease in reticular pH or mitigate inflammatory response postpartum.

Intake, gain and carcass traits of Hereford and Charolais bulls offered diets based on triticale, barley and grass silages

Total mixed rations (TMR) based on grass silage (GS), triticale silage (TS), mixture of GS and TS, barley silage (BS) and mixture of GS and BS were fed to fifty Hereford (HF) and fifty Charolais (CH) bulls. The proportion (g kg-1 dry matter [DM]) of the silages in the TMRs were as follows: (1) GS (600); (2) TS (600); (3) GS (300) and TS (300); (4) BS (600); (5) GS (300) and BS (300). Concentrate proportion was 400 g kg-1 DM. According to feed analyses, the GS had 15 and 8% higher metabolizable energy (ME) concentration as well as 51 and 49% higher crude protein (CP) concentration compared to TS and BS, respectively. Average DM intake (DMI) on TS and BS containing diets was higher compared to GS as a sole forage (p=0.001). Compared to the TS based rations the use of BS rations increased daily DMI by 5% (p<0.05). In CH bulls, DMI decreased 0.8 kg d-1when GS partially replaced TS or BS while in HF bulls the use of silage mixtures slightly increased DMI (0.23 kg d-1). The live weight gain (LWG) and carcass gain of the CH bulls were 5 and 26% higher, respectively, compared to the HF bulls. Inclusion of GS in the diet increased LWG and carcass gain with TS but decreased them with BS (interaction p<0.01). The experiment demonstrated lower feeding value of TS compared to BS in the diet of the bulls. Whole crop silage based rations increased DMI compared to GS as a sole forage in the TMR. When GS partially replaced TS or BS, interactions in LWG and carcass gain results demonstrated higher feeding value for BS and lower for TS compared to GS. Feeding treatments had only minor effects on carcass traits of the bulls.

A study of the structure-activity relationship of oligomeric ellagitannins on ruminal fermentation in vitro.

The aim of this study was to investigate how the degree of oligomerization of ellagitannins (ET) influences their ability to alter ruminal fermentation. Dimeric to heptameric ET were isolated from rosebay willowherb (Epilobium angustifolium) flowers and purified. Ellagitannins were tested in vitro on a mixture of grass silage and buffered rumen fluid. Total gas production was measured in real time using an automated pressure evaluation system. Methane production was monitored at regular interval by gas chromatography for 72h. The effect of ET was evaluated on 2 sources of rumen fluid using a randomized block design. Ammonia nitrogen, volatile fatty acid concentration, and pH were measured at the end of the experiment. Results show that oligomeric ET decreased gas production and total volatile fatty acid concentration proportionally to their degree of oligomerization. Methane production was also decreased by all the tested compounds and dimer was less effective than the larger ET, which showed similar levels of activity. Additionally, willowherb's oligomeric ET decreased ammonia-nitrogen and branched-chain volatile fatty acid concentrations, thus indicating reduced protein degradation by ruminal bacteria. This effect showed a quadratic relationship with the degree of oligomerization and was maximal with the tetramer. In conclusion, this study shows that the degree of oligomerization of ET has more than a simple linear effect on fermentation parameters in vitro. Large oligomers, in fact, have more detrimental effects on volatile fatty acid and gas production than small ones, while being similarly effective at inhibiting methane production.

Inclusion of sainfoin (Onobrychis viciifolia) silage in dairy cow rations affects nutrient digestibility, nitrogen utilization, energy balance, and methane emissions

