The effects of high-sugar ryegrass/red clover silage diets on intake, production, digestibility, and N utilization in dairy cows, as measured in vivo and predicted by the NorFor model.

Grass silage-based diets often result in poor nitrogen utilization when fed to dairy cows. Perennial ryegrass cultivars with high concentrations of water-soluble carbohydrates (WSC) have proven potential for correcting this imbalance when fed fresh, and have also been shown to increase feed intake, milk production, and N utilization. The possibility of achieving corresponding effects with silage-based diets was investigated in change-over experiments in an incomplete block design with 16 (yr 1) or 12 (yr 2) Swedish Red dairy cows in mid lactation. Measurements on N excretion and rumen parameters were performed on subgroups of 8 and 4 cows, respectively. In yr 1, 2 ryegrass cultivars (standard = Fennema; high-WSC = Aberdart) and 2 cuts (first and second) were compared. In all treatments, ryegrass silage was mixed 75/25 on a dry matter (DM) basis, with red clover silage before feeding out. In yr 2, 1 basic mixture from the different cuts of these 2 cultivars was used and experimental factors were red clover silage inclusion (25 or 50%) and sucrose addition (0 or 10%) on a silage DM basis. Differences in WSC concentration in the silage mixtures in yr 1 were minor, whereas the differences between cuts were more substantial: 100 compared with 111 g/kg of DM for first-cut silage and 39 compared with 47 g/kg of DM for second-cut silage. The silages fed in yr 2 had a WSC concentration of 115 or 102 g/kg of DM (25 or 50% red clover, respectively), but when sucrose was added WSC concentration reached 198 and 189 g/kg of DM, respectively. Milk production (kg/d) did not differ between treatments in either year. Red clover inclusion to 50% of silage DM increased milk protein. Nitrogen efficiency (milk N/feed N) increased from 0.231 to 0.254 with sucrose inclusion in yr 2 (average for the 2 red clover levels). Overall rumen pH was 5.99 and increased sucrose level did not affect pH level or daily pH pattern. Sucrose addition reduced neutral detergent fiber digestibility, particularly at higher inclusion rates of clover. Rumen pool of total purines did not differ between treatments, nor did protein production assessed from urinary allantoin. The NorFor feed evaluation model overestimated digestibility of neutral detergent fiber and N, but underestimated N excretion in feces. We concluded that addition of WSC to dairy cow diets at levels up to 3 kg of WSC per day (>14% of DM) does not dramatically affect cow performance.

Invited review: Carryover effects of early lactation feeding on total lactation performance in dairy cows.

In comparison with the intensive research on the direct effects of energy supply on dairy cow lactation performance, little attention has been paid to the effect of early lactation feeding on subsequent production. The present paper reviews 9 studies carried out with the aim of quantifying the immediate and subsequent responses in milk production and body weight to early lactation feeding. Most results showed that a more generous feeding in early lactation caused a positive carryover effect on subsequent production, whereas an inadequate level of feed in early lactation has been shown to reduce subsequent milk yield. The carryover periods ranged from 3 to 12 wk and the difference in milk yield between cows in the carryover periods ranged between 1.5 and 4.5kg of milk/cow per day. When calculated as a percentage of the immediate effect, the carryover effect ranged from 22 to 63%. In 2 of the 9 papers reviewed, the authors found no carryover effect, probably due to the long post-treatment periods in these studies. This is supported by the other studies in which the carryover effect was only significant in a limited period after end of treatment. The magnitude of the carryover effect seems to be determined by several factors including duration of the treatment and post-treatment feeding level. The most important factor though appears to be the magnitude of over- or underfeeding (i.e., a strong relationship between the treatment period feeding level and the subsequent response in production).

High- and low-purity glycerine supplementation to dairy cows in early lactation: effects on silage intake, milk production and metabolism.

