This research paper addresses the hypotheses (1) that milk produced from hay-fed cows differs from that of silage-fed cows and (2) that silage type has an important impact, too. Four diets differing in forage type but with equal estimated milk production potential and a forage:concentrate ratio of 0.85 : 0.15 were compared regarding their effect on feed intake, milk yield and milk properties. The forages tested were hay, grass silage, conventional short-chopped and long-chopped maize silage subjected to a novel processing technology (Shredlage®). Twenty-four dairy cows were fed two of the four diets in two consecutive runs in an incomplete (4 × 2) Latin-square design (n = 12 per diet). Each experimental period lasted 22 d, with 12 d of adaptation and 10 d of sampling. During sampling, feed intake and milk yield were recorded daily, milk composition and coagulation properties were determined four times. The composition of the diet ingredients was analysed weekly. Data were analysed with a mixed model considering feed, period and their interaction as fixed effects. Stage of lactation, milk yield and milk composition from the pre-experimental period were used as covariates in the model. Dry matter intake was lower with the long-chopped processed maize silage compared to the other three groups. There were some diet differences in intakes of net energy for lactation and absorbable protein in the duodenum, but this did not result in changes in milk yield. The milk fat content was higher with the grassland-based diets compared to the maize silage diets. No treatment effect on milk acidity and rennet coagulation properties was observed. In conclusion, there were no indications for specific physico-chemical properties of milk from a hay-based diet, and maize processing technology was not of large effect either. Future investigations should focus on sensory differentiation of the milk produced with different forages.

The objective of the current study was to evaluate the effects of sugarcane and maize silage mixture v. maize silage in diets of Holstein cows and investigate performance under two environmental conditions. The cows were placed in freestalls, with individuals and stalls assigned to one of four treatments according to a replicated 4 × 4 Latin square design with 20-day periods divided into 11 days of adaptation (wash-out period) and 9 days of collection. Treatments were arranged in a 2 × 2 × 2 factorial design: total diets (maize silage (MS-based diet), the roughage mixture (RM-based diet, sugarcane : maize silage, 500 : 500 g/kg DM) plus concentrate); environmental conditions (with (W) and without (Wo) fan and nebulizers); and measurement times (09.40 and 14.00 h). The temperature and relative humidity was higher at 14.00 h and contributed to increased temperature-humidity index (76.6, W v. 75.9, Wo). Feed dry matter intake (DMI) was similar between diets (20.2 kg/day), but milk production and feed efficiency were lower with RM. Under W conditions, higher fat content and total solids of milk were observed with the RM-based diet, while crude protein and lactose were higher with MS. The Wo conditions increased body surface temperature (BS) in cows fed MS. The rectal temperature (RT) was higher with RM. The BS, RT and respiratory rate were higher at 14.00 h (34.9, 38.6 °C and 58.2 breaths/min) than at 09.40 h. The RM-based diet maintained DMI and milk composition, but not milk production. The use of the cooling system led to higher DMI and feed N efficiency use.

Whole-crop maize forage was ensiled without inoculant (control), inoculated with Lactobacillus buchneri and L. plantarum at a rate of 1 × 105 cfu/g fresh forage per bacterium (LBLP), or inoculated with Bacillus subtilis and L. plantarum at a rate 1 × 105 cfu/g fresh forage per bacterium (BSLP) with the goal to investigate the growth performance of finishing feedlot lambs. Thirty Dorper × Santa Ines lambs (29 ± 3.5 kg initial body weight) were used in the feedlot programme and assigned (n = 10) to one of three diets containing control, LBLP or BSLP silages in a 60:40 forage:concentrate ratio. Inoculation of maize silage did not alter dry matter intake (overall mean = 1.16 kg/day) and average daily gain (overall mean = 0.217 kg/day) of lambs. Consequently, feed efficiency remained unchanged. Inoculation of maize silage did not alter carcass and meat traits of lambs, with the exception of meat colour, wherein yellowness (b*) decreased by feeding LBLP and BSLP diets compared with the untreated diet. Regarding ruminal fermentation, there was an interaction between diets and the interval at which ruminal fluid was sampled for determining total volatile fatty acid concentration, but inoculation yielded no obvious results. In conclusion, the use of diets based on maize silage inoculated with L. plantarum combined with either L. buchneri or B. subtilis did not display relevant effects on growth performance of lambs; this response might be related to the limited impact of these bacterial inoculants on silage composition.