Sainfoin (Onobrychis viciifolia) is a tanniniferous legume forage that has potential nutritional and health benefits preventing bloating, reducing nematode larval establishment, improving N utilization, and reducing greenhouse gas emissions. However, the use of sainfoin as a fodder crop in dairy cow rations in northwestern Europe is still relatively unknown. The objective of this study was to evaluate the effect of sainfoin silage on nutrient digestibility, animal performance, energy and N utilization, and CH4 production. Six rumen-cannulated, lactating dairy cows with a metabolic body weight (BW0.75) of 132.5±3.6kg were randomly assigned to either a control (CON) or a sainfoin (SAIN)-based diet over 2 experimental periods of 25 d each in a crossover design. The CON diet was a mixture of grass silage, corn silage, concentrate, and linseed. In the SAIN diet, 50% of grass silage dry matter (DM) of the CON diet was exchanged for sainfoin silage. The cows were adapted to 95% of ad libitum feed intake for a 21-d period before being housed in climate-controlled respiration chambers for 4 d, during which time feed intake, apparent total-tract digestibility, N and energy balance, and CH4 production was determined. Data were analyzed using a mixed model procedure. Total daily DM, organic matter, and neutral detergent fiber intake did not differ between the 2 diets. The apparent digestibility of DM, organic matter, neutral detergent fiber, and acid detergent fiber were, respectively, 5.7, 4.0, 15.7, and 14.8% lower for the SAIN diet. Methane production per kilogram of DM intake was lowest for the SAIN diet, CH4 production as a percentage of gross energy intake tended to be lower, and milk yield was greater for the SAIN diet. Nitrogen intake, N retention, and energy retained in body protein were greater for the SAIN than for the CON diet. Nitrogen retention as a percentage of N intake tended to be greater for the SAIN diet. These results suggest that inclusion of sainfoin silage in dairy cow rations reduces CH4 per kilogram of DM intake and nutrient digestibility. Moreover, sainfoin silage improves milk production and seems to redirect metabolism toward body protein accretion at the expense of body fat.

Comparison of rumen fluid inoculum vs. faecal inoculum on predicted methane production using a fully automated in vitro gas production system

The aim of the present study was to compare in vitro methane (CH4) production and other fermentation parameters from different substrates incubated either in rumen or faecal inoculum. Five different substrates were incubated in two different inocula and gas recordings were made using an automated in vitro gas production system. The substrates were: particulate matter obtained from reticulo-rumen (RR) digesta and faeces (FC) by wet sieving, timothy hay (H), first cut grass silage (S) and a mixture of grass silage and barley (50:50; SB). One gram of each substrate was incubated either in 60ml buffered rumen or faecal inoculum taken from Swedish lactating dairy cows for 48h. The results indicated that in vitro total gas production, predicted in vivo CH4 production and the ratio of CH4 production to total gas production were greater (P<0.01) for substrates incubated in rumen inoculum as compared to faecal inoculum. Mean of predicted in vivo CH4 production was greater for substrates incubated in rumen inoculum (23.5ml/g DM, 29.0ml/g OM) as compared to faecal inoculum (11.2ml/g DM, 14.3ml/g OM). Predicted CH4 production based on volatile fatty acids (VFA) stoichiometry equations (CH4VFA) showed no difference in CH4 per mol VFA (P=0.44) between the two sources of inoculum used for all substrates. Molar proportions of propionate were higher and that of butyrate were lower (P<0.01) for all substrates incubated in faecal inoculum compared to rumen inoculum. No difference (P=0.13) in molar proportions of acetate was observed. Digestibility of neutral detergent fibre (aNDFomD) and true organic matter digestibility (TOMD) were lower (P<0.01) for all substrates incubated in faecal inoculum compared to rumen inoculum. It can be concluded that using faecal inoculum tended to give lower values of predicted in vivo CH4 production as compared to rumen inoculum. The discrepancy between observed and stoichiometric CH4 production suggests an existence of acetogenesis in the hindgut.

Effect of prepartal ad libitum feeding of grass silage on transcriptional adaptations of the liver and subcutaneous adipose tissue in dairy cows during the periparturient period

