Effects of the percentage of concentrate on rumen fermentation, nutrient digestibility, plasma metabolites, and milk composition in mid-lactation goats

The aim of this work was to study the effects of the dietary percentage of concentrate on patterns of intake, the evolution of rumen fermentation characteristics and plasma metabolites after a meal, nutrient digestibility, and milk production and composition in a medium-term trial in dairy goats. These effects have been well studied in dairy cattle but seldom in goats. Thirteen ruminally and duodenally cannulated dairy goats (95 ± 4 d in milk) fed ad libitum were used in this study. Goats were assigned to 1 of 2 dietary treatments: high-concentrate (70% concentrate on dry matter basis) or a low-concentrate (35%) total mixed rations. The experiment was conducted over a period of 10 wk, including 3 wk of adaption to the diets. Patterns of intake, rumen fermentation characteristics, and plasma metabolites after a meal and fatty acids profile of milk fat were compared at the onset and at the end of the experiment. The increase in dietary percentage of concentrate decreased rumen pH, acetate to propionate ratio, ammonia-N concentration, and plasma urea concentration. The percentage of concentrate did not affect total volatile fatty acid concentrations. The high-concentrate diet increased the rate of intake during the morning meal at the onset of the experiment, whereas it decreased total dry matter intake and the rate of intake during the morning meal at the end of the experiment. The high-concentrate diet resulted in greater organic matter digestibility. Raw milk yield and protein yield were greater in goats fed the high-concentrate diet, whereas fat yield was not affected by dietary treatments. The milk fat content was lower in goats fed the high-concentrate diet. Proportions of the trans-C18:1 isomer relative to total fatty acids in milk were higher with the high-concentrate diet, but no modification of the proportion of total trans-C18:1 was detected, in particular no shift from trans-11 C18:1 to trans-10 C18:1 was observed. Further, the isomer trans-10,cis-12 C18:2 was not detected. Data from this study could be used for a new modeling approach or to improve existing models.     

Effects of essential oils on rumen fermentation, milk production, and feeding behavior in lactating dairy cows

Seven ruminally cannulated lactating Holstein dairy cows were used in an incomplete Latin rectangle design to assess the effects of 2 commercial essential oil (EO) products on rumen fermentation, milk production, and feeding behavior. Cows were fed a total mixed ration with a 42:58 forage:concentrate ratio (DM basis). Treatments included addition of 0.5 g/d of CE Lo (85 mg of cinnamaldehyde and 140 mg of eugenol), 10 g/d of CE Hi (1,700 mg of cinnamaldehyde and 2,800 mg of eugenol), 0.25 g/d of CAP (50 mg of capsicum), or no oil (CON). Cows were fed ad libitum twice daily for 21 d per period. Dry matter intake, number of meals/d, h eating/d, mean meal length, rumination events/d, h ruminating/d, and mean rumination length were not affected by EO. However, length of the first meal after feeding decreased with addition of CE Hi (47.2 min) and CAP (49.4 min) compared with CON (65.4 min). Total volatile fatty acids, individual volatile fatty acids, acetate:propionate ratio, and ammonia concentration were not affected by EO. Mean rumen pH as well as bouts, total h, mean bout length, total area, and mean bout area under pH 5.6 did not differ among treatments. Total tract digestibility of organic matter, dry matter, neutral detergent fiber, acid detergent fiber, crude protein, and starch were not affected by EO. Milk yield and composition did not change with EO. In situ dry matter disappearance of ground soybean hulls was not affected by EO. However, organic matter disappearance of soybean hulls with CE Hi tended to decrease compared with CON. Compared with CON, neutral detergent fiber disappearance (41.5 vs. 37.6%) and acid detergent fiber disappearance (44.5 vs. 38.8%) decreased with addition of CE Hi. The CE Lo had no effect on rumen fermentation, milk production, or feeding behavior but CAP shortened the length of the first meal without changing rumen fermentation or production, making it a possible additive for altering feeding behavior. The CE Hi negatively affected rumen fermentation and shortened the length of the first meal, suggesting that a dose of 10 g/d is not beneficial to lactating dairy cows.     

