Restricting access time at pasture and time of grazing allocation for Holstein dairy cows: Ingestive behaviour,dry matter intake and milk production

The objective of this study was to assess the effects of restricting access time to pasture and time of grazing allocation on grazing behaviour, daily dry matter intake (DMI), rumen fermentation, milk production and composition in dairy cows. Twenty-one autumn-calving Holstein cows were assigned to one of the following 3 treatments: providing access to a daily strip of pasture for either 8 h between 07:00 and 15:00 h (T7–15), 4 h between 07:00 and 11:00 h (T7–11), or 4 h between 11:00 and 15:00 h (T11–15). The experimental period consisted of 3 weeks of adaptation and 6 weeks of measurements. Cows were offered a daily herbage allowance of 18 kg DM/cow to ground level, 6.1 kg DM/day of a ground sorghum grain-based supplement and 5.2 kg DM/day of maize silage. Milk yield was greater for cows with 8 h access time to the pasture (25.4 vs. 24.1 for 8 and 4 h access time, respectively). Milk yield was not different between cows that access early (T7–11) or late (T11–15) to the grazing session. Milk protein yield was greater for cows with 8 h access time (0.75 kg/d) vs. 4 h access time treatments (0.72 kg/d). Cows with late access time to grazing in the morning produce more protein (0.74 kg/d) than cows with early access to the pasture (0.70 kg/d). Duration of access had a significant effect on herbage DMI (8.3 vs. 6.6 kg/d, for 8 and 4 h access, respectively), but there was no significant effect of time of grazing allocation. Intakes of concentrate and maize silage DM did not differ between treatments.     

Dietary grain source and oil supplement: Feeding behavior and lactational performance of Holstein cows

Effects of grain source and dietary oil supplement on dry matter intake (DMI), feeding, chewing behavior, and production performance of lactating dairy cows were evaluated using eight multiparous Holstein cows (77±22.1 days in milk; mean±SD) in a duplicated 4×4 Latin square design with a 2×2 factorial arrangement of treatments. Experimental diets contained either ground barley or ground corn supplemented with either fish oil or soybean oil at 2% of dietary dry matter (DM). Geometric mean particle size of dietary treatments was 4.1 mm. Dry matter intake tended (P=0.09) to be greater for barley- vs. corn-based diets (23.2 vs. 22.3 kg/d), but was reduced for the fish oil compared to soybean oil supplemented diets (21.1 vs. 24.3 kg/d; P<0.001). This reduction in DMI was attributed to smaller meal size (1.24 vs. 1.55 kg of DM; P=0.004) and slower eating rate (0.082 vs. 0.098 kg of DM/min; P<0.001) for fish oil compared to soybean oil supplemented diets. Main treatment effects interacted (P=0.005) for DMI of particles retained on 19 mm sieve but not for sorting index. Eating rate (0.090 kg of DM/min) was similar between barley- and corn-based diets, however, rumination time was greater for barley- compared to corn-based diets as result of longer rumination bout duration (32.5 vs. 28.5 min/bout; P=0.01). Barley- compared to corn-based diets increased total chewing time by 71 min (709 vs. 638 min) for cows fed fish oil, but not for cows fed soybean oil. Grain source did not affect milk yield or milk composition. Compared to soybean oil, fish oil negatively affected milk yield (40.4 vs. 43.4 kg/d; P=0.01), and thereby, both milk fat (0.91 vs. 1.26 kg/d; P<0.001) and protein (1.23 vs. 1.33 kg/d; P=0.007) production. However, feed efficiency (milk yield/DMI) was greater in fish oil compared to soybean oil supplemented diets (1.94 vs. 1.80; P=0.003). Results indicated that grain source and oil supplement can interact to affect feeding and chewing behavior, but not lactational performance of lactating cows.     

Welfare of lactating Holstein cows under outdoor grazing and indoor housing in relation to temperature and humidity in summer in Japan

Aim

The aim of this study was to investigate the differences in the physiological responses of lactating Holstein cows between outdoor grazing and indoor housing in summer in Japan.

Method

The cows (n=16) were grazed outside from indoor housing and returned indoors 3 weeks later, with a 1-week transition phase to mitigate each environmental change. Grazing cows remained in pasture except for milking twice per day and concentrate feeding before milking. Indoors, the cows were tethered except for milking twice per day and about 5.5 h of exercise in an open-air paddock.