This study evaluated the effects of supplemental low- and high-purity glycerine on silage intake, milk yield and composition, plasma metabolites and body condition score (BCS) in dairy cows. A total of 42 cows of the Swedish Red Breed, housed in individual tie stalls, were fed 0.25 kg of low- or high-purity glycerine on top of concentrate, twice daily, during the first 4 weeks of lactation. One-third of the cows acted as controls, receiving no glycerine. Silage was fed for ad libitum intake and concentrate was fed at restricted level of intake, about 6 kg/day for primiparous cows and 7 kg/day for multiparous cows. Feed refusals were weighed daily. Cows were milked twice daily, milk yield was recorded on four occasions per week and milk samples were collected simultaneously. Blood samples were drawn from the coccygeal vessel once a week. Low- and high-purity glycerine had no effect on silage or total dry matter intake (P = 0.38 and P = 0.75, respectively) or on BCS (P = 0.45). Cows fed high-purity glycerine tended to have higher milk yield than control cows (P = 0.06). Milk composition tended to differ among treatments. No main effects of treatment on concentration of glycerine (P = 0.44), glucose (P = 0.78), insulin (P = 0.33), non-esterified fatty acids (P = 0.33) and ß-hydroxybutyrate (P = 0.15) in plasma. These data indicate that high-purity glycerine has the potential to increase milk yield, as well as enhance the milk protein concentration and milk fat + protein yield.

Effect of dietary proportion of grass silage on milk fat with emphasis on odd- and branched-chain fatty acids in dairy cows.

High proportions of forage in diets fed to dairy cows are interesting options in conventional production, and mandatory in organic dairy farming (e.g., within the European Union). The objectives of the present study were to study the milk fatty acid (FA) profiles, with particular focus on the odd- and branched-chain FA (OBCFA) and their association with diet composition, using 3 different proportions of grass silage in the diet. The OBCFA profiles in milk have been suggested to be potential markers to assess nutrient supply to the cows. The study included data from 24 cows in 2008 and 26 cows in 2009, using pooled milk samples from morning and evening milking within 24 h. The 3 diets were composed of the same feeds: grass silage and grain-based concentrate, but the silage component was fed in different proportions, namely 50, 70, and 85% of total dry matter intake. The cows were in late lactation, with a mean of 220 (SD=15) days in milk in 2008, and 216 (SD=35) days in milk in 2009, at the onset of the trial. Increased proportions of grass silage in the diet increased the intake of C18:3n-3, and decreased the intake of C18:2n-6 and intake of total FA. The daily intake of C18:3n-3 and C18:2n-6 was reflected in a similar increase in milk C18:3n-3, whereas the concentration of milk C18:2n-6 decreased with increasing proportion of grass silage in the diet. Increased proportions of grass silage in the diet increased the concentration of conjugated linoleic acid and the linear odd-chain FA C15:0 and C17:0, the branched-chain iso C15:0 and total OBCFA in milk. The concentration of total OBCFA in milk was shown to be positively correlated with dietary content of neutral detergent fiber. This suggests that the concentration of milk OBCFA may be useful in the future to indicate low forage intake in cows under conditions when it is not possible to measure individual forage intake.

Methanogenic population and CH4 production in swedish dairy cows fed different levels of forage.