The effects of different dietary levels of maize silage (10% v. 36% DM) and group size (7 v. 14 animals) were assessed on growth performance and in vivo digestibility of 28 male fattening buffaloes. In addition, the effects of diet on meat quality and group size on behaviour and immune response were separately evaluated. Animals were weighed and assigned to three groups. The high silage – low size group (HL) was fed a total mixed ration (TMR) containing 36% DM of maize silage and consisted of seven animals (age 12.7±2.6 months; BW 382.2±67.7 kg at the start of the study). The low silage – low size group (LL) was fed a TMR containing 10% DM of maize silage and consisted of seven animals (age 13.0±2.7 months; BW 389.4±72.3 kg). The high silage – high size group (HH) was fed the 36% maize silage DM diet and consisted of 14 animals (age 13.9±3.25 months; BW 416.5±73.9 kg). Total space allowance (3.2 indoor+3.2 outdoor m2/animal) was kept constant in the three groups, as well as the ratio of animals to drinkers (seven animals per water bowl) and the manger space (70 cm per animal). Growth performance, carcass characteristics and digestibility were influenced neither by dietary treatment nor by group size, even if the group fed 36% maize silage diet showed a higher fibre digestibility. No effect of diet was found on meat quality. Group size did not affect the behavioural activities with the exception of drinking (1.04±0.35% v. 2.60±0.35%; P<0.01 for groups HL and HH, respectively) and vigilance (2.58±0.46% v. 1.20±0.46%; P<0.05 for groups HL and HH, respectively). Immune responses were not affected by group size.

During the winter feeding period in organic dairy production systems in the alpine and pre-alpine regions of Austria and its neighboring countries, maize silage is an energy-rich forage that is regularly included in grass-silage-based diets to improve the energy supply of the cows. Italian ryegrass (Lolium multiflorum Lam.) is also a high-energy fodder grass popular as forage for dairy cows, but it is rarely cultivated in Austrian organic agriculture. The two crops differ in their cultivation demands and characteristics. Italian ryegrass establishes rapidly and may reduce the risk of soil erosion. Italian ryegrass would be a beneficial addition to crop rotation, which is an essential tool in successful organic farming. In a 15-week feeding trial, Italian ryegrass silage and maize silage were fed to 22 lactating Holstein dairy cows. Organically produced Italian ryegrass silage and maize silage were included at a rate of 40% [of dry matter (DM)] in grass-silage-based mixed basal diets. The mixed basal diets were supplemented with modest amounts of additional concentrates (2.7–3.0 kg DM day−1). Owing to the higher energy content of maize silage as compared to Italian ryegrass silage, the maize diet provided more energy [6.3 MJ net energy for lactation (NEL) kg−1 DM] than the ryegrass diet (6.15 MJ NEL kg−1 DM). The protein supply of the maize diet and the ryegrass diet was intended to be equal, but in fact the protein content of the maize diet was significantly lower (122 g crude protein kg−1 DM) than that of the ryegrass diet (141 g kg−1 DM). When the maize diet was fed, feed intake, milk yield and milk protein content were significantly higher as compared to the ryegrass diet. Also, intake of crude protein was significantly lower when feeding the maize diet, and in combination with the higher milk protein yield, this enabled an efficiency of gross nitrogen (N) utilization as high as 0.304. This level of N efficiency can be considered as above average and was significantly and considerably higher than the level of 0.259 observed when the ryegrass diet was fed. Therefore, maize silage upholds its reputation as an ideal energy-rich component in grass-silage-based dairy cow diets.

The effects of (i) medium and high feed value (MFV and HFV) maize silages and (ii) MFV and HFV grass silages, each in combination with a range of concentrate feed levels, on the performance of finishing lambs were evaluated using 280 Suffolk-X lambs (initial live weight 36.1 kg). The MFV and HFV maize silages represented crops with dry matter (DM) concentrations of 185 and 250 g/kg, respectively, at harvest, and had starch and metabolisable energy (ME) concentrations of 33 and 277 g/kg DM and 9.6 and 11.0 MJ/kg, respectively. HFV and MFV grass silages had DM and ME concentrations of 216 and 294 g/kg and 11.0 and 11.5 MJ/kg DM, respectively. A total of 13 treatments were involved. The four silages were offered ad libitum with daily concentrate supplements of 0.2, 0.5 or 0.8 kg per lamb. A final treatment consisted of concentrate offered ad libitum with 0.5 kg of the HFV grass silage daily. Increasing the feed value of grass silage increased (P < 0.001) forage intake, daily carcass and live weight gains, final live weight and carcass weight. Increasing maize silage feed value tended to increase (P = 0.07) daily carcass gain. Increasing concentrate feed level increased total food and ME intakes, and live weight and carcass gains. There was a significant interaction between silage feed value and the response to concentrate feed level. Relative to the HFV grass silage, the positive linear response to increasing concentrate feed level was greater with lambs offered the MFV grass silage for daily live weight gain (P < 0.001), daily carcass gain (P < 0.01) and final carcass weight (P < 0.01). Relative to the HFV maize silage, there was a greater response to increasing concentrate feed level from lambs offered the MFV maize silage in terms of daily carcass gain (P < 0.05) and daily live weight gain (P = 0.06). Forage type had no significant effect on the response to increased concentrate feed level. Relative to the MFV grass silage supplemented with 0.2 kg concentrate, the potential concentrate-sparing effect of the HFV grass silage, and the MFV and HFV maize silages was 0.41, 0.09 and 0.25 kg daily per lamb, respectively. It is concluded that increasing forage feed value increased forage intake and animal performance, and maize silage can replace MFV grass silage in the diet of finishing lambs as performance was equal to or better (depending on maturity of maize at harvest) than that for MFV grass silage.

