Variables associated with peripartum traits in dairy cows. I. Effect of dietary forages and disorders on voluntary intake of feed, body weight and milk yield

Daily voluntary intakes of feed by each of 89 Holstein cows were compared between day 220 of gestation and day 30 postpartum over a 21-month period. Diets designed to meet NRC requirements and which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were compared prepartum (27 to 0 days), peripartum (1 day before to 3 days after calving) and postpartum (days 4 to 30 postpartum). Mixed rations, fed during lactation, were 60% forage and 40% concentrate dry matter (DM). Cow management was similar to commercial operations. The experimental hypothesis was that pre-disposition for partum and postpartum disorders (abnormal) could be related either to voluntary intake of different diets or to physical traits. Intakes (DM or estimated net energy) across diets decreased 30% between days 7 and 1 prepartum and averaged 18% and 20% lower peripartum and postpartum, respectively, in abnormal cows than in control cows. Seasonal effects on intakes were significant. In general, changes in body weight and condition and differences in udder edema and milk yield reflected intakes. The results support the original hypothesis.     

Variables associated with peripartum traits in dairy cows. III. Effect of diets and disorders on certain blood traits

BLood samples were collected from 89 Holstein cows on days 220 and 250 of gestation, within 24 hr prepartum and postpartum and on day 30 postpartum. Balanced diets which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were fed from day 220 of gestation to day 30 postpartum. The purpose was to determine if variations in certain blood traits were indicative of peripartum and postpartum disorders. The blood traits evaluated were concentrations of plasma total protein, whole blood hemoglobin, packed cell volume, and white blood cells, and serum glutamic oxalacetic transaminase (SGOT), glucose, urea nitrogen, calcium, inorganic phosphorus, magnesium, potassium and sodium. No blood trait was useful to predict a disorder prior to its visual signs with one possible exception. Serum glucose and calcium were lower and SGOT and magnesium were higher peripartum which was prior to death of three cows from fat cow syndrome.     

Effect of wheat hay particle size and replacement of wheat hay with wheat silage on rumen pH,rumination and digestibility in ruminally cannulated non-lactating cows

This study examined the effects on intake, diurnal rumen pH changes, rumination and digestibility of feeding ruminally cannulated non-lactating cows in a Latin square design (four cows×four periods) with four total mixed rations (TMRs) typical for lactating cows. TMRs were based on: long wheat hay or short wheat hay, wheat silage or wheat silage+1.5% NaHCO₃ buffer, as the sole roughage source (30% of TMR dry matter (DM)). The level of physically effective NDF remaining above the 8 mm screen (peNDF) was similar in the long hay and silage-based TMRs (9.45% to 9.64% of DM) and lower in the short hay TMR (7.47% of DM). The four TMRs were offered individually at 95% of ad libitum intake to avoid orts within 24 h. Cows fed long hay consumed less DM than the short hay and silage groups (9.6 v. 10.5 and 10.8 kg/day, respectively) and sorted against large hay particles at 12 h post-feeding. Under the limitations of this study (non-lactating cows fed at restricted intake) short hay TMR prevented sorting within 12 h post-feeding, encouraged rumination per kg peNDF ingested, and had higher average rumen pH (6.24), whereas preventing sub acute ruminal acidosis (SARA, defined as pH<5.8 for at least 5 h/day). In contrast, the long hay and silage-based groups were under SARA. In vitro methane production of rumen fluid was higher in the hay-fed cows than in their silage-fed counterparts, and in all treatments lower at 1 h pre-feeding than at 6 h post-feeding. In vivo DM and NDF digestibility were similar for the short hay and silage TMRs, and higher than those of the long hay TMR. Under the conditions of this study, addition of 1.5% buffer to the wheat silage TMR had no effect on intake, rumen pH, creation of SARA and digestibility.     