Prepartal energy overfeeding may predispose cows to a state of increased insulin resistance with greater lipolysis after parturition. The aim of the study was to evaluate the effects of prepartal overfeeding in terms of abundant grass silage ration on the liver and subcutaneous adipose tissue (SAT) gene expression around parturition. Sixteen multiparous Finnish Ayrshire dairy cows were fed ad libitum either grass silage [high energy, HE; 144 MJ/d of metabolizable energy (ME) intake, n=8] or a mixture of grass silage, wheat straw, and rapeseed meal [55:40:5 (CON), 109 MJ/d of ME, n=8] during the dry period (58.2±4.89 d, mean ± standard deviation). Tissue biopsies and blood samples were collected at −14 (±4.98), 1, and 7 d relative to the actual parturition date. The HE cows had greater total dry matter intake, ME intake, and ME balance during the dry period than the CON cows. Compared with CON, the increases in body weight and body condition score were greater in HE during the dry period. Milk yield during the first 2 wk of lactation was not different between the groups. Plasma glucose, nonesterified fatty acids, insulin, glucagon, and β-hydroxybutyrate did not differ between the groups during the transition period. Dietary treatment did not affect hepatic triglyceride content; however, a delayed increase in hepatic total lipid content was observed in the HE cows at d 1 postpartum. Hepatic cytosolic phosphoenolpyruvate carboxykinase 1 mRNA expression was lower in HE than in CON at d 1 and 7 postpartum. Adiponectin receptor 1 and 2 mRNA abundance tended to be lower in SAT of HE than CON. Lower lipoprotein lipase, leptin, and stearoyl-coenzyme A desaturase mRNA abundances were observed at d 7 postpartum in SAT of the HE cows compared with the CON cows. We concluded that prepartal ad libitum feeding of grass silage may decrease insulin sensitivity and lipogenesis in SAT during peripartal period and may attenuate the increase of hepatic gluconeogenic capacity from propionate compared with a controlled-energy diet.

Effects of forage NDF content and body condition score on forage intake by Holstein–Friesian dairy cows in the dry period

This study used individual weekly results for 160 non-lactating Holstein–Friesian dairy cows in the last 5 weeks of gestation to develop regression equations based on forage NDF content and individual body condition score (BCS) for predicting dry matter (DM) intake. Results were used from treatments in which cows received the same forage and no concentrates throughout the dry period. Ten different conserved forages, either grass silages or mixtures of grass silage and barley straw, were fed in six different experiments and forage NDF ranged from 452 to 689 g/kg DM. On average cows gained 390 g live weight per day, which is less than conceptus growth at this stage – suggesting some mobilisation of maternal tissues to support conceptus growth. BCS remained unchanged at 2.5 over the dry period. DM intake declined from 10.79 kg/day 5 weeks before calving to 9.32 kg/day in the week before calving, with half of this decline occurring in the final week before calving. Intake as a percentage of live weight was moderately predicted (R2 = 0.61 for the entire period) from measures of diet composition (NDF) and cow state (BCS). There were highly significant negative effects of forage NDF and increased BCS on DM intake. The effect of BCS on DM intake was greatly reduced in the week before calving, possibly as a result of a change in metabolic priorities from gaining to losing body reserves.

Formic acid treated whole crop barley and wheat silages in dairy cow diets: effects of crop maturity, proportion in the diet, and level and type of concentrate supplementation

Three trials in dairy cows were carried out to study the effects of replacing grass silage (GS) with wholecrop silage (WCS) made of barley (BS) or wheat (WS) harvested at dough stage with a dry matter (DM) concentration of 300-450 g kg-1. All silages were ensiled using a formic acid based additive 5 l t-1. Milk production responses to energy and protein supplementation of diets were studied. In Exp. 1, BS replaced GS at the rates of 0, 200, 400 or 600 g kg-1 forage DM. Also 10 kg of concentrate containing 0 or 2 kg of rape seed meal was fed. In Exp. 2, barley was harvested at three times (BS1, BS2, BS3) at one week intervals. Barley silages were fed as a mixture with GS (40:60) and in addition BS2 and GS alone. Silages were supplemented with a cereal based farm-made concentrate (FC) or a commercial compound having a lower concentration of starch than FC. In Exp. 3, barley and wheat were harvested at two week intervals, fed as a mixture with GS (40:60) and supplemented with low or high amount of concentrate. The fermentation quality of whole crop silages was good. Weather conditions and maturity affected the proportion of ear in the crop and subsequently the ratio of non-structural carbohydrates to NDF in the silage. The inclusion of WCS depressed diet OM digestibility depending on the digestibility of GS and the proportion of WCS in the diet. However, mixing GS and WCS did not depress intake. Subsequently the use of mixtures maintained or even increased milk yield as compared with GS diet in Exp. 2 and 3. In Exp. 1, higher proportions (400, 600 g kg-1) of BS decreased milk yield. Minor effects of growth stage on milk production were observed with barley whereas delaying wheat harvest increased milk yield. Different types and levels of concentrate induced mainly similar intake and milk yield responses with diets based on GS alone or on mixtures of GS and WCS. The synergistic effect of mixing GS and WCS was more positive in experiments where the protein concentration of concentrate was high (200 g kg-1 DM).;