The use of a multivariate analysis to study between-goat variability in feeding behavior and associated rumen pH patterns

This study examined feeding patterns and their relation to rumen pH. The measured variables were the cumulative time spent chewing (eating or ruminating) and the mean rumen pH, per 20-min intervals (46 intervals altogether). A total of 333 feeding patterns, defined as time-series of measurements for 1 animal and 1 given day during 15 h and 20 min following the afternoon feeding, were collected from 12 stall-housed dairy goats fed a total mixed ration twice daily. The first objective of this study was to analyze the within-day variability of feeding behavior to characterize different feeding patterns. The second objective was to analyze, for each goat, the between-day variability of its feeding behavior. The third objective was to study the influence of feeding behavior on rumen pH. A multivariate method (principal component analysis) was performed on the time spent eating or ruminating during each of the 46 intervals. The factor score plots generated by the principal component analysis highlighted the evolution in time of chewing activities. They also were used to determine 4 different types of feeding behavior in the extreme patterns of the first 2 axes. These feeding patterns were associated with different rumen pH patterns in goats with the same total dry matter intake and mean rumen pH. Some goats had a major eating period immediately after feeding, followed by a period of rumination; this pattern was associated with a marked decrease in rumen pH and a pH nadir below 6.0. Other goats performed alternate periods of eating and ruminating throughout the studied period. The latter feeding pattern was associated with a shorter total duration of rumination, but a more stable rumen pH than the feeding pattern described previously. Feeding pattern was quite constant between days for some goats, but highly variable for others. However, the continuum observed between these 4 groups shows that many intermediate types of behavior can be observed. In conclusion, characterizing animals according to their feeding behavior by using a principal component analysis may provide information on the animal's predisposition to rumen acidosis.     

Effects of the chop lengths of alfalfa silage and oat silage on feed intake, milk production, feeding behavior, and rumen fermentation of dairy cows

Effects of chop length (shorter: 6 mm, or longer: 19 mm) of alfalfa silage and oat silage were determined in 16 mid-lactation Holstein cows, 4 of which were rumen cannulated, using a replicated 4 × 4 Latin square design with a 2 × 2 arrangement of treatments. Experimental periods were 21 d long and consisted of 14 d of adaptation and 7 d of sampling. Cows received a total mixed ration containing [dry matter (DM) basis] 42.0% barley grain-based energy supplement, 10% protein supplement, and 24% of DM longer chop or shorter chop alfalfa silage and 24% of DM longer chop or shorter chop oat silage. Rumen pH was measured continuously, and rumen liquid flow rates were determined in rumen-cannulated cows. Feeding behavior was determined by videotaping, and meal patterns were determined by continuously weighing the feed in the bunk of 8 cows. Reducing the chop length of alfalfa silage and oat silage reduced the average geometric particle length from 14.2 to 10.9 mm and from 13.4 to 10.4 mm, respectively. Reducing the alfalfa chop length did not affect feed intake, whereas reducing the oat silage chop length increased DM intake from to 19.4 to 21.2 kg/d. Reducing the chop lengths of alfalfa silage and oat silage chop length did not affect milk production, rumen fermentation, feeding behavior, meal patterns, and blood metabolites. Daily milk yield, milk fat percentage, and milk protein percentage averaged 36.1 kg/d, 3.00%, and 3.16%, respectively, across diets. The low milk fat percentages suggest that the diets induced subacute ruminal acidosis. This was also substantiated by the rumen pH, which was below 5.6 for more than 122 min/d for all diets. The onset of subacute ruminal acidosis despite apparently adequate dietary neutral detergent fiber content and particle size distribution as well as the long duration of chewing might be attributed to sorting against long feed particles.     

Effects of stage of lactation and dietary concentrate level on energy utilization by Alpine dairy goats

Twenty-four lactating and 13 nonlactating Alpine goats were used to determine effects of stage of lactation and dietary concentrate level on energy utilization. Diets comprising 60 or 20% concentrate (60%C and 20%C, respectively) were consumed ad libitum by lactating animals and at a level of intake near maintenance by nonlactating animals. Measurement periods were d 25 to 31 (early), 87 to 94 (mid), and 176 to 183 (late) of lactation. Eleven observations were made in early and mid lactation for each diet, and 8 and 7 were made in late lactation for the 60%C and 20%C diets, respectively. Efficiency of metabolizable energy (ME) use for maintenance (66.9, 71.4, and 61.1% for early, mid, and late lactation, respectively) and the maintenance ME requirement (479, 449, and 521 kJ/kg of BW^0.75 for early, mid, and late lactation, respectively) determined with nonlactating animals differed among stages of lactation. The efficiency of ME use for maintenance was similar between diets, but the maintenance requirement tended to be greater for the 60%C than for the 20%C diet (504 vs. 463 kJ/kg of BW^0.75). The latter difference may have involved greater ME intake for the 60%C diet, resulting in a slightly greater difference between ME intake and total heat energy for the 60%C compared with the 20%C diet (11 vs. −8 kJ/kg of BW^0.75). Intake of ME by lactating goats was greater for the 60%C than for the 20%C diet (18.6 vs. 16.3 MJ/d). Recovered energy in lactation from mobilized tissue tended to be greater for the 60%C than for the 20%C diet (8.44 vs. 6.55 MJ/d) and differed among stages of lactation (2.60, 1.59, and 1.13 MJ/d in early, mid, and late lactation, respectively). Recovered energy in tissue gain was similar among stages of lactation and between diets and was not different from 0. Efficiency of use of dietary ME for lactation differed among stages of lactation (59.5, 51.9, and 65.4% for early, mid, and late lactation, respectively) and tended to be greater for the 60%C than for the 20%C diet (64.2 vs. 54.9%). The efficiency of use of dietary ME for maintenance and lactation was similar among stages of lactation and was greater for the 60%C compared with the 20%C diet (64.3 vs. 60.9%). Predicted milk yield from National Research Council requirements was reasonably accurate. In conclusion, using data of nonlactating goats to study energy utilization for maintenance in lactation has limitations. Efficiency of energy use by lactating dairy goats consuming diets high in concentrate appears greater than that by goats consuming diets low in concentrate. Despite differences in nutrient requirement expressions, observations of this study support National Research Council recommendations of energy requirements of lactating dairy goats.     