Results

When the Temperature–Humidity Index (THI) threshold was above 72, urinary cortisol levels were higher only in the grazing phase. The indoor cows took a longer time to prepare to lie down compared with grazing cows.

Conclusions

This study suggests that forcing cows outside during hot weather can induce certain physiological stress responses in lactating Holstein cows. Cows exhibit more fluid lying-down movements on pasture, suggesting that the comfort of lying conditions of indoor housing was not ideal.     

The effect of grazing on cow mortality in Danish dairy herds

The effect of summer grazing in large Danish dairy herds and certain management characteristics of grazing were studied for their impact on dairy cow mortality. Mortality data (from the Danish Cattle Database) from 391 Danish dairy herds (>100 cows) were combined with information from a questionnaire survey of grazing procedures on these herds in 2008. In all, 131 of the herds were identified as summer grazing and 260 as zero-grazing herds. The mortality was affected by an interaction of summer grazing and milking system. The risk of a cow dying was reduced to 46% in a grazing compared to a zero-grazing herd having automatic milking system. In traditional milking system, mortality was reduced to 75% in grazing compared to zero-grazing herds. Within the grazing herds, the risk of mortality decreased with increasing number of hours on pasture during the season. Free access between barn and pasture was associated with increased cow mortality.     

Relationship of rumen fill and fermentation to diurnal and seasonal variation of herbage intake in dairy cows grazed on perennial ryegrass pasture

To clarify the effect of digesta weight in the reticulorumen on diurnal and seasonal fluctuations in herbage intake, six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture during morning and evening sessions in spring and autumn. The digesta weight of fresh matter, dry matter (DM) and fiber in the reticulorumen at the beginning and the end of each grazing session was lower in spring than in autumn (P < 0.01). Although the digesta weight was similar between the sessions at the beginning of grazing, it was greater for the evening than for the morning at the end of grazing (P < 0.01). The large particles proportion in the digesta was lower for the morning than the evening (P < 0.01), and it was lower in spring than in autumn (P < 0.01). The concentrations of volatile fatty acids in rumen fluid were generally higher in spring compared with autumn. The herbage DM intake during the evening was greater compared with the morning in both seasons (P < 0.01). However, there was no difference in herbage DM intake between seasons. The results showed that the rumen digesta fill was not the sole factor explaining diurnal and seasonal variation of herbage intake in grazing dairy cows.     

Herbage intake and ruminal digestion of dairy cows grazed on perennial ryegrass pasture either in the morning or evening

This study aimed to clarify diurnal fluctuations of herbage intake, ruminal fermentation of herbage carbohydrates and proteins, and digesta particulate weight in the rumen of grazing dairy cows. Six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture either in the morning (04.00 to 08.00 hours) or the evening (16.00 to 20.00 hours). Cows grazed in the evening spent more time (P < 0.01) and consumed more herbage (P < 0.01) compared with cows grazed in the morning. Higher (P < 0.05) daily mean concentrations of total volatile fatty acid, propionate and n‐butyrate in rumen fluid were observed for cows grazed in the evening compared with cows grazed in the morning. Although cows grazed in the evening ingested more crude protein compared with cows grazed in the morning, no significant difference in NH₃‐N concentration in rumen fluid was observed between them. The ratio of purine‐derivative concentration to creatinine concentrations was higher (P < 0.01) in the urine of cows grazed in the evening than in cows grazed in the morning. These results clearly indicated that evening grazing was advantageous for dairy cows compared with morning grazing, in terms of ruminal fermentable energy intake and nitrogen utilization efficiency.     

Influence of the calf presence during milking on dairy performance,milk fatty acid composition,lipolysis and cheese composition in Salers cows during winter and grazing seasons