Methanogenic community structure, methane production (CH(4)), and volatile fatty acid (VFA) profiles were investigated in Swedish dairy cows fed a diet with a forage/concentrate ratio of 500/500 or 900/100 g/kg of dry matter (DM) of total DM intake (DMI). The rumen methanogenic population was evaluated using terminal restriction fragment length polymorphism (T-RFLP) analysis, 16S rRNA gene libraries, and quantitative real-time PCR (qRT-PCR). Mean CH(4) yields did not differ (P > 0.05) between diets, being 16.9 and 20.2 g/kg DMI for the 500/500 and 900/100 diets, respectively. The T-RFLP analysis revealed that populations differed between individual cows and that each individual population responded differently to the diets. The 16S rRNA gene libraries revealed that Methanobrevibacter spp. dominated for both diets. CH(4) production was positively correlated with a dominance of sequences representing T-RFs related to Methanobrevibacter thaueri, Methanobrevibacter millerae, and Methanobrevibacter smithii relative to Methanobrevibacter ruminantium and Methanobrevibacter olleyae. Total numbers of methanogens and total numbers of Methanobacteriales were significantly higher with the 500/500 diet (P < 0.0004 and P < 0.002, respectively). However, no relationship was found between CH(4) production and total number of methanogens. No differences were seen in total VFA, propionic acid, or acetic acid contents, but the molar proportion of butyric acid in the rumen was higher for the 500/500 diet than for the 900/100 diet (P < 0.05). Interestingly, the results also revealed that a division of the identified methanogenic species into two groups, suggested in the work of King et al. (E. E. King, R. P. Smith, B. St-Pierre, and A. D. G. Wright, Appl. Environ. Microbiol. 77:5682-5687, 2011), increased the understanding of the variation in CH(4) production between different cows.

Intake and digestion of whole-crop barley and wheat silages by dairy heifers.

The effect of maturity at harvest on the digestibility and intake of large bale silage made from whole-crop barley and wheat when fed to growing heifers was evaluated. Two crops of spring barley (Hordeum distichum cv. Filippa and Kinnan) and 1 of winter wheat (Triticum aestivum cv. Olevin) were harvested at the heading, milk, and dough stages of maturity. The silage was fed to 36 dairy heifers in a balanced crossover experiment with 3 periods and 9 treatments (diets based on 3 crops and 3 stages of maturity), organized into 6 pairs of 3 × 3 Latin squares. No clear relationship was observed between intake and stage of maturity of whole-crop cereal silage, but intake was positively correlated to silage DM content (P < 0.001, r = 0.46) and negatively correlated to NDF content (P < 0.001, r = -0.42). Organic matter digestibility decreased between the heading and milk stages of maturity in all crops (P < 0.001), did not differ between the milk and the dough stages in the 2 barley crops, but increased in the wheat silage (P = 0.034). The NDF digestibility decreased between the heading and milk stages in all crops (P < 0.001), whereas it decreased in 1 barley crop (P < 0.001), increased in the other barley (P = 0.025), and was unchanged in the wheat between the milk and dough stages of maturity. Starch digestibility was less in the 2 barley crops compared with the wheat at the dough stage of maturity (P < 0.001). The feeding value of the whole-crop barley and wheat declined between the heading and milk stages of maturity, but thereafter the effect of maturity on the feeding value was minor.

Digestibility of whole-crop barley and oat silages in dairy heifers.

This study evaluated the digestibility of whole-crop cereal silage (WCCS) made from oats and six-rowed barley harvested at the heading, early milk and early dough stages, and two-rowed barley harvested at the early milk and early dough stages of maturity. The eight WCCSs were fed to 32 Swedish Red heifers in a changeover design over three periods of 28 days each. The heifers were first fed ad libitum for 17 days and then at 0.95 of ad libitum for 11 days of each period. During the last 5 days all faeces and orts were collected to determine the digestibility of the silages. Only the maturity stage effect was significant for the WCCS organic matter (OM) digestibility and the average OM digestibility was higher at the heading stage (698 g/kg) than at early milk (647 g/kg) and early dough (652 g/kg) stages of maturity. For neutral detergent fibre (NDF) digestibility the crop × maturity stage effect was significant. The NDF digestibility decreased from the heading to the early milk stage for both six-rowed barley (746 to 607 g/kg) and oats (698 to 596 g/kg). There was no further significant decrease in NDF digestibility for six-rowed barley at the early dough stage (577 g/kg), but for two-rowed barley it decreased from the early milk (682 g/kg) to the early dough (573 g/kg) stage, and also for oats the NDF digestibility was lowest at the early dough stage (507 g/kg). The decrease in NDF digestibility during maturation was to a large extent compensated by an increase in starch concentration in the crops. The starch digestibility was lower for six-rowed barley at early dough stage (948 g/kg) than at early milk stage (977 g/kg), and was also lower compared with oats (979 g/kg) at early dough stage. The average crude protein (CP) digestibility was higher at the heading (646 g/kg) and the early milk (642 g/kg) stages than at the early dough stage (599 g/kg), and oats had higher average CP digestibility (650 g/kg) than six-rowed (613 g/kg) and two-rowed (624 g/kg) barley. Delaying the harvest of WCCS from the heading to the early milk and dough stage of maturity will decrease the OM digestibility; as a result there is a decreased NDF digestibility.