Effect of feeding space on the inter-cow distance, aggression, and feeding behavior of free-stall housed lactating dairy cows

The objectives of this study were to determine whether doubling the amount of feeding space from 0.5 to 1.0 m per cow leads to increased spacing between cows at the feeder, fewer aggressive social interactions among cows, and ultimately increased feeding activity. Twenty-four lactating Holstein cows were provided with 0.5 and 1.0 m of feeding space per cow in a 2 x 2 crossover design replicated over time. Time-lapse video was used to quantify the inter-cow distance and incidence of aggressive displacements at the feed alley. An electronic feed alley monitoring system was used to monitor the feeding behavior of the cows. When animals had access to 1.0 m per cow, there was at least 60% more space between animals and 57% fewer aggressive interactions while feeding than with access to 0.5 m of feeding space. These changes in spacing and aggressive behavior in turn allowed cows to increase feeding activity throughout the day, especially during the 90 min after providing fresh feed (an increase of 24%). This increase in feeding activity was particularly evident for subordinate cows. These results indicate that increasing space allowance at the feeder increases feeding activity and reduces competition among lactating dairy cows.     

The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves

We investigated the interactive effects of common feeding management factors on the development of feeding and non-nutritive oral behaviors in preweaned calves through the weaning transition. Calves were randomly assigned to 1 of 3 treatments that differed by milk-feeding method (teat or bucket) and ad libitum access to chopped timothy hay: control, milk provided by bucket and no access to hay (CON; n = 10); milk provided by bucket and access to hay (H; n = 10); milk provided via a teat and access to hay (TH; n = 10). Calves had ad libitum access to concentrate and water, and were fed 6 L/d of pasteurized waste milk, divided into 2 meals. All calves were weaned by removing the second milk meal for 9 ± 2 d, beginning at 36 d of age. Daily concentrate and hay intake were recorded, and calves were weighed weekly to measure growth. We recorded the behavior of all calves using 2 s time-lapse video during time periods that encompassed milk meals, from 6000 h to 1000 h and 1600 h to 2000 h, on 2 consecutive focal days in wk 2 and 4. We continuously monitored lying time and activity using electronic data loggers. During the preweaning period, hay selection by H and TH calves was subject to a treatment × week interaction, with TH calves increasing hay intake to a greater extent over time. Similarly, we observed a tendency for a treatment × week interaction for hay dry matter intake. Before weaning, concentrate intake was subject to a treatment × week interaction, increasing to a greater extent over time for H and TH calves, but was greater overall for CON calves. As predicted, milk-feeding method and hay provision influenced the proportion of time devoted to feeding and non-nutritive behaviors. The CON calves spent the greatest amount of time performing non-nutritive sucking directed at the pen, TH calves the least, and H calves intermediate amounts. Considering the time TH calves sucked on their teat when milk was not present in addition to the time they spent sucking on pen fixtures, the total amount of time spent performing sucking behavior was similar between treatments. Although intake was similar across the weaning transition, CON calves had greater average daily gain than H calves, and TH calves were intermediate. Providing access to hay and milk via a teat during the milk-feeding stage decreased non-nutritive oral behaviors and influenced feeding behavior.     