The milking of Salers cows requires the presence of the calf. The removal of the calf would simplify the milking routine, but it could also modify the milk yield and the milk and cheese composition. Therefore, the aim of this experiment was to evaluate the effect of calf presence during milking during sampling period (winter or grazing periods), on dairy performance, milk fatty acid (FA) composition, lipolysis and cheese yield and composition. Nine and 8 Salers lactating cows were milked in the presence (CP) or absence (CA) of their calves respectively. During winter, the cows were fed a hay‐based diet and then they only grazed a grassland pasture. Calf presence during milking increased milk yield and milk 16:0 concentration and decreased milk fat content and milk total odd‐ and branched‐chain FA (OBCFA) concentrations. Calf presence only increased initial lipolysis in milk collected during the winter season. Milk from CP cows compared to CA cows resulted in a lower cheese yield and ripened cheeses with lower fat content. Milk from the grazing season had lower saturated medium‐chain FA and OBCFA concentrations and higher 18:0, cis‐9‐18:1, trans‐11‐18:1 and cis‐9, trans‐11‐CLA concentrations than that from the winter season. Initial milk lipolysis was higher in the winter than in the grazing season. These variations could be due to seasonal changes in the basal diet. Furthermore, the effect of calf presence during milking on milk fat composition was lower than that on dairy performance, cheese yield and composition. Removing the calf during the milking of Salers cows seems feasible without a decrease in milked milk, and with a positive effect on cheese yield and fat content, under the condition that we are able to select cows having the capacity to be milked easily without the calf.     

Dairy cow defecation and urination frequency and spatial distribution in relation to time-limited grazing

The objective of this paper was to investigate the effect of limited grazing time on urination and defecation frequency, spatial distribution of excrement in the paddock, and the resulting nitrogen balance at animal and field level. During a 6-week period in early summer, 60 Holstein Frisian dairy cows (31.0 ± 5.4 kg ECM) were randomly allocated to three different treatments, with grazing at clover-grass pasture during daytime for 4, 6.5 or 9 h daily. Indoor feeding, with a mixture of roughage and concentrates (13% crude protein), was restricted for treatment 4 and 6.5 h to the amount the 9-h treatment could eat. Cows allowed grazing at pasture for 4 h moved more rapidly during pasture, moved longer distance per active hour and used a higher proportion of the time eating, both at pasture and indoor, than the cows allowed longer time at pasture. Limiting the grazing time had no influence on the urination (mean = 0.26) and defecation (mean = 0.37) frequency per cow per hour during pasture. Even though the proportion of time active (eating, drinking, standing or walking), and the actual time active during pasture was different for the treatments, the frequency of urination and defecation per active hour was also unaffected by the treatments. Urine and faeces were distributed in the pasture, without specific hot-spots. The estimated daily N-balance at animal level showed increased N excretion with time at pasture. Assuming that excretion follows the active periods during the day and 7000 kg DM foliage is available on yearly basis, this would result in total excretion at field level of 58, 86 and 108 kg N per ha respectively for treatment 4, 6.5 and 9 h. The results of this experiment show that it is possible to reduce the nitrogen excretion in a grazing system by restricting the grazing time of dairy cows together with restricted indoor feeding while maintaining high foliage intake.     

The Effect of Subclinical Hypocalcaemia Induced by Na2EDTA on the Feed Intake and Chewing Activity of Dairy Cows

The effects of induced subclinical hypocalcaemia (SCHC) on feed intake and chewing activity during eating and rumination were studied in dairy cows. Two non-lactating and non-pregnant cows were subjected to three different treatments, with one test per day, such that the plasma free (ionized) calcium (_FCa) concentration was maintained at the eucalcaemic level or at one of two constant SCHC levels. The cows and test days followed a 2×3 crossover design. SCHC was maintained for 7 h by repeatedly infusing 5% Na₂EDTA so that constant _FCa concentrations of 0.8 mmol/L or 0.6 mmol/L in plasma were achieved. Control conditions were achieved by infusing isotonic saline. Feed intake and the number of the rumination periods were recorded during test days. The proportion of feed eaten during each test meal (EatPro) was related to the mean plasma _FCa. An almost linear decrease in EatPro was observed when the plasma _FCa was 0.6–0.9 mmol/L. The cows showed no other clinical signs of hypocalcaemia during Na₂EDTA-infusion. The time spent chewing during eating and rumination, and the number of rumination periods during a test day, decreased with a decline in plasma _FCa concentration.It was concluded that induced SCHC depresses the feed intake and ruminative activity of dairy cows.     