Effect of feeding cassava and/or Stylosanthes foliage on the performance of crossbred growing cattle.

The effect of feeding different levels of cassava foliage (Manihot esculenta, Crantz) and/or Stylosanthes guianensis foliage on the growth and digestibility was studied using twenty eight 6-month-old crossbred growing cattle (50% local Yellow cattle and 50% Sindhi) (both Bos indicus) weighing on average 114 kg at start. All animals were fed a basal diet consisting of urea treated rice straw (URTRS) fed ad libitum, 0.87 kg concentrate and 0.22 kg molasses on dry matter (DM) basis. The treatments were four supplements: soybean meal, cassava foliage, stylosanthes foliage or a mix of stylosanthes foliage and cassava foliage all giving the same nitrogen intake. The consumption of tannins and hydrogen cyanide (HCN) were significantly higher in groups fed a mixture of foliages compared with only cassava foliage, respectively. There were 30% and 19%, respectively, higher live weight gain in the group fed a mixture of foliages as compared to the groups fed only cassava or stylosanthes. The factors of low organic matter and high level of HCN in the diet when feeding only cassava foliage might explain the negative effects on intake, neutral detergent fibre digestibility and nitrogen retention, and resulted in lower growth rates.

Effects on the equine colon ecosystem of grass silage and haylage diets after an abrupt change from hay.

The objective of this study was to investigate the effect of an abrupt change from grass hay (81% DM) to grass silage (36% DM) or grass haylage (55% DM), fed at similar DM intakes, and to compare the effects of silage and haylage on the composition and activities of the colon microflora. The forages were from the same swath harvested on the same day. Four adult colon-fistulated geldings were randomly assigned to diets in a crossover design. The study started with a preperiod when all 4 horses received the hay diet, followed by an abrupt feed change to the haylage diet for 2 horses and the silage diet for 2 horses. All 4 horses then had a new second preperiod of hay, followed by an abrupt feed change to the opposite haylage and silage diet. The periods were 21 d long, and the forage-only diets were supplemented with minerals and salt. The abrupt feed changes were made at 0800 h. Colon samples were taken before the abrupt feed change, 4 and 28 h after the feed change, and 8, 15, and 21 d after the feed change, all at 1200 h. Colon bacterial counts, VFA, pH, and DM concentrations were unchanged throughout the first 28 h after the abrupt feed change from hay to haylage and silage. Also, fecal pH and DM concentrations were unchanged during the first 28 h. During the weekly observations, colon lactobacilli counts increased (P = 0.023) in horses receiving the silage diet and were greater than on the haylage diet at 21 d. Streptococci counts decreased (P = 0.046) in horses receiving the haylage diet and were less than on the silage diet at 15 and 21 d. Total VFA concentrations and colon and fecal pH did not differ between diets and were unchanged throughout the weekly observations. The DM concentration of colon digesta and feces decreased (P = 0.030 and 0.049, respectively) on both diets during the weekly observations. The results suggest that in horses fed at the maintenance level of energy intake, an abrupt feed change from grass hay to grass silage or grass haylage from the same crop does not induce any major alterations in the colon ecosystem during the first 28 h. During the subsequent 3-wk period, colon and fecal DM decreased and there were alterations in the lactobacilli and streptococci bacterial counts. The changes in lactobacilli and streptococci counts need further investigation.