Comparative Evaluation of Alternative Forages to Grass Silage in the Diet of Early Lactation Dairy Cows

Fifty-six autumn-calving Holstein-Friesian cows, blocked on the basis of days in milk (27.6±10.65 d), lactation number (3.1±2.21), and preexperimental milk yield (28.4±6.69kg) were used to examine the effects of replacing 330 g/kg of dry matter (DM) of first-cut perennial ryegrass silage with either fermented whole-crop wheat (WCW), urea-treated processed WCW, or corn silage on subsequent feed intake, milk production, and efficiency of nitrogen utilization. The DM (g/kg), crude protein (CP, g/kg of DM) and in vitro DM digestibility (g/kg) of the forages were 204, 179, and 762 for grass silage; 389, 90, and 711 for fermented WCW; 795, 141, and 768 for urea-treated processed WCW; and 346, 93, and 783 for corn silage, respectively. Four forage treatments were evaluated as follows: 1) grass silage as the sole forage (GS); 2) a mixture of grass silage and fermented WCW silage, (F-WCW); 3) a mixture of grass silage and urea-treated processed WCW, (UP-WCW); and 4) a mixture of grass silage and corn silage (CS). In all cases, the alternative forages comprised 67% of the forage mix on a DM basis. Isonitrogenous diets were formulated by offering all cows 8kg of concentrate as fed, formulated to different CP concentrations. Cows were offered these diets from 28 to 104 d in milk. Total DM intake and milk yield were greater on UP-WCW (20.0 and 30.2kg/d) and CS (18.3 and 33.2kg/d) than on GS (13.5 and 26.5kg/d). Although DM intake was greater on F-WCW (17.1kg/d) than on GS, milk yield was not significantly greater (+2.7kg/d). Milk protein concentration was greater on F-WCW (30.5 g/kg), UP-WCW (31.3 g/kg), and CS (30.7 g/kg) than on GS (28.5 g/kg). However, there was no difference between treatments in milk fat or lactose concentrations. Body weight change was greater for cows offered GS (−0.27kg/d) than for those offered UP-WCW (−0.01kg/d) and CS (+0.05kg/d) but not compared with those offered F-WCW (−0.06kg/d). There was no effect of treatment on plasma glucose, nonesterified fatty acids, β-hydroxybutyrate, urea, or total protein at d 64±17.4 and d 92±17.4 postpartum. Efficiency of N utilization was greatest for CS with 0.36 of N intake being recovered in milk compared with 0.28, 0.32, and 0.26 for GS, F-WCW, and UP-WCW, respectively. There was no effect of treatment on milk urea N concentration or the urinary allantoin N to creatinine N ratio. The results of this experiment indicate that corn silage is a more suitable supplementary forage to grass silage than fermented or urea-treated processed WCW, with advantages realized in milk production and more efficient N utilization.

Effects of contrasting forage diets on phosphorus utilisation in lactating dairy cows

The effects of different forage mixtures on duodenal flow and faecal output of phosphorus (P) were measured in lactating dairy cows in two experiments. The forages comprised grass silage (GS) alone or mixtures of GS and urea-treated whole crop wheat (WCW). Replacement of GS by high levels of WCW resulted in a significant decrease in total P (TP), water-soluble P (WSP) and acid-soluble P (ASP) intakes, but increased phytate P (PP) and acid-insoluble P (AIP) intakes. Duodenal flows of all P fractions were unaffected by dietary treatments. However, the amounts of all fractions flowing to the intestine were much higher than the amounts consumed—with the exception of AIP, which was unchanged, and PP, which was considerably reduced. Diets did not significantly affect faecal outputs of TP, ASP, PP and AIP; however, faecal outputs of WSP were significantly higher on WCW than GS diets. Inclusion of WCW significantly decreased TP and WSP availabilities in the total tract but did not affect PP and AIP availabilities. A new fraction of P, which was not present in the feeds, was found in significant amounts in the intestines and proved to be soluble in dilute acid but insoluble in water. Estimated annual excretions for a herd of 100 cows ranged from 1550 to 1721 kg for total P of which 337–786 kg was WSP. The results suggest that GS based diets deposit more P in the environment. However, the potential to cause P pollution depends not only on the quantity but also on the nature of faecal P and on soil parameters.