Phyto-oestrogens are believed to have a range of beneficial effects on predominant Western diseases. A few studies on phyto-oestrogens in milk exist and show that the composition can be affected by feeding. Therefore, the aim was to study how feeding of lucerne and grass/clover silages (GCSs) affects the concentration of phyto-oestrogens in bovine milk. Sixteen Danish Holstein cows were assigned to a 4 × 4 latin square design with four cows per treatment per period of 3 weeks. The four treatment diets were lucerne silage (LS), 2/3 lucerne silage and 1/3 maize silage (2/3LS), 1/3 lucerne silage and 2/3 maize silage (1/3LS) and GCS. Milk was collected at the end of each period and feed samples on day 6, 13 and 20 in each experimental period. Milk and pooled feed samples were analysed for the concentration of isoflavones, coumestans and lignans. The content of isoflavones was higher and the content of coumestrol lower in the GCS diet than in LS, 2/3LS and 1/3LS diets. For the LS, 2/3LS and 1/3LS diets, the concentration of coumestrol and secoisolariciresinol increased with the proportion of lucerne while the concentration of isoflavones was similar across the diets. The concentrations of the formononetin, daidzein and equol in the milk were significantly higher for the GCS diet than for the LS, 2/3LS and 1/3LS diets. In particular, the concentration of equol was 62–291 times higher for GCS. The concentration of coumestrol was significantly lower for the GCS diet compared to the LS, 2/3LS and 1/3LS diets. No pattern for the concentration of lignans was observed. In conclusion, a high concentration of isoflavones, particularly equol, and a low concentration of coumestrol were measured in the milk from the GCS diet. In contrast, a low concentration of isoflavones and a high concentration of coumestrol were measured in the milk from the LS, 2/3LS and 1/3LS diets. However, the concentration of phyto-oestrogens in bovine milk is low compared to food sources rich in phyto-oestrogens but the high concentration of equol could possibly be of therapeutic importance.

The literature implicates strongly that including energy supplements in dairy rations based on protein-rich forages increases performance and feed efficiency due to an improved and more balanced ruminal energy and protein supply. Therefore, both conventional and organic dairy farms primarily supplement roughages with concentrates, containing high proportions of cereal grains. However, considering the main principles of sustainable agricultural systems and nutrient cycles, the question of alternatives is raised. Therefore, the present study was conducted to compare grain and maize silage as energy sources in organic dairy cow rations. Two grass–clover silage-based diets, offered on an ad libitum basis, were supplemented either with 1 kg grain mixture plus 0.5 kg hay (treatment group G) or 2.1 kg maize silage (treatment group M) on a dry matter (DM) basis. The trial was carried out as a change-over design and lasted for 15 weeks. Intake of concentrates, DM and utilizable crude protein in the duodenum (uCP) were similar in both treatments. However, significant differences between treatments G and M were found for grass–clover silage dry matter intake (DMI) (13.4 versus 12.9 kg), forage DMI (14.6 versus 15.7 kg), crude protein (CP) intake (2885 versus 2801 g), ruminal nitrogen balance (RNB) (40 versus 29 g) and intake of neutral detergent fiber (NDF) (7630 versus 7900 g). Milk yield was not affected by treatment, but in treatment M, milk fat content was at 42.4 g kg−1, significantly higher, and milk urea concentration at 19.7 mg 100 ml−1, significantly lower, as compared with treatment G. Efficiency of N use (N in milk in % of N intake) tended to be improved in treatment M. Balances of energy and uCP (intake as a percentage of requirements) were unaffected by treatment.