Effect of feeding long or short wheat hay v. wheat silage in the ration of lactating cows on intake,milk production and digestibility

The objective of this study was to evaluate in lactating cows the effect of either chopping or ensiling of wheat roughage on: intake, digestibility, lactation performance and animal behavior. Three groups of 14 lactating cows each, were fed total mixed rations (TMRs) based on either long wheat hay (HL), short wheat hay (HS) or wheat silage (SI), as the sole roughage source (30% of TMR dry matter (DM)). Parameters examined: sorting behavior, DM intake, milk yield and composition, rumination, recumbence, average daily rumen pH, digesta passage rate, and in-vivo digestibility. Performance data was summarized by day and analyzed using a proc-mixed model. The content of physically effective neutral detergent fiber (peNDF) was similar in the HL and SI and lower in the HS, resulting in similar differences among the three corresponding TMRs. In vitro DM digestibility of wheat silage was higher than that of the two hays (65.6% v. 62.8%) resulting in higher in vitro DM digestibility of the SI-TMR compared with the hay-based TMRs (79.3 v. 77.0%). HS-TMR was better than HL- or SI-TMRs at preventing feed sorting by cows after 12 or 24 h eating of the diets. Cows fed HS-TMR consumed more DM and NDF but less peNDF than the other two groups. Average daily rumen pH was similar in the three groups, but daily rumination time was highest in the cows fed HS-TMR. Rumen retention time was longest in cows fed HL-TMR. DM digestibility in cows fed SI-TMR was higher than that of HS and HL groups (65.2%, 61.8% and 62.4%, respectively), but NDF digestibility was similar in the three treatments. The highest intake of digestible DM was observed in cows fed SI-TMR, HS cows were intermediate and HL cows were the lowest. Consequently, cows fed SI-TMR had higher yields of milk, 4% fat corrected milk and energy-corrected milk (47.1, 42.9 and 43.2 kg/day, respectively) than cows fed HS-TMR (45.7, 41.0 and 41.0 kg/day, respectively) or HL-TMR (44.1, 40.3 and 40.3 kg/day, respectively). Net energy production (NE_L+M+gain) per kg DM intake was highest in the SI-TMR, lowest in the HS-TMR and intermediate in the HL-TMR (1.52, 1.40 and 1.45, respectively). Animal welfare, as expressed in daily recumbence time and BW gain was similar in the SI and HS groups and higher than the HL cows.     

Effect of substituting wet corn gluten feed and corn stover for alfalfa hay in total mixed ration silage on lactation performance in dairy cows

Wet corn gluten feed (WCGF) is a high moisture feed containing rapidly digestible, non-forage fiber and protein. The objective of this study was to investigate the effect of substituting WCGF and corn stover for alfalfa hay in total mixed ration (TMR) silage on lactation performance and nitrogen balance in dairy cows. Nine multiparous Holstein dairy cows (BW = 532 ± 28.9 kg and day in milk = 136 ± 5.6 d; mean ± SD) were used in a replicated 3 × 3 Latin square design with 21-d periods (14 d of diet adaption and 7 d of sample collection). Groups were balanced for parity, day in milk, and milk production and consumed one of three treatment diets during each period. The treatment diets were fed as TMR and contained similar concentrate mixtures and corn silage but different proportions of roughage and WCGF. The three treatments were: (1) 0% WCGF, 0% corn stover, and 22.1% alfalfa hay (0% WCGF); (2) 6.9% WCGF, 3.4% corn stover, and 11.8% alfalfa hay (7% WCGF); and (3) 13.3% WCGF, 4.9% corn stover, and 3.9% alfalfa hay (13.3% WCGF). Compared to the 0% WCGF diet, the cows fed the 7% and 13.3% WCGF diets had a higher milk yield and concentration of milk fat, protein, lactose, and total solids. Effective degradability of DM was higher in the cows fed the 7% and 13.3% WCGF diets than it was with the 0% WCGF diet. Cows fed the 13.3% WCGF had a higher CP effective degradability and a lower rumen undegraded protein than cows fed the 0% WCGF diet. The concentration of ruminal volatile fatty acids and ammonia-N was higher in cows fed the 7% and 13.3% WCGF diets than cows fed the 0% WCGF diet. The fecal N was lower in cows fed the 7% and 13.3% WCGF diets than it was in cows fed the 0% WCGF diet. Milk N secretion and milk N as a percent of N intake were higher in cows fed the 13.3% WCGF diet than cows fed the 0% and 7% WCGF diets. In conclusion, it appears that feeding a TMR silage containing WCGF and corn stover in combination, replacing a portion of alfalfa hay, may improve lactation performance and nitrogen utilization for lactating dairy cows.     