Effect of restricted suckling on milk yield,composition and flow,udder health,and postpartum anoestrus in grazing Holstein cows

The effect of restricted suckling on milk yield and composition, udder health, and postpartum anoestrus in dairy cows in pasture-based systems, was studied in 32 Holstein multiparous cows and their calves. At calving, each cow–calf pair was randomly assigned to one of two treatments: restricted suckling (RS) of the cows by her own or another calf, twice daily for 30 min or artificial rearing (AR) of the calves with milk obtained from the bulk tank, offered twice a day in buckets. Treatments were applied until week 8 after calving. The diet of the cows consisted of direct grazing in improved pastures, corn silage and a commercial concentrate which was offered at milking. Milk production and composition, udder health, body condition score of the cows, body weight and milk intake of the calves were measured weekly, and the first postpartum ovulation was determined three times a week by ovarian ultrasonography. Cows with RS management had a lower machine-milked milk yield (17.9 vs. 24.8 kg/d), a lower fat percentage (3.21 vs. 4.11%) and 4% fat-corrected milk yield (16.2 vs. 25.7 kg/d), and also a lower average milk flow (1.35 vs. 1.76 kg/min) than cows in the AR treatment. There was no effect of treatment on milk protein percentage or udder health as measured by milk electrical conductivity. The interval from calving to first postpartum ovulation was shorter in the AR cows than in the RS cows (18.5 vs. 21.8 days). The RS calves consumed more milk (7.2 vs. 5.4 kg/d), gained more body weight (0.813 vs. 0.656 kg/d), and had a higher body weight at weaning (84.3 vs. 73.3 kg) than AR calves. Restricted suckling of grazing dairy cows had a negative effect on machine-milked milk yield, fat percentage and 4% fat-corrected milk yield, but had no effect on udder health or on improved weight gain and body weight at weaning of the calves.     

Effects of feeding ratio of beet pulp to alfalfa hay or grass hay on ruminal mat characteristics and chewing activity in Holstein dry cows

The influence of the feeding ratio of a non‐forage fiber source and hay on ruminal mat characteristics and chewing activity was evaluated in dairy dry cows. Cows were fed four different diets: the ratios of alfalfa hay (AH) to beet pulp (BP) were 8:2 (dry matter basis, A8B2) and 2:8 (A2B8), and those of grass hay (GH) to BP were 8:2 (G8B2) and 2:8 (G2B8). Total eating time was decreased with increasing BP content (P < 0.01). Total rumination time for AH was shorter than that for GH (P < 0.01), and it decreased with increasing BP content (P < 0.01). The ruminal mat was detected by using a penetration resistance test of the rumen digesta. Penetration resistance value (PRV) of ruminal mat was highest with the G8B2 diet and PRV decreased with increasing BP content (P < 0.05) and feeding AH (P < 0.05). Thickness of the ruminal mat was greater for increasing BP content (P < 0.05). Simple linear regression of ruminal mat PRV on total rumination time resulted in a high positive correlation (r = 0.744; P < 0.001; n = 16). The results demonstrated that increasing the PRV of the ruminal mat stimulated rumination activity and a ruminal mat could be formed, although it was soft even when cows were offered a large quantity of BP.     

Evaluation of a Neck Mounted 2‐Hourly Activity Meter System for Detecting Cows About to Ovulate in Two Paddock‐Based Australian Dairy Herds

Two studies were conducted to assess the performance of a commercially available neck‐mounted activity meter to detect cows about to ovulate in two paddock‐based Holstein‐Friesian dairy herds. The activity monitoring system recorded cow activity count in 2‐hourly periods. Study I investigated the ability of the system to detect cow ovulatory periods in dairy herds managed in two different Australian environments and breeding systems using five activity alert algorithms. Herd 1 consisted of approximately 130 milking cows calving year‐round in a sub‐tropical environment and kept in a single dry lot paddock. Herd 2 consisted of approximately 400 milking cows calving seasonally in a temperate climate and fed pasture by rotation through multiple grazing paddocks. Ovulatory periods and non‐ovulatory days were identified using milk progesterone monitoring alone or in combination with ovarian ultrasonography; using these ‘gold standards’ 141 and 135 ovulatory periods were identified in 64 and 135 cows in Herds 1 and 2 respectively. Sensitivity of the activity monitoring system for detecting cow ovulatory periods ranged from 79.4% to 94.1%, specificity from 90.0% to 98.2% and positive predictive value from 35.8% to 75.8%. Study II investigated the ability of the activity meter system to predict the timing of ovulations in paddock‐based pasture‐fed dairy cattle (Herd 2). The time of ovulation was estimated by repeat trans‐rectal ovarian ultrasonography at approximately 0, 12, 24 and 36 h after artificial insemination (AI). The mean times (±SD) from onset and end of increased activity to ovulation were 33.4 ± 12.4 and 17.3 ± 12.8 h respectively (n = 94). Fifty per cent of cows (n = 47) ovulated within the 8‐h period between 30 to 38 hs after the onset of increased activity, 76.6% (n = 72) within the 16 h between 24 to 40 h, 85.1% (n = 80) within the 24 h between 18 and 42 h and 90.4% (n = 85) within the 32 h from 19 to 51 h after the onset of increased activity. Results from these studies show that in paddock‐based dairy cows in two diverse management systems, this neck‐mounted activity meter system detects high proportions of cows that are about to ovulate and provides a useful indication of when ovulation is likely to occur. However, the specificities and positive predictive values using the algorithms assessed may be lower than desirable.     