Effects of crude protein intake from grass silage-only diets on the equine colon ecosystem after an abrupt feed change.

The objective of this study was to investigate the effect of CP intake from 2 grass silage-only diets, differing in CP concentration, fed at similar DMI on the equine colon ecosystem after an abrupt feed change between the diets. Four adult right ventral colon-fistulated geldings were fed one silage-only diet high in CP (HP, 873 g of CP/d) and one diet providing recommended intakes (RP, 615 g of CP/d). An adaptation period of 15 d on either the HP or the RP diet was followed by 2 experimental periods when the diets were fed for 22 d each in a crossover design. Colon samples were taken before and at 4, 12, and 24 h, and at 7, 14, and 22 d after the feed change. During the first 24 h after the abrupt feed change, the concentrations of total anaerobic bacteria and lactobacilli were greater on the HP than the RP diet (7.1 vs. 6.7 log(10) cfu/mL, P = 0.021, 6.0 vs. 5.5 log(10) cfu/mL, P = 0.021, respectively). During the first 24 h post feed change, VFA concentrations did not differ between the diets. From 7 to 22 d, total VFA concentrations were greater on the HP diet than on the RP diet (51.8 vs. 45.1 mmol/L, P = 0.034), and colon pH was lower on the HP diet than on the RP diet (6.9 vs. 7.2, P = 0.035). After an adaptation period of 22 d, N, ammonia, and urea concentrations and osmolality of the colon fluid did not differ between diets. Fecal pH and colon and fecal DM were unchanged throughout the experiment. The results suggest that, in horses fed at the maintenance level of energy intake, a feed change between silages with different CP content may alter the colon bacterial counts within the first 24 h. Moreover, during the subsequent 3 wk, pH decreased slightly and VFA concentrations increased, but no other major alterations occurred in the composition and activities of the colon ecosystem or fecal DM.

Bacillus cereus spores in raw milk: factors affecting the contamination of milk during the grazing period.

Psychrotrophic Bacillus cereus is a limiting factor for the shelf-life of pasteurized milk, particularly during the grazing season. Potential sources of contamination and factors that might affect the spore content of milk were studied in detail for a group of eight cows during three 2-wk study periods from June to September over 2 yr. The spore content of milk was strongly associated with the degree of contamination of the teats with soil. High water content of soil, low evaporation of water and dirty access alloys were the most important factors correlating with high spore concentrations. The spore content of soil varied from < 50 to 380,000/g, depending on time and sampling site. The milking equipment did not contribute significantly to the contamination. The spore contents in air during milking (< 100 cfu/m3) and in feed (silage, hay, fresh grass, and concentrates) were too low to be of importance for contamination. The spore content in dung was also low. Further support that soil was the major contamination source was found by comparison of genetic fingerprints by random amplified polymorphic DNA polymerase chain reaction of isolates of B. cereus from soil and milk and by teat cleansing experiments, which resulted in reduced contamination levels in milk.

Uterine bacteriology, histology, resumption of ovarian activity and granulocyte function of the postpartum cow in different milking frequencies.

The postpartum uterine bacteriology, histology, resumption of ovarian activity and polymorphonuclear granulocyte (PMN) number and function in 18 Swedish dairy cows were studied. Cows were milked either 2x (n = 9) or 3x per day (n = 9). Endometrial biopsy samples for bacteriological and histological investigations were collected during 8 weeks postpartum, starting within one week after calving. Milk samples for progesterone determination were collected twice a week until the cows had shown normal reproductive cyclicity. Blood samples for granulocyte function (phagocytic capacity and total number) were collected from each animal on the same days as when the biopsies were obtained. All animals in both groups were free from bacteria at the latest after 6 weeks post-partum and there was no difference regarding bacterial elimination and bacterial species between milking groups. No difference regarding uterine histology between milking groups was seen. In both groups, 8 cows had normal to slight infiltration of leukocytes in the endometrium at the end of sample collection. No changes in granulocyte function could be seen in the 2 milking groups. Resumption of ovarian activity was detected on day 45.6 +/- 9.3 (mean +/- SD) postpartum in the 2x milking group and 36.6 +/- 9.0 (mean +/- SD) post-partum in the 3x milking group (p = 0.05). Based on our findings, an increased milking frequency from 2 to 3 times a day did not influence the uterine function postpartum.