Effects of feeding high-quality hay with graded amounts of concentrate on feed intake,performance and blood metabolites of cows in early lactation

Dairy cows are commonly fed energy-dense diets with high proportions of concentrate feedstuffs to meet the increased energy needs of early lactation. However, feeding large amounts of concentrates may cause rumen acidosis and impact cow health. The hypothesis tested was that the energy supply and metabolic health of early-lactation Simmental cows can be maintained when high-quality hay rich in water-soluble carbohydrates (WSC) and crude protein (CP) is fed, despite the proportion of concentrates in the diet being reduced or even excluded. Twenty-four Simmental cows were allocated to one of four feeding groups beginning 10 d before the expected calving date, until 28 d thereafter. The feeding groups were 60CH (60% conventional fibre-rich hay plus 40% concentrate feed), 60HQH (60% high-quality hay plus 40% concentrate feed), 75HQH (75% high-quality hay plus 25% concentrate feed) and 100HQH (100% high-quality hay). The fibre-rich hay and high-quality hay differed in WSC content (110 g vs. 198 g of dry matter (DM)), neutral detergent fibre (646 g vs. 423 g of DM) and CP (65 g vs. 223 g of DM). Individual feed intake and milk production were monitored daily, and blood samples were collected weekly. Dry matter intake (DMI) and milk yield increased post partum, but 4 weeks post partum, the DMI of cows fed 100HQH only reached a daily mean DMI of 18.6 kg, whereas the DMI of the other groups averaged 21.9 kg (p < 0.046). The negative energy balance was less pronounced in cows fed 75HQH since they showed similar milk yields to the cows fed 60CH and 100HQH, but their energy intake was higher. Concentrations of milk components were similar across rations 60CH, 60HQH and 75HQH, as were most of blood parameters. Cows fed 100HQH responded to the energy deficit post partum with a higher ratio of non-esterified fatty acids to cholesterol and a higher concentration of ß-hydroxybutyrate (significant in comparison to cows fed 75HQH, p < 0.05). In conclusion, feeding high-quality hay with a WSC content of 20% in DM has the potential to decrease the proportion of concentrates in dairy cow feeding in early lactation, but cannot fully replace their supplementation due to a limited rumen capacity for forage intake.     

The effect of varying proportion and chop length of lucerne silage in a maize silage-based total mixed ration on diet digestibility and milk yield in dairy cattle

The objective was to assess the effects of inclusion rate and chop length of lucerne silage, when fed in a total mixed ration (TMR), on milk yield, dry matter (DM) intake (DMI) and digestion in dairy cows. Diets were formulated to contain a 50 : 50 ratio of forage : concentrate (DM basis) and to be isonitrogenous (170 g/kg CP). The forage portion of the offered diets was comprised of maize and lucerne silage in proportions (DM basis) of either 25 : 75 (high Lucerne (HL)) or 75 : 25 (low lucerne (LL)). Lucerne was harvested and conserved as silage at either a long (L) or short (S) chop length. These variables were combined in a 2×2 factorial arrangement to give four treatments (HLL, HLS, LLL, LLS) which were fed in a Latin square design study to Holstein dairy cows in two separate experiments. In total, 16 and 8 multiparous, mid-lactation cows were used in experiments 1 and 2, respectively. To ensure sufficient silage for both experiments, different cuts of lucerne silage (taken from the same sward) were used for each experiment: first cut for experiment 1 (which was of poorer quality) and second cut for experiment 2. Dry matter intake, milk yield and milk composition where measured in both experiments, and total tract digestibility and nitrogen (N) balance were assessed using four cows in experiment 2. In experiment 1, cows fed LL had increased DMI (+3.2 kg/day), compared with those fed HL. In contrast, there was no difference in DMI due to lucerne silage inclusion rate in experiment 2. A reduction in milk yield was observed with the HL treatment in both experiment 1 and 2 (−3.0 and −2.9 kg/day, respectively). The HL diet had reduced digestibility of DM and organic matter (OM) (−3% and −4%, respectively), and also reduced the efficiency of intake N conversion into milk N (−4%). The S chop length increased total tract digestibility of DM and OM (both +4%), regardless of inclusion rate. Inclusion of lucerne silage at 25% of forage DM increased milk yield relative to 75% inclusion, but a S chop length partially mitigated adverse effects of HL on DMI and milk yield in experiment 1 and on DM digestibility in experiment 2.     