不同挤奶次数对奶牛产奶量的影响分析

[目的]分析增加挤奶次数对不同阶段泌乳奶牛产奶量的提升,找出最佳挤奶管理方案,为有效提升牧场效益提供理论依据。[方法]将泌乳牛只随机分为两组,保证不同胎次、不同产犊阶段平均泌乳量相当,分组后两组分别保持3次挤奶和4次挤奶1个月。对牧场不同挤奶次数奶牛泌乳量进行统计汇总整理分析。[结果]增加挤奶次数能有效提高奶牛泌乳量（P<0.05）;泌乳量高于45 kg奶牛增加挤奶次数对产奶量的提升,显著高于泌乳量低于45 kg的奶量（P<0.05）;增加挤奶次数显著提升头胎牛产量2.33 kg,二胎牛产量2.31 kg,三胎及以上牛奶产量2.78 kg(P<0.05);不同泌乳阶段,增加挤奶次数能有效提高泌乳初期及产奶高峰期的产奶量（P<0.05）。[结论]增加挤奶次数能有效提升奶牛泌乳量,对高产及处于产奶初期及高峰期的奶牛提升效果最佳。     

Dry matter intake and milk production of grazing dairy cows supplemented with corn silage or a total mixed ration offered ad libitum in a subtropical area

This study aimed to evaluate the feeding choice, dry matter (DM) intake, and milk production of dairy cows that strip grazed on a mixed perennial species pasture receiving different supplementation strategies. The treatments were without supplementation (WS) or with supplementation of either corn silage (CS) or a total mixed ration (TMR) based on CS and concentrates, in a subtropical area. The supplements were provided ad libitum after the afternoon milking. Twelve Holstein × Jersey cows in mid-lactation (133 ± 43 days in milk) were divided into six groups (two cows/group) and distributed in accordance with a replicated 3 × 3 Latin square design, with three 21 day periods (15 adaptation days and 6 evaluation days). The total DM intake, milk production, milk fat, and milk protein production were greater in the TMR treatment than in the WS and CS treatments and were similar between the WS and CS treatments. The herbage DM intake and proportion of time spent grazing were greater in the CS treatment than in the TMR treatment. CS supplementation did not affect the total DM intake or milk production/cow, whereas TMR supplementation greatly improved the total DM intake and milk production of the dairy cows grazing on mixed perennial species.     

The effect of feed regimen on chewing time, digesta passage rate and particle size distribution in Holstein non-lactating cows fed pasture ad libitum

The objective of this study was to evaluate the effect of feeding regimen on chewing activity and ruminal passage of digesta in non-lactating cows fed pasture ad libitum. Six ruminally fistulated Holstein dry cows (mean ± SD; parity = 3.7 ± 0.5, length of pregnancy = 28 ± 2 W, BW = 692 ± 75 kg) were assigned randomly to two dietary treatments using a crossover design; three cows were rotationally grazed pasture (treatment G) and the other was fed harvested pasture ad libitum in confinement (treatment C). Passage of digesta was measured by fecal marker excretion using Co-EDTA and Dysprosium (Dy) labeled grass as fluid phase maker or solid phase marker, respectively. Particle size distribution of ruminal digesta and feces was measured by wet sieving method. No significant difference in dry matter intake (DMI) between treatments was observed. Eating time in treatment G (517 min/day or 38.6 min/kg DMI) was longer treatment C (384 min/day or 31.0 min/kg DM). Chewing time per DMI was similar in both treatments (70.0 vs. 66.1 min/kg DMI). Ruminal liquid outflow rate and rumen volume of cows in treatment G were significant higher and lower than treatment C (9.9 vs. 12.2%/h and 111.0 vs. 79.9 L, respectively). The mean retention time in small particle pool to be able to pass through the reticulo-omasum orifice (CMRT₂) in cows of treatment C was longer (P < 0.05) than that for treatment G.. Logarithmic particle distribution and mean particle size of ruminal digesta at 24 h after feeding and feces particles had no significance between treatments. These results indicated that ingestive behavior of dry cow affected on eating time and ruminal volume, and it might have caused the higher ruminal liquid and particulate passage rate in treatment G compare to treatment C, with minimal effect on the particle size of digesta to pass from the rumen.     