The objectives of the two experiments were to determine the respective effects and interactions of diet type (grass v. maize diets) and physical activity (grazing v. zero grazing) on lipogenic enzyme activities and adipose cell size in subcutaneous, perirenal and intermuscular adipose tissues and on plasma metabolites and hormones in Charolais steers. After weaning, the steers were assigned to two (Experiment 1, n = 24) or three (Experiment 2, n = 24) groups, with steers in Experiment 1 grazed grass or indoors maize-silage-fed and steers in Experiment 2 grazed grass, indoors cut grass- or indoors maize-silage-fed. Both experiments lasted for 23 months. All grass-fed animals were fed grass silage during the two winter seasons. During the two summer seasons, steers fed on grass were rotationally grazed on a perennial rye-grass pasture while steers fed on cut grass were fed indoors on freshly cut grass alone. Steers fed on maize silage were fed maize silage indoors during the entire experiment. All animals were reared for similar body weight and growth rates and slaughtered at the same age (31 to 32 months). Activities of lipogenic enzymes were significantly lower in the three adipose tissue sites of steers fed cut grass compared with maize silage, although there were less-marked effects in intermuscular adipose tissue. Plasma insulin and glucose concentrations were also lower in steers fed cut grass whereas plasma leptin concentration was similar. As body fat content was not affected by nutritional treatment, it is suggested that the decrease in potential lipogenic activity was associated with the nature of the diet and not to differences in available net energy. In other respects, grazed grass compared with eating cut grass did not affect lipogenic enzyme activities but decreased plasma leptin concentrations in the older steers and increased plasma non-esterified fatty acids and glucose concentrations without affecting adipose tissue weight and adipose cell size.

Maize silage-based diets with three dietary crude protein (CP) supplements were offered to 96 finishing cattle of contrasting breed (Holstein Friesian (HF) v. Simmental × HF (SHF)) and gender (bull v. steer) housed in two types of feeding system (group fed v. individually fed). The three protein supplements differed either in CP or protein degradability (degradable (LUDP) v. rumen undegradable (HUDP)) and provided CP concentrations of 142 (Con), 175 (LUDP) and 179 (HUDP) g/kg dry matter (DM) respectively, with ratios of degradable to undegradable of 3.0, 1.4 and 0.9:1 for diets Con, LUDP and HUDP, respectively. DM intakes were marginally higher (P = 0.102) for LUDP when compared with Con and HUDP. Rates of daily live-weight gain (DLWG) were higher (P = 0.005) in LUDP and HUDP when compared with Con. HF had higher DM intakes than SHF although this did not result in any improvement in HF DLWG. Bulls had significantly better DM intakes, DLWG and feed conversion efficiency than steers. Conformation scores were better in SHF than HF (P < 0.001) and fat scores lower in bulls than steers (P < 0.001). There was a number of first order interactions established between dietary treatment, breed, gender and housing system with respect to rates of gain and carcass fat scores.

A randomised design involving 66 continental cross beef steers (initial live weight 523 kg) was undertaken to evaluate the effects of the inclusion of maize or whole-crop wheat silages in grass silage-based diets on animal performance, carcass composition, and meat quality of beef cattle. Grass silage was offered either as the sole forage or in addition to either maize or whole-crop wheat silages at a ratio of 40:60, on a dry matter (DM) basis, alternative forage: grass silage. For the grass, maize, and whole-crop wheat silages, DM concentrations were 192, 276, and 319 g/kg, ammonia-nitrogen concentrations were 110, 90, and 150 g/kg nitrogen, starch concentrations were not determined, 225, and 209 g/kg DM and in vivo DM digestibilities were 0.69, 0.69, and 0.58; respectively. The forages were offered ad libitum following mixing in a paddle type complete diet mixer wagon once per day, supplemented with either 3 or 5 kg concentrates per steer per day, in two equal feeds, for 92 days. For the grass, grass plus maize and grass plus whole-crop wheat silage-based diets food intakes were 8.38, 9.08, and 9.14 kg DM per day, estimated carcass gains were 514, 602, and 496 g/day and carcass weights were 326, 334, and 325 kg; respectively. Altering the silage component of the diet did not influence carcass composition or meat eating quality. Increasing concentrate feed level tended ( P = 0.09) to increase estimated carcass fat concentration and increased sarcomere length ( P < 0.05), and lean a* ( P < 0.01), b* ( P < 0.05), and chroma ( P < 0.01). There were no significant silage type by concentrate feed level interactions for food intake, steer performance, carcass characteristics or meat eating quality. It is concluded that replacing grass silage with maize silage increased carcass gain, and weight due to higher intakes, and improved utilisation of metabolisable energy. Whilst replacing grass silage with whole-crop wheat silage increased live-weight gain, the reduced dressing proportion resulted in no beneficial effect on carcass gain, probably due to increased food intakes of lower digestible forage increasing gut fill. Meat quality or carcass composition were not altered by the inclusion of maize or whole-crop silages in grass silage based diets.