Effects of silage digestibility on intake and body reserves of dry cows and performance in the first part of the next lactation

This experiment evaluated different strategies for allocating first-cut grass silages to dry dairy cows that had low body-condition score (BCS) at drying off. A total of 48 moderately yielding Holstein-Friesian cows were used, receiving one of three dietary treatments in the dry period and a single lactation diet based on a flat-rate of concentrates and grass silage ad libitum. Throughout the dry period, one group received a low-digestibility silage (harvested 15 June 1998; LL; metabolisable energy (ME) = 10.3 MJ/kg dry matter (DM)) and a second group received a high-digestibility silage (harvested 9 May 1998, HH; ME = 11.7 MJ/kg DM). A third strategy (LH) offered the low-digestibility silage in the early dry period and the high-digestibility silage in the final 3 weeks before calving. The silages had very different crude protein concentrations (144 and 201 g/kg DM) and intakes were widely divergent (10.1 v. 13.5 kg DM/day) across the dry period. No concentrates were fed during the dry period. Silage quality had a very large effect on liveweight change, with treatment means of 0.32 and 1.75 kg/day for LL and HH, respectively. BCS changes followed a similar pattern, though no cows became over-conditioned and blood metabolites were within normal ranges. Increased silage digestibility in the late dry period led to a substantial increase in milk fat concentration and a smaller increase in milk protein concentration, the latter confined to the first full week of lactation. Depression of milk fat appears related to low blood glucose when dry cows in low body condition are fed at a low level. The LH strategy avoided the tendency for lower milk yields and fat concentration that resulted from feeding the low-digestibility silage until calving. This strategy also avoided the higher calf weights that resulted from feeding the high-digestibility silage in the early dry period.     

Influence of the method of forage conservation on feeding behaviour, intake and characteristics of reticulo-rumen content, in sheep fed ad libitum.

The influence of silage conservation methods on eating behaviour and the characteristics of reticulo-rumen contents was studied in sheep by comparing 3 forages, a silage without additive (WAS), one with additive (FAS) and hay (H), prepared from the same cut green forage. The sheep were rumen fistulated. WAS was very badly and FAS poorly preserved while the hay was dried under favourable conditions. The forages were fed ad libitum and the dry matter (DM) intake was 1,054, 1,241 and 1,469 g/day for WAS, FAS and H respectively. There was a single feeding in the morning. At the main meal, DM intake was 270, 317 and 388 g/day and ingestion rate 4.76, 4.56 and 4.16 g of DM/min for WAS, FAS and H respectively. There was slight recovery in ingestion around 16-19 h with hay and FAS but not with WAS. With hay, rumination lasted much longer than with the silages and began sooner after the end of the main meal. In contrast, overall rumination efficiency was the same for hay and FAS. There were fewer contractions of the reticulo-rumen with both WAS and hay. The amounts of reticulo-rumen contents were comparable for the 2 silages and higher for hay. The amounts of NH3 in the contents were the same with WAS and hay but greater with FAS. With WAS, contents were richer in butyric, valeric and caproic acids. The DM turnover rate of the contents was the same for FAS and hay and lower, but not significantly, for WAS. Accordingly, with silage, satiety seems to be rapidly reached but there was no evidence that organoleptic factors were involved. There were no problems with the digestion rate of silages. However, the factors limiting silage intake persisted throughout the diurnal cycle, and reticulo-rumen fill was affected. The more poorly preserved the silage the more these factors reduced the duration and volume of the meals, or both.     

Feeding dried distillers grains with solubles to lactating beef cows: impact of excess protein and fat on cow performance,milk production and pre-weaning progeny growth