Post-grazing sward height imposed during the first 10 weeks of lactation: Influence on early and total lactation dairy cow production,and spring and annual sward characteristics

Increasing the proportion of grazed grass in the diet of the dairy cow is the main target of grass-based milk production systems. Imposing a severe post-grazing sward height (PGSH) in early lactation is one strategy to increase grass utilisation. A grazing experiment was undertaken to investigate the direct and carryover effects of PGSH imposed in early lactation on sward and dairy cow lactation performance. Ninety Holstein–Friesian dairy cows (mean calving date: February 13) were randomly assigned to one of three target PGSH treatments: 2.7 cm (severe; S), 3.5 cm (low; L) and 4.2 cm (moderate; M) from February 14 to April 24, 2011 (period 1; P1). This was followed by a carryover period (period 2; P2) during which cows were randomly re-assigned within their P1 treatment across two PGSH treatments: 3.5 or 4.5 cm until November 13. Sward utilisation (>2.7 cm) during P1 was significantly improved by decreasing PGSH from M (0.74) to L (0.82) and further to S (0.94). At the end of the entire grazing season, the M treatment swards had produced +1.4 t dry matter (DM)/ha than the S and L treatment swards which had similar total DM yields (14.1 t DM/ha). Treatment had no immediate or carryover effect on the proportions of leaf, stem and senescent material in the sward or the quality of herbage selected by the animals. During P1 the cows in S had greater bodyweight loss (−18 kg), reduced milk (−2.1 kg/day) and milk solids yields (−0.21 kg/day) as well as lower grass DM intake (−1.7 kg DM/day) compared with the cows in L and M, which performed similarly (−5 kg, 24.1 kg/day, 1.94 kg/day, and 13.0 kg DM/day, respectively). There was no carryover effect of early lactation PGSH on milk and milk solids yields, fat and protein concentrations during P2. This indicates that cows restricted in P1 were able to adjust production in accordance with the higher PGSH imposed during the remainder of the lactation. The S treatment had numerically lower, though not significantly lower, total lactation milk and milk solids yields, reflecting their significantly reduced yields in early lactation. It was concluded that grazing to 2.7 cm in early lactation is too restrictive for dairy cows. Cows in L and M had very similar total cumulative production performance. As a result, grazing to 3.5 cm during the first 10 weeks of lactation contributes to achieving both high milk output from pasture and high grass utilisation.     

Associations between dairy herd management factors and bulk tank milk antibody levels against Ostertagia ostertagi

A cross-sectional questionnaire survey was performed on dairy herds in Flanders (Belgium) to detect management factors that are associated with an increased gastrointestinal parasite infection level of adult dairy cows. At the end of the grazing season, information concerning general herd factors, pasture management and anthelmintic treatment strategy was obtained from 956 herds. A bulk tank milk sample was obtained from 779 out of the 956 herds and the antibody levels (ODR) against Ostertagia ostertagi were determined. The associations between ODR and herd management factors were studied by two linear regression models. The first model evaluated the effect of general herd factors and the level of the cows' exposure to pasture. Large sized herds had significantly lower ODRs as compared to medium (P=0.001) or small sized herds (P=0.03). Herds with only dairy cows had lower ODRs than herds with both dairy and beef cows (P=0.02). An increased exposure to pasture of the cows was associated with higher ODRs (P<0.001). The second model was built to evaluate the effect of pasture management factors and anthelmintic treatment strategy. Later turn-out on pasture (P<0.001) and mowing (P=0.002) were both significantly associated with lower ODRs. Cows that had a restricted grazing time per day tended to have lower ODR than cows that grazed 24 h per day (P=0.07). An increased exposure to pasture of the heifers was significantly associated with higher ODRs (P=0.001). No associations were found between ODR and calf related management factors, anthelmintic treatment strategy, time of turn-in, rotational grazing type or stocking rate. Later turn-out on pasture, mowing and restricting the grazing time per day are factors that can be applied immediately on dairy farms to reduce economical losses due to gastrointestinal nematodes.     