Advancing maturity of forage maize is associated with increases in the proportion of dry matter (DM) and starch and decreases in the proportions of structural carbohydrates in the ensiled crop. Three maize silages (286 (low, L), 329 (medium, M) and 379 (high, H) g DM per kg fresh weight) plus a concentrate formulated to give isonitrogenous intakes were offered to Holstein-Friesian steers fitted with a cannula in the dorsal sac of the rumen and a ‘T’ piece cannula in the proximal duodenum in an experiment with a cross-over design that allowed four collection periods. Nutrient flow to the duodenum was estimated using chromium-EDTA. Steers consumed approximately 0·6 kg DM per day less of diet L compared with the other two diets (P=0·026), resulting in less DM being digested (P=0·005) but digestibility did not differ between diets. Similar results were obtained for organic matter. There were no differences between diets in the intake or digestibility of neutral-detergent fibre. Intake, duodenal flow and faecal output of starch were greater for steers offered diets M and H compared with those given diet L (P<0·05). In all diets rumen digestion contributed to over 90% of total digestion of starch, although rumen digestibility declined significantly with advancing maize maturity (P=0·002). Molar proportions of acetic acid were higher in diet H (P<0·05) whilst proportions of propionic acid and n-butyric acid were higher in diets M and L. There were no significant differences between diets in mean rumen pH or ammonia concentrations. Mean circulating concentrations of insulin were higher (P=0·009) in cattle given diets L and M compared with diet H. There were no differences between diets in the mean circulating concentration of growth hormone, or the frequency, amplitude and duration of growth hormone pulses, or the mean circulating concentrations of IGF-1. Changes in forage composition that accompany advancing maize maturity affect overall silage digestion and circulating concentrations of insulin.

Simmental × Holstein-Friesian steers were offered four forage diets. These comprised grass silage (G); proportionately 0·67 grass silage, proportionately 0·33 maize silage (GGM); 0·33 grass silage, 0·67 maize silage (MMG); maize silage (M) from 424 (s.d. = 11·5) kg to slaughter at a minimum weight of 560 kg. Forages were mixed and offered ad libitum. Steers were offered 2 kg of a concentrate daily, the concentrate being formulated such that all steers had similar crude protein intakes across dietary treatments. A sample of steers was slaughtered at the beginning of the experimental period to allow the calculation of the rate of gain of the carcass and its components. Carcass dissection of a sample of steers allowed the development of a prediction equation of carcass composition based on thoracic limb dissection of all carcasses. Forage dry matter intake and live-weight gain increased linearly as maize silage replaced grass silage in the forage mixture, resulting in improvements in food conversion ratio (all P = 0·001). Killing-out proportion increased with maize silage inclusion (P < 0·001) but fat and conformation scores did not differ significantly between diets. However, increasing maize inclusion in the diet resulted in a greater weight (P = 0·05) and proportion (P = 0·008) of fat in the carcass, and significant increases in internal fat deposition. The inclusion of maize led to a progressive increase in the daily gains of carcass (P < 0·001), and significant increases in the daily gains of both fat (P < 0·001) and lean tissue (P < 0·001). Fat colour was more yellow in cattle given diets G and GGM than diets MMG and M(P < 0·001) and colour intensity was lower on diet M than the other three diets (P < 0·001). There were no significant differences in any aspects of eating quality between diets. Therefore, maize silage has the potential to reduce the time taken for finishing beef animals to achieve slaughter weight with no apparent detrimental effects on subsequent meat quality.

Advancing maturity of forage maize is associated with increases in the proportion of dry matter (DM) and starch, and decreases in the proportions of structural carbohydrates in the ensiled crop. This experiment investigated the effects of three maize silages of 291 (low), 339 (medium) and 393 (high) g DM per kg fresh weight on the performance of 48 Simmental X Holstein-Friesian cattle. Equal numbers of steers (mean start weight = 503 (s.d. 31.3) kg) and heifers (mean start weight = 378 (s.d. 11.2) kg) were offered individually isonitrogenous diets composed of the three silages plus a protein supplement with minerals once daily until slaughter at the target live weight of 575 and 475 kg for steers and heifers, respectively. Intake was reduced on the low diet (P < 0.01) compared with the other two treatments. Dietary starch intake increased by a total of 1 kg/day between low and medium diets but by only 0.2 kg/day between medium and high diets. Unlike starch intake, total neutral-detergent fibre intake showed no significant difference (P > 0.05) between diets. There were no differences in live-weight gain between treatments but differences (F < 0.05) in food conversion efficiency indicated relative gains of 115,100 and 102 g gain per kg DM intake for diets low, medium and high, respectively. There were no differences between diets in carcass weights, fat score and overall conformation.