Multiparous Angus×Simmental cows (n=54, 5.22±2.51 years) with male progeny were fed one of two diets supplemented with either dried distillers grains with solubles (DDGS) or soybean meal (CON), from calving until day 129 postpartum (PP) to determine effects of excess protein and fat on cow performance, milk composition and calf growth. Diets were formulated to be isocaloric and consisted of rye hay and DDGS (19.4% CP; 8.76% fat), or corn silage, rye hay and soybean meal (11.7% CP; 2.06% fat). Cow–calf pairs were allotted by cow and calf age, BW and breed. Cow BW and body condition score (BCS; P⩾0.13) were similar throughout the experiment. A weigh-suckle-weigh was performed on day 64 and day 110±10 PP to determine milk production. Milk was collected on day 68 and day 116±10 PP for analysis of milk components. Milk production was unaffected (P⩾0.75) by dietary treatments. Milk urea nitrogen was increased at both time points in DDGS compared with CON cows (P<0.01). Protein was decreased (P=0.01) and fat was increased (P=0.01) in milk from DDGS compared with CON cows on day 68 PP. Compared to CON, DDGS decreased medium chain FA (P<0.01) and increased long chain FA (P<0.01) at both time points. Saturated FA content of milk was decreased (P<0.01) at both time-points in DDGS compared with CON cows, which resulted in an increase (P<0.01) in monounsaturated and polyunsaturated FA, including cis-9, trans-11 conjugated linoleic acid. Daily gain of the DDGS calves was increased (P=0.01) compared with CON calves, resulting in heavier BW on day 129 (P=0.01). Heavier BW of DDGS calves was maintained through weaning (P=0.01). Timed-artificial insemination (TAI) rates were greater for cows fed DDGS compared with cows fed CON (P<0.02), but dietary treatment had no effect on overall pregnancy rates (P=0.64). In summary, feeding DDGS to lactating beef cows did not change cow BW or BCS, but did improve TAI rates and altered milk composition compared with CON. As a result, male progeny from cows fed DDGS during lactation had greater average daily gain and were heavier at day 129 and at weaning compared with male progeny from cows fed a control diet.     

Could a big gut be too costly for muskoxen (Ovibos moschatus) in their first winter?

Young mammalian herbivores are more vulnerable to harsh winter conditions than adults, especially among large circumpolar species like the muskox (Ovibos moschatus). We compared feeding responses of muskox calves (body mass 95 kg) with those of mature, non-reproductive females (body mass 227 kg) in mid-winter when air temperatures fell to -40 degrees C. Food intakes (1.8-2.2 kg digestible dry matter (DM)d(-1)), digesta fill (27-32 kg wet mass) and digestibility of hay (52-58% of DM; 49-55% of gross energy) were similar between age groups even though calves were much smaller than adults. Calves fed more frequently (12 vs. 8 feeding bouts per day) and thus spent more time feeding each day than adults (387 vs. 343 min per day). High mass-specific food intakes of calves indicate higher requirements for maintenance of body tissue than adults, which could be related to a larger intestinal tract in young muskoxen. Notably, cows and calves maintained a constant body mass throughout, indicating that they were feeding at maintenance levels and that the relatively higher intakes of calves were not related to growth. Together, these data suggest that limited food availability due to snow cover or high animal density may reduce the survival of muskoxen in their first winter.     

Influence supplementary feeding on bark browsing by red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) under experimental conditions

The effect of various supplementary feeds on bark browsing was studied in red deer under controlled conditions. Fifteen female red deer were randomly assigned to five dietary treatments (n = 3 animals each): meadow hay as a control (C), combinations of meadow hay with grass silage (GS), maize silage (MS), maize silage with oats (MSO) or a pelleted concentrate (PC). The deer were kept in enclosures where we offered fresh spruce stems daily. The experiment consisted of two periods. In the first period (A), the animals had free access to food during 24 h, while in the second period (B), the access was restricted to night hours only. In both periods, the supplementary feeds were available ad libitum. Mean daily consumption of browsed bark in the control group in period A was 1,053 g while in the remaining groups it ranged from six to 20 g. In period B, simulating the conditions in disturbed hunting areas, bark consumption in all groups increased considerably, the highest increase being found in groups GS (430 vs. 19 g/day) and MS (101 vs. 6 g/day). In period A, the highest dry matter (DM) intake including browse was found in group MS (2,816 g/day) and the lowest one in group GS (2,307 g/day). In period B, the highest (2,763 g/day) and the lowest (2,153 g/day) DM intake was observed in groups PC and MSO, respectively. If red deer is fed supplementary, meadow hay should be combined with maize silage, grass silage or concentrate to reduce bark browsing in forests. The bark browsing rate may increase considerably if red deer are disturbed or their grazing cycle is impaired.     