Effects of supplementary concentrates on growth and partitioning of nutrients between different body components in steers fed on grass silage at similar levels of metabolizable energy intake

A comparative slaughter experiment was carried out to examine the effects of feeding either grass silage alone or a mixed diet of silage and concentrate on animal performance and the partitioning of nutrients between lean and fat deposition in steers. Eighteen Hereford×Friesian steers were randomly assigned to two dietary treatments; grass silage only (S) or a mixture of grass silage and a barley/soya bean meal concentrate (80[ratio ]20 on fresh basis) in the ratio of 60[ratio ]40 (on a metabolizable energy basis; SC), and to one of three target slaughter liveweights, 250, 350 or 500 kg. Metabolizable energy (ME) intake was maintained at 800 kJ ME per kg metabolic liveweight (kg0·75) per day. The relationships between chemical composition and empty body weight (EBW) at slaughter were assessed using allometric equations (logey=logea+blogeEBW). When assessed across the slaughter weights, supplementing silage with concentrates resulted in higher rates of liveweight (P&lt;0·001), carcass fat (P&lt;0·05) and protein (P&lt;0·01) gains and a reduction in time taken to reach the average slaughter weight by 57 days (P&lt;0·001). Carcass protein deposition was relatively linear across the slaughter weights (250–500 kg) and the relationship with EBW was Y=0·2372X0·8831 across treatments and did not differ between the diets. The rate at which carcass fat was deposited in relation to weight across all steers was Y=0·0004X1·9648 and was not different between the two diets. Hence, ratios of carcass fat[ratio ]protein and carcass fat[ratio ]protein gain ratios were not different. The results suggest that the main effect of feeding grass silage compared with grass silage-concentrate at similar levels of ME intake was to increase the rate of tissue accretion, but nutrient partitioning between fat and protein deposition was unchanged. There was no evidence of increased carcass fat[ratio ]protein deposition in silage-fed animals, which suggests that there is no problem of greater fat and reduced protein deposition in animals fed higher quality grass silage.

Attempts to improve the utilization of urea-treated whole-crop wheat by lactating dairy cows

AbstractThis paper reports the results of three experiments designed to attempt to improve the efficiency of milk production from diets based on a 1: 2 dry matter (DM) mixture of grass silage and whole-crop wheat (WCW) harvested at 550 to 600 g DM per kg and treated with 40 g urea per kg DM. In the first experiment a control diet of the forage mixture offered ad libitum with 9 kg fresh weight (FW) per day of a concentrate mix was compared with seven treatments in which the forage or the concentrates were varied. Eight multiparous cows were used in a four-period incomplete change-over design with 4-week periods. Caustic treatment of the WCW increased DM intake (P &lt; 0·001) but tendencies for higher yields of milk and milk protein were not significant. Replacement of 2 kg FW concentrates per day by the same weight of molasses as a 24-h pre-soak of the forage (molasses pre-treatment) or added to the forage at feeding increased DM intake (P &lt; 0·001) but did not increase milk yield or yield of milk solids. Molasses pre-treatment and molasses added to the concentrates reduced milk protein concentration (P &lt; 0·05). Replacement of 2 kg FW concentrates per day by the same weight of ground wheat increased DM intake when added to the concentrates (P &lt; 0·001) but not when added to the forage and milk yield was unaffected by either method of addition. The ground wheat tended to reult in higher milk protein concentrations than the molasses. Increasing the digestible undegradable protein content of the concentrates had no significant effect on food intake or milk production. In the second experiment diet digestibility and energy and nitrogen (N) balance were measured for the control diet and three of the treatments from experiment 1 in four multiparous cows in a 4 ✕ 4 Latin-square experiment with 5-week periods. There were no significant effects on food intake or milk yield. Caustic treatment reduced starch digestibility (P &lt; 0·001) and increased neutral-detergent fibre (NDF) digestibility (P &lt; 0·05) but had no effects on energy utilization. It also reduced N intake (P &lt; 0·01) and urine N losses (P &lt; 0·001) by reducing the ammonia concentration of the WCW. Molasses added to the forage or concentrates reduced milk protein concentration (P &lt; 0·05) and digestibility of both starch and NDF (P &lt; 0·05) but energy utilization was unaffected. In a further Latin-square experiment with the same treatments and four fistulated lactating cows, caustic treatment reduced daily mean ammonia concentration (P &lt; 0·01) and increased daily mean pH (P &lt; 0·01) in the rumen. It is concluded that these treatments did not generally improve the value of WCW although caustic treatment increased milk yield and milk protein yield consistently but not significantly. However practical problems may limit its use on the farm. Urea-treated WCW must be accepted as being a relatively low-energy food although with high intake characteristics, and future work should concentrate on evaluating WCW harvested at an earlier stage of maturity.