Effect of prepartum grouping strategy on displacements from the feed bunk and feeding behavior of dairy cows

The objective of the current study was to determine whether providing stable pen management affected displacements from the feed bunk and feeding behavior of prepartum dairy cows. Two hundred and twenty-four nonlactating Jersey primiparous and multiparous cows were enrolled in the study. The 2 treatments were all-in-all-out (AIAO; 44 cows were moved into the close-up prepartum pen as 1 group, with no additions during the 5-wk repetition) or traditional (TRD; with weekly entrance of new cows to maintain a pen density of 44 cows). Cows (253 ± 3 d of gestation) were balanced for parity and projected 305-d mature-equivalent milk yield and assigned randomly to either AIAO or TRD treatments. At enrollment, cows with a body condition score <2 or >4 (1–5 scale; 1 = emaciated and 5 = obese) or with a locomotion score >3 (1–5 scale; 1 = normal gait and 5 = severely lame) were not included. Displacements from the feed bunk were measured weekly for both treatments when TRD cows were moved into the close-up pen (d 0) and additionally on d 1, 2, 3, and 7 for 3 h after fresh feed delivery. A displacement rate was created to take into account differences in stocking density throughout the experiment. Displacement rate was calculated as the number of displacements divided by the number of cows in the pen at that time. Feeding behavior was measured using video 10-min scan sampling for 24-h periods at d 0, 1, 2, and 7. Displacements and feeding behavior were recorded for all 5 wk of each repetition. Treatment × week interactions were detected for number of displacements and displacement rate. The TRD treatment had more displacements from the feed bunk than AIAO in wk 1, 3, and 5, with no differences in wk 2 and 4. Similarly, the TRD treatment had a greater displacement rate than the AIAO treatment in wk 1 and 5, with a tendency in wk 3. No differences between the treatments were detected in wk 2 and 4. A treatment × week interaction existed for feeding time. Cows housed in the AIAO treatment had longer average feeding times in wk 2 with a tendency in wk 3, but spent 39 fewer minutes eating than those in the TRD treatment during the wk 1 of the study. Housing prepartum close-up cows with stable pen management reduced displacements from the feed bunk and altered average daily feeding times.     

Measuring the feeding behavior of lactating dairy cows in early to peak lactation

The objectives of this study were to: 1) objectively define meal criteria (minimum interval between meals) of free-stall housed cows fed via a feed alley, 2) determine which measures of feeding behavior were most repeatable, and 3) describe changes in the feeding behavior from early to peak lactation. An electronic monitoring system was used to record individual cow presence (hits; 6-s resolution) at the feed alley for 21 lactating cows for three 8-d periods: period 1, 35 +/- 16 (mean +/- SD), period 2, 57 +/- 16, and period 3, 94 +/- 16 DIM. A mixture distribution model was used to calculate the meal criterion (27.74 min) by fitting the log10 frequency distribution of the intervals between hits. The within-cow repeatability was highest for feeding activity (hits d(-1)) and intensity (hits per meal min), moderate for total daily mealtime (min d(-1)) and meal duration (min meal(-1)), and lowest for meal frequency (meals d(-1)). From periods 1 to 2, all cows showed increases in total daily mealtime, meal frequency, and meal duration; however, cows with lower meal frequencies and feeding intensity in period 1 showed the greatest increases. Cows with high feeding activity and intensity during period 2 showed proportionally greater increases during period 3. These results illustrate that some measures of feeding behavior are highly repeatable within cows, but variable between cows and across stages of lactation. Thus, tests of treatment effects on feeding behavior should be within cow and control for days in milk.     

Short-term responses in production and behavior during periods of change in concentrate allowance for dairy cows

The aim of this study was to investigate the short-term responses of dairy cows during periods of change in the concentrate allowance in an automatic milking system. The experiment had a design with a 2 × 2 factorial arrangement including 2 types of concentrates and 2 amounts of concentrates (type O: mix of pelleted concentrate and steamrolled, acidified barley; type S: pelleted) in amounts of 3 and 6 kg/d. The experiment length was 11 wk. The concentrate type changed between wk 6 and 7 and included both increase and decrease in concentrate allowance for each concentrate type. The concentrate allowance was changed by 0.5 kg/d over 6 d. The 96 cows (48 Danish Jersey, 48 Danish Holstein) included in the experiment were blocked according to breed, parity, and days in milk, and randomly divided into 8 groups of treatment order. The cows visited the automatic milking unit more often when concentrate type O was offered, but not when an increased concentrate allowance was provided. The changes in concentrate intake and partial mixed ration (PMR) eating time showed a symmetrical pattern between the periods of increasing allowance and decreasing allowance. However, PMR intake and milk yield varied in the magnitude of the responses, indicating that these responses may not be driven by the same underlying mechanisms during increase and decrease in concentrate allowance. The daily lying time increased and the PMR eating rate decreased during periods of both increase and decrease in concentrate allowance. We found no significant change in milk yield during increase in concentrate allowance, despite a higher milk yield during periods with constant concentrate allowance at the high concentrate amount; however, the milk yield decreased during periods of decrease in concentrate allowance. Visit frequency, lying time, and steps changed during periods of changes in concentrate allowance without showing any differences at the constant concentrate allowance. In conclusion, these results indicate that it may be difficult to adjust the individual concentrate allowance based on the short-term responses of the cow.     