Effect of grain and forage fractions of corn silage on milk production and composition in dairy cows

Corn silage (CS) is associated with a reduction in milk fat content. The fact that CS is constituted of a grain and a forage fraction could explain this effect. This experiment evaluated the effect of grain fraction of CS on rumen fermentation, production performance and milk composition. Earless CS (ECS) was harvested after manually removing corn ears from the plant. Whole CS (WCS) was harvested from the same field on the same day. Eight (four ruminally fistulated) multiparous Holstein cows (84 days in milk) were utilized in a double 4 × 4 Latin square with 21-day periods. Treatments were (dry matter (DM) basis) (1) 23.0% WCS; (2) 12.4% ECS plus 10.6% high moisture corn (HMC) to obtain reconstituted CS (RCS); (3) 23.0% ECS; and (4) 23.0% timothy silage (TS). Diets were formulated to be isonitrogenous and were fed as total mixed ration once a day. DM intake (DMI), milk yield, 4.0% fat-corrected milk (FCM), as well as protein concentration and yield were higher for WCS than ECS. Compared with WCS, cows tended to eat less with RCS, and produced less milk and milk protein. However, yield of FCM was similar between WCS and RCS. Milk fat concentration and yield, as well as the specific ratio of t11 18:1 to t10 18:1 in milk fat did not differ among diets. Milk urea-N tended to be higher for ECS than WCS and TS, whereas ruminal NH₃-N was higher with ECS than TS. Rumen pH decreased linearly with time after feeding but was not different between treatments. Higher acetate and lower propionate concentration resulted in greater acetate to propionate ratio with ECS compared with WCS. In conclusion, removing grain fraction from CS decreased milk production and modified rumen fermentation without affecting milk fat concentration and yield. Moreover, despite some differences in DMI and total ruminal volatile fatty acid concentration between WCS and RCS, the restoration of FCM yield, using HMC in RCS diets, to a level of production similar to WCS highlights the importance of energy and nutrients supplied by the grain fraction of CS to support milk yield.     

Effects of pressed beet pulp silage inclusion in maize-based rations on performance of high-yielding dairy cows and parameters of rumen fermentation

Beet pulp contains high amounts of pectins that can reduce the risk of rumen disorders compared to using feedstuffs high in starch. The objective was to study the effects of inclusion of ensiled pressed beet pulp in total mixed rations (TMR) for high-yielding dairy cows. Two TMR containing no or about 20% (on dry matter (DM) basis) beet pulp silage were used. The beet pulp silage mainly replaced maize silage and corn cob silage. The TMR were intentionally equal in the concentrations of energy and utilisable crude protein (CP) at the duodenum. TMR were fed to 39 and 40 dairy cows, respectively, for 118 days. The average daily milk yield was about 43 kg/day. No significant differences in milk yield and milk fat or milk protein content were detected. DM intake of cows was significantly reduced by the inclusion of beet pulp silage (23.0 v. 24.5 kg/day). However, a digestibility study, separately conducted with sheep, showed a significantly higher organic matter digestibility and metabolisable energy concentration for the TMR that contained beet pulp silage. In vitro gas production kinetics indicated that the intensity of fermentation was lower in the TMR that contained beet pulp silage. In vitro production of short-chain fatty acids, studied using a Rusitec, did not differ between the TMR. However, the inclusion of beet pulp silage in the ration caused a significant reduction in the efficiency of microbial CP synthesis in vitro. The amino acid profile of microbial protein remained unchanged. It was concluded that beet pulp silage has specific effects on ruminal fermentation that may depress feed intake of cows but improve digestibility. An inclusion of beet pulp silage of up to 20% of DM in rations for high-yielding dairy cows is possible without significant effects on milk yield and milk protein or milk fat.     

Effects of mixtures of red clover and maize silages on the partitioning of dietary nitrogen between milk and urine by dairy cows