A naturally occurring zeolite (Anzymite™) was added to a diet containing 350 g maize silage per kg (which was treated with 10 g urea per kg (fresh weight)), 375 g barley and 275 g alfalfa hay per kg. Effect of inclusion of zeolite (0, 30 and 60 g/kg diet) on diet digestibility, ruminal fluid acidity and ammonia concentration, blood urea nitrogen level, and feedlot performance was studied in Mehraban ram lambs. The diets were given ad libitum. Digestibility coefficients of dietary dry matter and crude protein were significantly increased by zeolite (P < 0·05). The diet containing 30 g zeolite per kg had higher neutral-detergent fibre digestibility compared with the control (P < 0·05). Over all sampling times, the ruminal fluid of the sheep given the 30-g/kg zeolite diet had the highest and those given the 60-g/kg zeolite diet had the lowest pH values (P = 0·03). Before feeding, ruminal ammonia concentration was low for all treatments (4 to 8 mg/dl). At 4 h after feeding, the control diet had the lowest ruminal ammonia concentration (5·5 mg/dl) which was significantly lower than the values for zeolite diets (35 to 39 mg/dl). Blood urea nitrogen (BUN) level increased post feeding for all diets. At 4 h post feeding, the level for the control diet was significantly higher than for the zeolite diets, but at 6 h post feeding, the level of BUN was higher with 60 g zeolite per kg diet. Daily dry-matter intake for the 60 g zeolite per kg diet was significantly higher than for the control. Backfat depth in the 60 g zeolite group was significantly less than the control group. Pelvic and pericardial fats were significantly higher for the zeolite groups. Fat-tail weight in the 60 g/kg of zeolite group was significantly higher than in the 30 g zeolite and control groups. The findings indicated that, in spite of some improvements in digestibility and rumen fermentation pattern, addition of zeolite to the diet of feedlot Mehraban lambs, under the conditions of this experiment, was not advantageous.

To examine the effects of manipulating the amount and ruminal degradability of starch on food intake, milk production and digestion in the rumen of lactating dairy cows, cracked wheat (CW) and sodium hydroxide-treated wheat (SW) were compared when offered with either immature (IM) or mature (MM) maize silage given in a 3: 1 dry matter (DM) ratio with grass silage. The total mixed ration (TMR) contained (kg/t DM basis) forage 600, wheat (CW or SW) 170, rapeseed meal 100, soya-bean meal 100, molasses/urea supplement 30 and minerals and vitamins were added at 20 kg/t diet DM. In experiments 1 and 2 respectively, 16 multiparous Holstein-Friesian cows and four similar cows with duodenal and ruminal cannulas were offered four diets (IMCW, IMSW, MMCW, MMSW) in 4 ✕ 4 Latin-square designs. In experiment 3, the in sacco degradability of CW and SW was measured in the rumen of three lactating fistulated cows. In experiment 1 total DM intake was 0·7 kg/day higher and milk yield was 0·5 kg/day higher with MM than IM silage but the increases were not significant and type of wheat had no effect. Milk fat content was reduced by MM silage (P < 0·05) but was unaffected by type of wheat. For milk protein content SW caused a non-significant increase with IM but a decrease (P < 0·05) with MM silage (interaction P < 0·05). There were no significant effects on yield of fat or protein. Neutral-detergent fibre digestibility in the rumen was unaffected by the treatments. Starch intake increased (P < 0·05) with MM silage when compared with IM silage and was accompanied by an increase (P < 0·01) in starch flow to the duodenum and in the amount (P < 0·001) digested in the rumen, although there was no significant change in rumen digestibility. Replacing CW with SW increased starch flow to the duodenum (P < 0·05) and reduced rumen digestibility (P < 0·05). Although the amount of total nitrogen (TN) digested in the rumen and rumen digestibility decreased (P < 0·01) with crop maturity, the flow of TN and non-ammonia nitrogen to the duodenum was unaffected. Total tract digestibility of DM was unaffected by treatments. Although the amount of starch digested in the total tract increased for MM compared with IM silage, reflecting the higher starch intake, total tract starch digestibility was unaffected by treatment and averaged 0·972. There were no main treatment effects on daily mean pH, concentration of ammonia or concentration or molar proportions of volatile fatty acids in the rumen. With SW, effective degradability (outflow rate of 0·08 per h) for both DM and starch was reduced when compared with CW. In conclusion the studies confirm that SW is more slowly fermented than CW and can increase the supply of starch to the duodenum. However the concept that increasing starch supply to the duodenum by a combination of MM silage and SW is likely to be beneficial to milk protein yield or concentration is not established under the present dietary regimen.