Measuring diet selection in dairy cows: effect of training on choice of dietary protein level

AbstractIn a 7-week experiment, the ability of lactating Holstein-Friesian cows to select a consistent diet from two similar foods differing in calculated metabolizable protein to energy (MP/ME) yield was investigated. The effect on diet selection of training through previous access to foods separately, was measured. Food intake was recorded with 28 computer-linked feeders. All foods were mixtures of grass silage and concentrates. In week 1, all feeders contained a standard food. In weeks 2 to 7 a low protein food (LP) and a high protein food (HP) were offered in 14 feeders each. Group CHOICE had access to both foods as a choice from week 2. Group TR1 was trained by access to one food during days 8 to 10 and to the other during days 11 to 13. Group TR2 received the same training as group TR1 during days 8 to 13 which was repeated once during days 14 to 19. After training, TR groups had access to both foods as a choice. Groups LOPRO and HIPRO had only access to LP or HP, respectively in weeks 2 to 5 and to both foods as a choice in weeks 6 and 7. In weeks 2 to 5 LOPRO COWS consumed less dry matter and produced less milk than CHOICE or HIPRO cows. After a week of adaptation, untrained CHOICE COWS selected 662 (s.e. 27) g HP per kg of intake, a choice that differed significantly (P &lt; 0·01) from random. In weeks 4 to 7 TR cows established similar diet choice: 696 (s.e. 21) g HP per kg intake and the proportion selected was unaffected by length of training. The between-day variation in diet choice within cows was not affected by treatment. It is concluded that, under the circumstances tested, training was not required for cows to distinguish between two mixed foods with different calculated MP/ME ratios and to select proportions significantly different from random.

Digestibility of diets of grass silage and whole crop wheat in the rumen of lactating cows

Forage mixtures containing urea-treated whole crop wheat (WCW) have been shown to be used less efficiently than expected by dairy cows due to low digestibility, particularly of the starch. The purpose of the present experiment was to measure the contribution of the rumen to the digestibility of diets based on grass silage or mixtures of grass silage and urea-treated WCW.

Digestibility of diets of grass silage and whole crop wheat in the rumen of lactating cows

Forage mixtures containing urea-treated whole crop wheat (WCW) have been shown to be used less efficiently than expected by dairy cows due to low digestibility, particularly of the starch. The purpose of the present experiment was to measure the contribution of the rumen to the digestibility of diets based on grass silage or mixtures of grass silage and urea-treated WCW.

The effect of concentrate level on feed intake and milk production of dairy cows offered mixed forage diets

The increasing interest in the potential of forage mixtures for milk production in the UK resulted in a three year study being commissioned at the Centre for Dairy Research by the Milk Marketing Board. Year 1 compared the effect on forage intake and yield of milk and milk constituents of replacing grass silage (GS) with either fodder beet (FB), urea-treated (4%) (UW) or fermented whole-crop wheat (FW) or brewers grains (BG) at 330 g/kg of forage DM or maize silage at either 330 (MS) or 750 (MSH) g/kg forage DM. All cows received 6 kg DM/day of an appropriate concentrate so that dietary crude protein (CP) was equalised. Tire use of forage mixtures significantly increased DM intake and milk yield. Significant changes were also recorded in milk quality. Milk fat content was depressed by BG and MSH but increased by FB, while MS and FB increased milk protein content when compared with GS. The aim of the current study was to determine the effect of concentrate level on feed intake and milk production of Friesian cows offered a forage ration of either GS or mixtures of GS and either 330 g/kg forage DM of MS, FB or BG, or 750 g/kg forage DM of maize silage (MSH).