Fertility in dairy cows managed for calving intervals of 12, 15 or 18 months.

Effects on reproduction in a total of 135 dairy cows managed for calving intervals of 12, 15 or 18 months (72, 38 and 25 cows respectively) were studied. The cows were of the Swedish Red and White Breed (SRB) and the Swedish Freisian Breed (SLB) and were housed in 2 different herds with 3 different management systems (tied, loose, and tied but milked in a milking parlour; mixed). The cows in one of the herds (48 cows) were assigned for milking either 2 times or 3 times a day. When comparing conception rate at 1st insemination (AI) and the percentage of cows finally pregnant, we found no significant differences between the 3 calving interval groups, however, a tendency for a higher conception rate with a 15 months' interval compared with a 12 months' interval was found in one of the herds (50% vs 41.5%). The percentage of finally pregnant animals varied between 81% and 100%, but this variation was mainly attributed to the herd rather than calving interval group. A significantly higher percentage of cows was treated for anoestrous in the 12-month group than in the 15-month group in one of the herds (28.6% vs. 5.3%). The frequency of ovulations with external heat signs increased with ovulation number up to the 4th ovulation and thereafter remained stable. No significant difference was found in number of AIs required per conception with respect to calving intervals, breeds, or milking frequency groups. However, cows milked 3 times a day had a significantly longer interval from the 1st AI to conception compared with cows milked 2 times a day (45.8 days vs 17.6 days, p < .01). Cows kept loose exhibited 1st ovulatory oestrous, approximately 2 weeks earlier (55.9 days vs 69.7 days, p < .05) than their herd mates kept tied. In conclusion, our study shows that lengthening the calving interval to 15 or 18 months may have a positive influence on reproduction in terms of less need for treatments of ovarian disorders and higher conception rates. Our results also indicate that milking 3 times a day may have negative effects, and keeping cows in a loose-housing management system may have positive effects on ovarian function.

Feeding green-cut forage contaminated by radioactive fallout to dairy cows.

Grass contaminated by radioactive fallout from the Chernobyl accident was cut with 150 mm (Treatment 1) and 50 mm (Treatment 2) stubble height and fed to 20 dairy cows. The transfer of 137Cs and 131I from the greencut forage to milk was studied during a four-week and a two-week period, respectively. The four-week period was followed by a three-week period with nearly uncontaminated feeds. Cutting with high stubble height significantly reduced the activity concentration in forage compared with low stubble cutting, the average contents kg-1 dry matter being 385 Bq 137Cs and 24 Bq 131I in Treatment 1 versus 6656 Bq 137Cs and 249 Bq 131I in Treatment 2. Apparent treatment effects were also demonstrated by the 137Cs concentration in milk, with maximum weekly means of 23 Bq kg-1 (Treatment 1) and 92 Bq kg-1 (Treatment 2). Single day maximum concentrations of 131I in milk were 4 Bq kg-1 (Treatment 1) and 9 Bq kg-1 (Treatment 2). The mean transfer coefficients (d kg-1) were calculated to be 0.67 X 10(-2) and 0.19 X 10(-2) for 137Cs (weeks 2-4) and 1.8 X 10(-2) and 0.2 X 10(-2) for 131I (week 2) in Treatments 1 and 2, respectively. The lower value for 137Cs might possibly be associated with an enhanced ash content of the forage. Feeding nearly uncontaminated rations rapidly decreased the 137Cs levels in milk in both treatments with calculated effective half-times over the three-week period of 10 and 7 d, respectively.