Six multiparous Holstein-Friesian cows were offered a total mixed ration based on maize silage in a repeated measure design to evaluate the partition of gross energy (GE) during early to mid lactation. Four measurements were made at 6-week intervals with energy and nitrogen balances carried out in open-circuit respiration chambers over 6 days during lactation weeks 6, 12, 18 and 24. The intakes of total diet dry matter (DM) corrected for volatile losses (VCDM), organic matter (OM) and GE declined significantly (P < 0•01) as lactation progressed, although apparent digestibility of these fractions was not altered, resulting in a significant (P < 0•01) decline in digestible nutrient intake at each stage of lactation. Methane and urine energy losses were not significantly affected, resulting in significantly (P < 0·001) higher amounts of digestible energy (DE) partitioned to methane and urine as lactation progressed with associated significant reductions in metabolizable energy (ME) intake (MEI) (P < 0·01) and ME as a proportion of DE (P < 0·001) and GE (q) (P < 0·05). With advancing lactation there was a significant (P < 0·001) increase in the amount of ME partitioned to heat (HP/MEI), but no significant change in the amount partitioned to milk and tissue. Individual values for diet metabolizability (ME/GE) at actual (production) levels (qa) (mean 0·625 MJ/MJ) were corrected to an equivalent value at maintenance (qmc) (mean 0·666 MJ/MJ). The overall ME intakes (MJ/day) were: ad libitum, 246, corrected for level of feeding effect, 263, with a predicted ME requirement according to AFRC (1993) (MER93) of 242. Substitution of the calculated qmc into the predictive equations (AFRC, 1993) resulted in a mean maintenance requirement of 57·6 MJ/day (0·464 MJ/kg M0·75/day) whilst the mean value derived from the linear model describing the experimental data was 82·5 MJ/day (0·664 MJ/kg M0·75/day). The mean efficiencies of utilization of ME for milk production derived from AFRC (1993) and the linear regression model were 0·653 MJ/MJ and 0·625 MJ/MJ respectively.

To evaluate the effect of crop maturity on digestion of maize silage in the rumen and post-ruminal digestive tract, four multiparous Holstein-Friesian cows fitted with a simple cannula in the proximal duodenum and a rumen cannula were offered four diets in a 4 ✕ 4 Latin-square design. Forage maize (cv. Hudson) was harvested and ensiled at target dry matter (DM) contents of 230, 280, 330 and 380 g per kg fresh weight (FW) to provide a range of starch contents. The mean values for volatile-corrected DM (VCDM) and starch content of the four maize silages as given were 221, 277, 308 and 372 g/kg FW and 173, 257, 328 and 382 g/kg VCDM respectively. Grass silage (GS) containing 250 g VCDM per kg FW was produced from the primary growth of a perennial ryegrass sward. The diets were 8·7 kg DM per day of a dairy concentrate supplement with one of four forage treatments offered ad libitum. The forage treatments were a 3 : 1 DM ratio of maize silage with GS, designated as T23, T28, T33 and T38. Each period lasted 6 weeks with rumen and duodenal samples being taken over 3 days in week 4 and faeces being collected in respiration chambers over 6 days in either week 5 or 6. Milk yield tended to increase with advancing maturity (30·5, 31·8, 32·5 and 32·3 kg/day) but individual treatment differences were not significant. DM intake increased from 19·62 to 21·30 kg/day (P < 0·05) but there were no significant effects on digestibility in the rumen, post-ruminal tract or total tract. Digestibility of neutral detergent fibre in the rumen declined with increasing starch content in the maize silage (P < 0·05) but total digestibility was not significantly affected. Starch intake increased from 3·11 to 5·04 kg/day (P < 0·001), duodenal flow from 0·40 to 0·89 kg/day (P < 0·01) and the amounts digested in the rumen and post-ruminal tract respectively from 2·72 and 0·34 kg/day to 4·16 and 0·71 kg/ day (P < 0·01). However the only significant effect on starch digestibility was a small fall in total digestibility from a mean of 0·981 for T23, T28 and T33 to 0·966 for T38. There were no treatment effects on nitrogen digestion. The molar proportions of acetic acid and n-caproic acid decreased and that of n-butyric acid increased with advancing maturity. It is concluded that the changes in composition of maize silage with increasing maturity result in large increases in the contribution of starch to DM digested in the rumen but only small differences in rumen fermentation. Post-ruminal starch digestion doubles but this is due to the increased starch concentration of the silage rather than major changes in digestion and the amount is small compared with that likely to result from feeding maize grain.