Eight multiparous lactating Holstein-Friesian cows were used to evaluate the partitioning of dietary nitrogen (N) from diets based on mixtures of red clover and maize silages in comparison with diets based on ryegrass silage. All cows received 4 kg/day of a standard dairy concentrate with one of four forage treatments in an incomplete changeover design with three 4-week periods. Three treatments were based on mixtures of red clover and maize silage. N intake was altered both by varying the ratio of these silages (40/60 and 25/75 on a dry matter (DM) basis) and by an additional treatment for which the DM intake of the 40/60 mixture was restricted to the level achieved with grass silage. Rumen passage rates were estimated from faecal excretion curves following a pulse oral dose of Dysprosium-labeled silage and urinary excretion of purine derivatives (PD) was used as an index of rumen microbial protein synthesis. Red clover silage mixtures led to significantly increased feed intake (21.5, 20.7 and 15.2 kg DM/day for 40/60 and 25/75 red clover/maize silage mixtures and grass silage, respectively), milk production (25.8, 27.8 and 20.0 kg/day for the same treatments, respectively) and milk component yields, but were without effect on milk fat and protein concentrations. The large increase in the yield of milk (24.5 kg/day) and milk components for the restricted red clover/maize silage treatment, in comparison with the grass silage treatment, was proportionately greater than the increase in DM intake (16.6 kg DM/day). There were no significant treatment effects on diet digestibility, while the higher intakes of red clover silage mixtures were associated with higher rumen passage rates (5.82%, 6.24% and 4.55%/h, respectively). There were significant effects of both N intake and forage source on the partitioning of dietary N between milk and urine. When dietary protein was diluted by the inclusion of maize silage, red clover silage led to increased milk N and reduced urinary N in comparison with grass silage. Improvements in N utilisation may be related to increased dietary starch and/or rumen passage rates leading to increased microbial protein synthesis for these treatments. Urinary excretion of PD was significantly higher for all diets based on mixtures of red clover and maize silages, in comparison with grass silage. Urinary N output was close to literature predictions based on N intake for the diet based on ryegrass silage, but 40 to 80 g/day (25% to 30%) less than predicted for the diets based on the mixtures of red clover and maize silages.     

Herbage utilisation method affects rumen fluid and milk fatty acid profile in Holstein and Montbéliarde cows

Compared with maize silage- and concentrate-based diets, herbage-based diets were repeatedly shown to favourably influence the milk fatty acid (FA) profile. However, it is unclear how the herbage feeding mode (grazing vs indoor green-feeding) and conservation (fresh herbage vs hay vs silage) modify the milk FA profile. Therefore, the aim of the present experiment was to investigate the effect of different herbage utilisation methods (including herbage feeding mode and herbage conservation method) on the ruminal biohydrogenation of dietary FA and the consequences on the milk FA composition in cows of two breeds (Holstein and Montbéliarde). Concomitant effects of botanical composition and phenological stage of the herbage on milk FA profile were controlled for by harvesting barn-dried hay and silage simultaneously as first cut from the same ryegrass-dominated grassland in a semi-mountainous region. Seven weeks later, the first regrowth of the same plot was used as fresh herbage, either grazed or fed indoor (indoor green-feeding). Twenty-four Montbéliarde and 24 Holstein cows were randomly allocated to four groups of 12 cows balanced by breed, parity, and milk yield. In a free-stall barn, three groups were given ad libitum access to hay, silage, or fresh herbage, respectively. The fourth group was strip-grazing. All cows were supplemented with 3 kg DM/day of the same energy-rich concentrate. After 2 weeks of adaptation to the forage, samples of forage, concentrate, milk, blood, and rumen fluid were collected. Fatty acid composition of forages, rumen fluid, and milk was analysed by gas chromatography. Haymaking reduced total FA content of the herbage, in particular that of linoleic acid (LA) and α-linolenic acid (ALA). Still, rumen fluid lipids of hay-fed cows had the highest proportion of rumenic acid, LA, ALA, and total polyunsaturated fatty acids (PUFAs). Milk fat from hay-fed cows had the highest proportion of LA, and the apparent transfer rates from feed to milk of LA and ALA were higher in hay-fed cows than in silage-fed cows. The proportion of PUFAs was highest in milk fat from grazing and indoor green-fed Montbéliarde cows and lowest in silage-fed cows of both breeds. In conclusion, the herbage utilisation method affects the ruminal biohydrogenation of LA and ALA, whereby herbage drying particularly increases their transfer from herbage to milk.     

Influence of hay particle size at different concentrate and feeding levels on digestive processes and feed intake in ruminants. 2. passage,digestibility and feed intake