Substitution of corn silage with shredded beet pulp affects sorting behaviour and chewing activity of dairy cows

This study aims to evaluate the effects of substituting increasing concentrations of shredded beet pulp (SBP) for corn silage (CS) on nutrient intake, sorting index, intakes of particle size and nutrients, meal and rumination patterns, and chewing activity of dairy cows. Four multiparous (126 ± 13 day in milk) and 4 primiparous (121 ± 11 day in milk) Holstein cows were used in a 4 × 4 Latin square design experiment with 4 periods of 21 days. Dietary treatments were (DM basis): 16% of dietary DM as CS without SBP (0SBP); 8% CS and 8% SBP (8SBP); 4% CS and 12% SBP (12SBP); and 0% CS and 16% SBP (16SBP). We observed a reduction in the extent of sorting against long particles and medium particles but for fine particles with increasing SBP levels in the diets. The number of eating bouts per day was lesser (8.2%) in cows fed SBP diets compared with 0SBP cows and corresponded with a reduction in eating time per d across treatments. The number of ruminating bouts per day was similar across diets (16.8 bouts/day), but substituting SBP for CS in the diets tended to decrease linearly ruminating bout length (5 min/bout) and tended to increase ruminating bout interval (8 min/day). Eating, ruminating and total chewing time when expressed as minutes per kilogram of forage NDF intake and peNDF > 8 intake increased when SBP was substituted for CS in the diets. Primiparous cows had greater ruminating time (57 m/day) and total chewing time (73 min/day), eating rate (0.01 kg of DM/min) compared with multiparous cows. Also, increasing forage NDF and peNDF_>8, >8‐mm DM intakes are effective means of stimulating ruminating and chewing activities. This study showed that SBP could partially replace CS and not affect DM intake, but chewing activity may decrease slightly.     

Effect of water‐soluble carbohydrate content in orchardgrass pasture on grazing time and rumen fermentation in dairy cows

Two experiments were conducted to clarify the effect of water‐soluble carbohydrate (WSC) content in orchardgrass pasture on the diurnal distribution of grazing time. Six ruminally cannulated, non‐lactating dairy cows were grazed on either of two pastures with different orchardgrass cultivars containing low WSC (LWSC; cultivar: ‘Hokkai 28’) or high WSC (HWSC; cultivar: ‘Harunemidori’). The cows were grazed in morning and evening sessions in experiment 1, whereas the cows were grazed throughout the day in experiment 2. In experiment 1, grazing time of the cows on HWSC was longer than that of the cows on LWSC (P < 0.01). This difference was larger in the morning session than in the evening session (pasture × grazing session: P < 0.05). Effects on herbage intake were similar to those on grazing time. In experiment 2, daily total grazing time was longer for the cows on HWSC than for those on LWSC (P < 0.05). The cows on HWSC spent a longer time grazing than those on LWSC in the morning between 03.00 and 09.00 hours (P < 0.01). The results indicated that prolonged grazing time in the period between dawn and early morning could increase daily herbage intake in cows grazed on pastures of orchardgrass cultivars with high‐WSC content.     

A multilevel model with clustered management practices differentiating dairy herd environments in southeastern Sicily

Herd environments constitute productivity potentials, or aggregate opportunity outcomes, resulting from management actions taken with the available inputs. Management outcomes from cow nutrition, udder health and milking practices were quantified with the help of surveys of 254 dairy producers in southeastern Sicily. Objectives were to disentangle environmental opportunities by disaggregating herd effects into causal inputs. Average ME milk production was 8640 kg/lactation for the 183 Friesian herds containing 35 lactating cows and 10 dry cows. Seventy-one Brown Swiss herds averaged 6443 kg ME milk from 25 lactating and 10 dry cows. For Friesian (Brown Swiss) herds 10 (11) management practices affected milking performance and 9 (8) practices influenced somatic cell concentration (P<0.05). Multilevel analysis and herd clustering procedures differentiated low from high opportunity herd environments but altering relative weightings among management practices did not further discriminate them. This clustering methodology helps ensure unbiased estimation of management input effects and could help target priority management substitutions and technical support priorities in dairy extension programs.