Technical note: a computerized system for monitoring feeding behavior and individual feed intake of dairy cattle

The objective of this study was to develop and validate a computerized system to monitor feeding behavior and feed intake of loose-housed dairy cattle. The system consisted of 28 scales located in front of each self-locking place of a regular feedbunk. All cows had access to all scales indifferently. Each visit to the feedbunk was monitored by a transponder in the ear of each cow that was detected by a proximity reader located at the top right corner of each headlock. The data from the scales and the proximity readers were continuously recorded by a computer with an average scanning time of 3.5 s. The monitoring system was validated using all 28 feeding places and 51 lactating cows in a series of 4-h observations during 5 different d. During the observation periods, for each feeder, 2 observers recorded the cow number and the exact time of the visit. The observed data were then compared with the computer records. To validate the ability of the system to monitor feed consumption, on separate days, the amount of feed consumed by a cow during a visit was also measured manually with an external scale, and the feed that disappeared from each scale in 2 different 24-h periods was compared with the sum of feed consumed in each scale during these 2 periods. The average time spent in a given scale by each cow determined by direct observations was similar to that determined by the computer. The system was accurate and showed a high specificity (98.8%) and sensitivity (99.6%) for cow detections. Feed weights determined by the computer system were similar to those measured manually with an external scale, implying that the system was also accurate in measuring individual intake weights. In conclusion, the system provided a reasonable estimate of the number of visits per animal, length of each visit, amount of feed consumed per visit and animal, the total amount of feed consumed daily by each animal, and the rate at which animals consume feed.     

Relationship between feeding strategy, lying behavior patterns, and incidence of intramammary infection in dairy cows

The objectives of this study were to investigate whether feeding strategy influences post-milking standing time in dairy cows and to determine whether this time relates to incidence of intramammary infection (IMI). Fifteen lactating dairy cows (5 most recently fresh, 10 randomly chosen) from each of 6 tie stall dairy farms were enrolled for a total of 90 cows. Quarter samples of milk were taken from each cow once every 3 wk for a total of 3 samplings, and routine bacteriological culture and identification procedures were conducted. National Mastitis Council guidelines were used to define IMI, and occurrence of a new IMI was defined as a positive culture sample following a negative culture sample. Data on lying behavior patterns were collected using data loggers for every cow for 7 d before each milk sampling. For these 7 d, individual milking and feeding times of the cows were also recorded. Our results demonstrated that the provision of feed around milking time (between 30 min before and 60 min after) resulted in the longest post-milking standing times. The shortest post-milking standing times were seen in those cows that were fed >30 min before milking. Feeding cows >60 min after milking resulted in only slightly shorter post-milking standing times than those fed between 30 min before and 60 min after milking. Cows lying down for the first time 40 to 60 min after milking had 1.4 times lower odds of acquiring a new environmental IMI than cows lying down within 40 min after milking. As post-milking standing time increased past 60 min, the odds of acquiring a new environmental IMI increased as well. The cows lying down for the first time 60 to 90, 90 to 120, and >120 min after milking showed 3.2, 5.8, and 7.4 times higher odds, respectively, of acquiring a new environmental IMI compared with cows lying down for the first time within 40 min of milking. Our results suggest that despite being able to manage post-milking standing times by providing fresh feed at different times around milking, the use of such a feeding strategy in tie stall systems is an unrealistic IMI prevention strategy.     

Technical note: validation of methodology for characterization of feeding behavior in dairy calves

Time sampling techniques are useful in collecting feeding behavior data because they minimize the time required for observation. Instantaneous recording is often used in the collection of feeding behavior data for dairy calves; however, the recording intervals used vary widely and it is unclear what minimum interval is necessary to yield accurate data. The objective of this study was to validate data obtained using instantaneous recording of feeding behavior of dairy calves across a range of time intervals with data obtained from continuous recording. Ten Holstein bull calves were observed continuously using time-lapse video for 3 d during the milk-feeding period while they were fed milk ad libitum and for 3 d post-milk-weaning while they consumed solid feed. Feeding behavior data obtained from continuous recording were compared with data obtained from instantaneous recording at intervals ranging from 15 s to 10 min. As expected, the strength of linear association between behavior measures obtained from continuous recording and instantaneous recording decreased with increasing recording interval. The relationship varied between feeding behavior measures; feeding time was represented well (R² >0.76) by instantaneous recording at up to 5-min intervals, but a strong linear association of meal frequency and meal time (R² >0.8) required intervals no greater than 1 min and 30 s, respectively. The relationship between feeding behavior measures obtained from continuous recording and recording at different intervals was similar in both periods; however, sensitivity of time sampling data across recording intervals was greater during the milk-feeding period. Sensitivity was low in both periods (<0.7 with scanning intervals as short as 1 min), indicating that instantaneous recording may not represent within-meal feeding behavior well. Instantaneous recording can provide accurate calf feeding behavior data if the recording interval is sufficiently short.     