Four multiparous Holstein-Friesian cows fitted with simple cannulas in the proximal duodenum and the rumen were offered four diets in a 4 ✕ 4 Latin-square design to evaluate the effect on energy and nitrogen balance of crop maturity of maize when offered as ensiled food with grass silage and a concentrate. Forage maize (cv. Hudson) was ensiled at target dry matter (DM) contents of 230, 280, 330 and 380 g per kg fresh weight (FW). The mean values for volatile corrected DM (VCDM) and starch content of the maize forages as given were 226, 278, 319 and 357 g/kg FW and 180, 263, 327 and 401 g/kg VCDM respectively. Grass silage (GS) containing 247 g VCDM per kg FW was produced from the primary growth of a perennial ryegrass sward. The diets comprised 8·7 kg DM concentrate per day with one of four forage treatments offered ad libitum, in a 3 : 1 DM ratio of maize silage with GS, designated T23, T28, T33 and T38. Each period was of 6 weeks with energy and nitrogen balances conducted in respiration chambers over 6 days in either week 5 or 6. There were no significant effects of maturity on DM intake. Changes in milk yield and composition were not significant but milk protein yield increased significantly (P < 0·05) with maize maturity up to T33 and was linearly related (P < 0·05) to changes in maize silage starch and neutraland acid-detergent fibre (NDF, ADF) content. Total starch intake increased significantly (P < 0·01) with maturity but apparent digestibility of starch was significantly (P < 0·05) reduced only with the most mature maize silage (T38). NDF and ADF intake and amounts digested were not significantly different despite a numerical decline with stage of maturity. Total nitrogen intake and apparent digestibility were not significantly different although there were significant differences (P < 0·05) in the amount of nitrogen excreted as urine, which was greatest on T23 and least on T33, and milk which was least on T23 and greatest on T33. Mean gross energy (GE) intake increased by 17 MJ/day from T23 to T33 but the differences were non-significant. Faecal energy output on T23 was significantly lower (P < 0·05) than the other treatments whilst urine energy on T23 was significantly higher (P < 0·05) compared with T33. Methane energy losses were not significantly different. There were no significant differences between treatments in either GE digestibility or metabolizability, digestible or metabolizable energy (ME) intakes or in the partition of ME to heat, tissue or milk. The calculated ME concentrations of the maize silages were not significantly different with an overall mean of 12·3 MJ/kg VCDM estimated at maintenance intake, or 0·63 MJ/MJ GE. Changes in maize silage composition resulted in a doubling of the ratio of digested starch to digested NDF (0·66, 0·94, 1·10 and 1·21) for treatments T23 to T38 respectively. Despite this large change in digested nutrients no differences in the efficiency of energy utilization were detected.

Fifty-five multiparous Holstein-Friesian cows were used in a 20-week continuous design study to determine the effect of maize silage maturity on food intake and milk production. Forage maize (cv. Hudson) was harvested and ensiled at target dry matter (DM) contents of 230 (T23), 280 (T28), 330 (T33) and 380 (T38) g per kg fresh weight (FW). The mean values for volatile-corrected DM (VCDM), starch, neutral-detergent fibre (NDF), crude protein and predicted metabolizable energy (ME) content of the four maize silages were 226, 290, 302 and 390 g/kg FW, 114, 274, 309 and 354 g/kg VCDM, 574, 447, 431 and 448 g/kg VCDM, 96, 80, 74 and 75 g/kg VCDM and 10·3, 11·5, 11·6 and 11·2 MJ/kg DM, respectively. Grass silage containing 296 g VCDM per kg FW was produced from the primary growth of a perennial ryegrass sward. At week 3 of lactation cows were allocated to one of five forage treatments offered ad libitum. The forage treatments were either grass silage alone (TGS) or a 3 : 1 DM ratio of maize and grass silage designated as T23, T28, T33 and T38. All cows also received 8·7 kg DM per day of a dairy concentrate. Forage VCDM intake for TGS was lower (P < 0·001) than for T23 to T38. Increasing maize silage DM content from 226 (T23) to 290 (T28) g/kg increased (P < 0·05) forage VCDM intake from 10·9 to 13·3 kg/day but a further increase to 390 (T38) g/kg tended to reduce VCDM intake. When compared with TGS, the inclusion of maize silage increased milk yield from 28·0 kg/day to 29·4, 32·7, 33·0 and 30·8 kg/day for T23 to T38, respectively, the increases being significant for T28 to T38. However, milk yield was reduced (P < 0·05) when the DM content of the maize silage increased from 302 to 390 g/kg. Increasing maize silage DM content from T23 to T33 reduced (P < 0·05) milk fat content from 45·8 to 41·8 g/kg, which was also lower (P < 0·05) than for TGS. The inclusion of maize silage increased fat yield with a significant difference (P < 0·05) between TGS and T28. The inclusion of maize silage increased milk protein content (P < 0·05) and protein yield (P < 0·001) when compared with TGS. While increasing maize silage maturity did not affect (P > 0·05) milk protein content, protein yield was higher (P < 0·05) for the two intermediate DM contents. There were no treatment effects on body condition score. It is concluded that the changes in composition of maize silage with increasing maturity, which are associated with increased starch and reduced NDF content, resulted in large increases in food intake and yield of milk and protein as crops matured from T23 to T33. However, when crop maturity increased further to T38 there was a tendency for DM intake and yield of milk and protein to decline.