In order to study the main effects of particle size, three ruminally fistulated cows (550 to 580 kg BW) were fed a constant low concentrate level (3.56 kg DM/d, 20% of total DMI) and a fibre‐rich hay (approximately 60% NDF in DM) in long (28.7 mm), chopped (9.2 mm) and fine ground (2.9 mm) form in a 3 x 3 Latin square design. In another three factorial experiment with 8 wethers (4 animals were ruminally fistulated, mean BW = 68 kg) the main effects and interactions of the above mentioned hay particle sizes at two concentrate levels (10.4 to 13.3% and 29.5 to 40.1% of DMI, resp.) and two intake levels (restricted and ad libitum) were investigated. In comparison to long hay (28.7 mm), feeding of chopped hay (9.2 mm) at low concentrate levels, increased not only the hay intake (7% in dairy cows and 13% in sheep) but also the intake of digestible organic matter (12% in dairy cows and 32% in sheep), due to an increase in the apparent digestibility of OM by 3.8% in dairy cows and 8.2% in sheep. Ad libitum feeding of fine ground hay in combination with low concentrate amount in the ration increased the passage rate in the hindgut and consequently the hay intake, but not the intake of DOM, due to a significant depression of digestibility, especially of fibre fractions (4 to 7% in dairy cows and 4.5 to 14% in sheep), in comparison to 28.7 and 9.2 mm hay particle sizes. The digestibility decreased significantly with restricted feeding of fine ground hay in sheep only in comparison to 9.2 mm particle size. A threefold increase of concentrate amount levelled out all effects of the particle size reduction. The effect of particle size was more pronounced in sheep than in dairy cows.     

Effects of ensiled forage legumes on performance of store finishing lambs

Male Beulah speckled face lambs (initial live weight (LW) 28.8 ± 0.31 kg) were allocated to three dietary treatments to evaluate the performance of store lambs of a hill breed when offered ensiled lucerne (Medicago sativa), red clover (Trifolium pratense) or ryegrass. Second-cut silage bales (wilted and inoculated) were prepared from 3-year old lucerne and red clover stands and a 1-year old ryegrass sward. All the lambs were group-housed and offered ad libitum ryegrass silage during a 3-week co-variate period. This was followed by a week of dietary changeover period, after which the lambs were housed individually and offered their treatment diet ad libitum. All the lambs received a flat rate supplement of pelleted molassed sugarbeet (250 g fresh weight/day). Individual intakes were determined daily, and weekly measurements of LW and body condition score (CS) were made. Additional measurements were taken by scanning the lambs for depth of Longissimus dorsi (LD) muscle and subcutaneous fat. Over an experimental period of 7 weeks, the lambs offered red clover silage had a higher voluntary silage dry matter (DM) intake, total DM intake and metabolisable energy (ME) intake (P < 0.001) than lambs offered either lucerne or ryegrass silage. This resulted in a faster (P < 0.001) growth rate and increase (P < 0.001) in CS, with no difference between lucerne and ryegrass silages. The feed conversion efficiency (FCE) was 8.0 ± 0.61 kg feed/kg gain for lambs fed red clover silage, compared with 16.6 ± 2.82 and 10.6 ± 1.94 kg feed/kg gain for lucerne and ryegrass silage, respectively. The CP intake was higher (P < 0.001) for lambs fed the lucerne and red clover silages than for the ryegrass silage treatment. The concentration of plasma total protein (TP) was higher (P < 0.05) for lambs offered ryegrass silage versus lucerne and red clover silage. Urea concentrations were highest for lambs fed lucerne silage and lowest for those fed ryegrass silage (P < 0.05). The glucose concentration was higher (P < 0.05) for lambs offered red clover silage, whereas non-esterified fatty acids (NEFA) concentration was higher (P < 0.05) for lambs offered lucerne silage. Substituting ryegrass silage with red clover silage has the potential to improve the performance of finishing store lambs.     

The effect of forage supplementation on the behaviour of grazing dairy cows

In a series of three experiments, the effect of offering conserved forage indoors to grazing dairy cows was examined. In Experiment 1, hay was offered ad libitum for 45 min after morning milking. In Experiments 2 (early season) and 3 (late season), silage was offered ad libitum either after morning milking or overnight. All experiments included a control grazing treatment that received no supplementary forage. Grazing time was reduced by offering forage, particularly at the high levels of forage intake when cows were housed overnight. The bite size and rate of herbage DM intake were reduced for cows eating large quantities of silage, but the rate of biting was not affected. As the grazing season advanced there was a small increase in the rate of biting and grazing time in all treatments, but a large reduction in bite size and the rate of herbage intake. Heifers had a 25% smaller bite size, 5% faster rate of biting and similar grazing times to cows. Spring-calving cows had higher grazing times than autumn-calving cows, with little difference in biting rate. Forage was consumed at a rate between 2 and 4 times that of grazed herbage. Offering forage increased rumination times, particularly when it was eaten in large quantities. Rumination time was reduced for cows on spring grass and when total intakes were low.