Effect of dietary physically effective fiber on ruminal fermentation and the fatty acid profile of milk in dairy goats

The objective of this experiment was to characterize the relationship among rumen fermentation variables, milk fatty acid profile, and dietary physically effective neutral detergent fiber (peNDF) content in a study that controlled for the potential confounding effects of dissimilar dry matter intake among treatments. Ten multiparous Xinong Saanen dairy goats were divided into 2 groups with 2 ruminally cannulated goats per group. Goats in each group were assigned to 1 of 2 dietary treatments (high and low peNDF) according to a 2 × 2 crossover design with 2 periods. The peNDF content of alfalfa hay (proportion of neutral detergent fiber retained on an 8.0-mm screen) was 42.1% for the high-peNDF and 14.5% for the low-peNDF group. To ensure similar dry matter intake, each morning the amount of alfalfa hay consumed on the prior day by the high-peNDF group was determined (amount offered minus morning refusals), and this was the amount of hay offered to the low-peNDF group that day. Each adaptation period consisted of 21 d, followed by a 9-d sampling period. Dry matter intake and milk production and composition were similar between treatments. Milk energy efficiency increased with low dietary peNDF. Duration of pH below 5.60 was longer for goats fed the low-peNDF ration compared with the high-peNDF ration (4.08 vs. 0.41 h/d); however, mean rumen pH (6.05 vs. 6.13) was not different between treatments. Reducing dietary peNDF increased rumen total volatile fatty acids (114.6 vs. 95.1 mM) and decreased chewing time (404 vs. 673 min/d), but did not affect the ratios of acetate, propionate, and butyrate. The relative abundance of Fibrobacter succinogenes and Ruminococcus flavefaciens increased with reduced dietary peNDF, but Ruminococcus albus proportions were not influenced by treatment. Reducing dietary peNDF decreased the proportion of iso C14:0, iso C15:0, and trans-11 C18:1 in milk fat, whereas the iso C17:0 and trans-10 C18:1 increased. This study demonstrated that low dietary peNDF in dairy goats increases rumen volatile fatty acids, reduces chewing time, and is correlated to the amount of F. succinogenes and R. flavefaciens.     

Relationships between rumen lipopolysaccharide and mediators of inflammatory response with milk fat production and efficiency in dairy cows

The main objective of this study was to evaluate correlative relationships between rumen lipopolysaccharide (LPS) and mediators of acute phase response with milk fat yield and efficiency in dairy cows challenged with graded amounts of barley grain in the diet. An additional aim of the study was to quantify the intercow variation in relation to milk fat production and acute phase response in cows fed graded amounts of grain. Eight primiparous, lactating Holstein cows (60 d in milk) were assigned to 1 of the 4 total mixed rations containing barley grain at 0, 15, 30, and 45% (dry matter basis) in a replicated 4 × 4 Latin square design. Free rumen LPS, plasma acute phase proteins, and milk fat content were quantified in multiple samples collected on d 5 and 7 of the measurement periods shortly before the morning feeding. Results showed markedly greater concentrations of rumen LPS with increasing dietary grain level. The correlative analysis revealed strong negative relationships between rumen LPS and milk fat content and yield. The predictor variable of rumen LPS explained 69% of the variation during the milk fat reduction of the cows. The stronger depression in milk fat percentage was obtained when rumen LPS exceeded a threshold of 5,564 ng/mL, corresponding to a milk fat content of 3.39%. The increase in concentration of rumen LPS was also associated with declines in milk fat yield and 3.5% fat-corrected milk (R² = 0.50), as well as milk energy efficiency (R² = 0.43). The correlative analysis also indicated that the increase of plasma C-reactive protein (CRP) in response to higher grain feeding was associated with a linear decrease of milk fat content and yield (R² = 0.28 to 0.46). Furthermore, the statistical analysis revealed high percentages of intercow variation related to milk fat variables, as well as the responses of rumen LPS and plasma CRP. Taken together, the current results implicate rumen LPS and the host CRP response in the lowering of milk fat content and milk energy efficiency in dairy cows fed high-grain diets. Further research is warranted to understand the mechanism(s) by which rumen LPS and inflammatory responses to LPS lower milk fat synthesis and milk energy efficiency and to develop novel strategies for their prevention.     