The effect of concentrate level on feed intake and milk production of dairy cows offered mixed forage diets

The increasing interest in the potential of forage mixtures for milk production in the UK resulted in a three year study being commissioned at the Centre for Dairy Research by the Milk Marketing Board. Year 1 compared the effect on forage intake and yield of milk and milk constituents of replacing grass silage (GS) with either fodder beet (FB), urea-treated (4%) (UW) or fermented whole-crop wheat (FW) or brewers grains (BG) at 330 g/kg of forage DM or maize silage at either 330 (MS) or 750 (MSH) g/kg forage DM. All cows received 6 kg DM/day of an appropriate concentrate so that dietary crude protein (CP) was equalised. Tire use of forage mixtures significantly increased DM intake and milk yield. Significant changes were also recorded in milk quality. Milk fat content was depressed by BG and MSH but increased by FB, while MS and FB increased milk protein content when compared with GS. The aim of the current study was to determine the effect of concentrate level on feed intake and milk production of Friesian cows offered a forage ration of either GS or mixtures of GS and either 330 g/kg forage DM of MS, FB or BG, or 750 g/kg forage DM of maize silage (MSH).

Diet selection in dairy cows: effect of training on choice of dietary protein level

An experiment was carried out to determine the ability of lactating cows to select a diet from two similar feeds differing in the ratio of metabolisable protein to energy (MP/ME) content and to investigate the effect of training through previous access to feeds separately on diet choice.Holstein-Friesian cows (n=36), 1-5 months in lactation, yielding 37 (s.d.=5) kg of milk were housed in a cubicle shed equipped with 28 computer linked Hokofarm feeders which can be programmed to give or deny specific animals access and record intake, meal size and meal duration. All feeds were mixtures of grass silage and pelleted concentrates. Approximately 75 % of daily offer was given in the morning and topping up occurred during afternoon milking. After adapting to feeders and feed for at least two weeks, intake was recorded in week 1 when all feeders contained a standard mixed feed calculated to contain 8.3 g MP/MJ ME. In weeks 2-7 a low protein (lp) and a high protein (hp) feed were offered in 14 feeders each (in the order 7 lp, 7 hp, 7 lp, 7 hp).

Diet selection in dairy cows: effect of training on choice of dietary protein level

An experiment was carried out to determine the ability of lactating cows to select a diet from two similar feeds differing in the ratio of metabolisable protein to energy (MP/ME) content and to investigate the effect of training through previous access to feeds separately on diet choice.Holstein-Friesian cows (n=36), 1-5 months in lactation, yielding 37 (s.d.=5) kg of milk were housed in a cubicle shed equipped with 28 computer linked Hokofarm feeders which can be programmed to give or deny specific animals access and record intake, meal size and meal duration. All feeds were mixtures of grass silage and pelleted concentrates. Approximately 75 % of daily offer was given in the morning and topping up occurred during afternoon milking. After adapting to feeders and feed for at least two weeks, intake was recorded in week 1 when all feeders contained a standard mixed feed calculated to contain 8.3 g MP/MJ ME. In weeks 2-7 a low protein (lp) and a high protein (hp) feed were offered in 14 feeders each (in the order 7 lp, 7 hp, 7 lp, 7 hp).

Dairy rations based on mixtures of grass silage and maize silage: responses to supplemental rumen fermentable starch and rumen degradable protein

Compared with most grass silages, maize silage has a low ratio of rumen degradable protein: fermentable energy. Unlike grass silage, maize silage contains rumen fermentable starch. These differences imply that a different regimen of supplemental nutrients is required to optimise cow performance on rations containing maize silage compared with rations based on grass silage. The objective of this study was to define responses of dairy cows fed rations based on maize silage to supplements of rumen fermentable starch (RFS) and effective rumen degradable protein (ERDP).