Effect of dietary inclusion of winter brassica crops on milk production,feeding behavior,rumen fermentation,and plasma fatty acid profile in dairy cows

This study determined feeding behavior, dry matter (DM) intake (DMI), rumen fermentation, and milk production responses of lactating dairy cows fed with kale (Brassica oleracea) or swede (Brassica napus ssp. napobrassica). Twelve multiparous lactating dairy cows (560 ± 22 kg of body weight, 30 ± 4 kg of milk/d, and 60 ± 11 d in milk at the beginning of the experiment; mean ± standard deviation) were randomly allocated to 3 dietary treatments in a replicated 3 × 3 Latin square design. The control diet comprised 10 kg of grass silage DM/d, 4 kg of ryegrass herbage DM/d, and 8.8 kg of concentrate DM/d. Then, 25% of herbage, silage, and concentrate (DM basis) was replaced with either kale or swede. Cows offered kale had decreased total DMI compared with cows fed the control and swede diets, whereas inclusion of swede increased eating time. Milk production, composition, and energy-corrected milk:DMI ratio were not affected. Cows fed with kale had a greater rumen acetate:propionate ratio, whereas swede inclusion increased the relative percentage of butyrate. Estimated microbial N was not affected by dietary treatments, but N excretion was reduced with inclusion of kale, improving N utilization. Cows fed kale tended to have increased nonesterified fatty acids and showed presence of Heinz-Ehrlich bodies, whereas hepatic enzymes such as aspartate aminotransferase, γ-glutamyl transferase, and glutamate dehydrogenase were not affected by dietary treatments. In plasma, compared with the control, swede and kale reduced total saturated fatty acids and increased total polyunsaturated fatty acids and total n-3 fatty acids. Overall, feeding cows with winter brassicas had no negative effect on production responses. However, mechanisms to maintain milk production were different. Inclusion of swede increased the time spent eating and maintained DMI with a greater relative rumen percentage of butyrate and propionate, whereas kale reduced DMI but increased triacylglycerides mobilization, which can negatively affect reproductive performance. Thus, the inclusion of swede may be more suitable for feeding early-lactating dairy cows during winter.     

Short communication: Effects of mammary biopsy in the dry period on activity and feeding behavior of dairy cows

In dairy cattle, mammary biopsies are commonly used to study development and function of the mammary gland. The objective of this study was to investigate changes in activity and feeding patterns following the mammary biopsy procedure. Pregnant, nonlactating Holstein dairy cows (20 d before expected calving date) were exposed to either (1) a biopsy procedure, in which a mammary tissue sample (60 × 4 mm in diameter) was obtained from cows (n = 9) using a biopsy tool from the rear left quarter, following administration of a sedative (xylazine, 20 µg/kg of body weight) and local anesthetic (3 mL of lidocaine), or (2) a sham procedure, in which cows (n = 8) were removed from the pen and restrained for a similar duration of time as for the biopsy procedure. Behavior of cows was monitored for 5 d, beginning on the day following biopsy (approximately 14 h after the procedure). Cows were fitted with accelerometers to record daily lying time, lying bout frequency, and lying side. Daily individual feed intake was recorded using the Calan Broadbent feeding system, and feeding time and meal characteristics were determined from a subset of cows (n = 6 per treatment) using a change-of-state data logger to record the times the cows were accessing the feed bunk. Total daily lying time did not differ between treatments [13.9 h/d; standard error (SE) = 0.56], but biopsied cows had more frequent, shorter lying bouts on the biopsied side on d 1 following the procedure (6.67 vs. 4.25 bouts/d, SE = 1.03, and 70.0 vs. 97.0 min/bout, SE = 8.6; left vs. right side), whereas control cows had no side preference. We found no effects of treatment on feed intake and feeding time but, on the first day after treatment, biopsied cows had meals that were more frequent (7.2 vs. 4.6 meals/d; SE = 0.93) and tended to be shorter (28.2 vs. 60.9 min/meal; SE = 11.8) than control cows. In conclusion, we did not detect effects of mammary biopsy on feed intake or lying time during our time frame of observation, but activity patterns were altered, which could be indicative of increased overall restlessness and specific pain in the biopsied quarter.     

The effect of supplemental concentrate fed during the dry period on morphological and functional aspects of rumen adaptation in dairy cattle during the dry period and early lactation

Ten rumen-cannulated Holstein-Friesian cows were used to examine the effect of feeding supplemental concentrate during the dry period on rumen papillae morphology and fractional absorption rate (k_a) of volatile fatty acids (VFA) during the dry period and subsequent lactation. Treatment consisted of supplemental concentrate [3.0 kg of dry matter (DM)/d] from 28 d antepartum (ap) until the day of calving, whereas control did not receive supplemental concentrate. Cows were fed for ad libitum intake and had free access to the dry period ration (27% grass silage, 28% corn silage, 35% wheat straw, and 11% soybean meal on a DM basis) and, from calving onward, to a basal lactation ration (42% grass silage, 42% corn silage, and 16% soybean meal on a DM basis). From 1 to 3 d postpartum (pp), all cows were fed 0.9 kg DM/d of concentrate, which increased linearly thereafter to 8.9 kg of DM/d on d 11 pp. At 28, 18, and 8 d ap, and 3, 17, 31, and 45 d pp, rumen papillae were collected and k_aVFA was measured in all cows. On average, 13.8 (standard deviation: 3.8) papillae were collected each from the ventral, caudodorsal, and caudoventral rumen sacs per cow per day. The k_aVFA was measured by incubating a standardized buffer fluid (45 L), containing 120 mM VFA (60% acetic, 25% propionic, and 15% butyric acid) and Co-EDTA as fluid passage marker, in the evacuated and washed rumen. Treatment did not affect ap or pp DM and energy intakes or milk yield and composition. Treatment increased papillae surface area, which was 19 and 29% larger at 18 and 8 d ap compared with 28 d ap, respectively. Surface area increased, mainly due to an increase in papillae width. However, treatment did not increase k_aVFA at 18 and 8 d ap compared with 28 d ap. In the control group, no changes in papillae surface area or k_aVFA were observed during the dry period. In the treatment group, papillae surface area decreased between 8 d ap and 3 d pp, whereas no decrease was observed for control. From 3 to 45 d pp, papillae surface area and k_aVFA increased for all cows by approximately 50%, but the ap concentrate treatment did not affect k_aVFA pp. In conclusion, the efficacy of supplemental concentrate during the dry period to increase papillae surface area and k_aVFA in preparation for subsequent lactation is not supported by the present study. Current observations underline the importance of functional measurements in lieu of morphological measurements to assess changes in the adapting rumen wall.     

Technical note: An evaluation of technology-recorded rumination and feeding behaviors in dairy heifers

Precision dairy monitoring technologies have become increasingly popular for recording rumination and feeding behaviors in dairy cattle. The objective of this study was to validate the rumination and feeding time functions of the CowManager SensOor (Agis, Harmelen, the Netherlands) against visual observation in dairy heifers. The study took place over a 44-d period beginning June 1, 2016. Holstein heifers equipped with CowManager SensOor tags attached according to manufacturer specifications (n = 49) were split into 2 groups based on age, diet, and housing type. Group 1 heifers (n = 24) were calves (mean ± SD) 2.0 ± 2.7 mo in age, fed hay and calf starter, and housed on a straw-bedded pack. Group 2 heifers (n = 25) were 17.0 ± 1.3 mo in age, fed a TMR, confirmed pregnant, and housed in freestalls. Visual observation shifts occurred at 1500, 1700, 1900, and 2100 h. Each heifer was observed for 2 hour-long periods, with both observation periods occurring on the same day. Visual observations were collected using a synchronized watch, and “start” and “stop” times were recorded for each rumination and feeding event. For correlations, data from CowManager SensOor tags and observations were averaged, so a single 1-h observation was provided per animal, reducing the potential for confounding repeated measures being collected for each animal. Concordance correlations (CCC; epiR package; R Foundation for Statistical Computing, Vienna, Austria) and Pearson correlations (r; CORR procedure; SAS Institute Inc., Cary, NC) were used to calculate association between visual observations and technology-recorded behaviors. Visually observed rumination time was correlated with the CowManager SensOor (r = 0.63, CCC = 0.55). Visually observed feeding time was also correlated with the CowManager SensOor (r = 0.88, CCC = 0.72). The difference between technology-recorded data and visual observation was treated as the dependent variable in a mixed linear model (MIXED procedure of SAS). Time of day, age in months, and group were treated as fixed effects. Individual heifers were treated as random and repeated effects. The effects of time of day, age, and group on rumination and feeding times were not significant. The CowManager SensOor was more effective at recording feeding behavior than rumination behavior in dairy heifers. The CowManager SensOor can be used to provide relatively accurate measures of feeding time in heifers, but its rumination time function should be used with caution.     

Short communication: Limit feeding dairy heifers: effect of feed bunk space and provision of a low-nutritive feedstuff

The objectives of this study were to examine the behavioral effects of providing limit-fed dairy heifers an increased amount of feed bunk space compared with recommended feed bunk allowance, and to determine if the effects of provision of extra bunk space would be comparable to those seen when limit-fed heifers are provided a low-nutritive feedstuff. Twelve Holstein dairy heifers (381.1 ± 44.8 d of age, 417.3 ± 47.9 kg), divided into groups of 4, were exposed to each of 3 treatments using a 3 × 3 Latin square design with 7-d periods. The treatments were (1) 0.68 m of feed bunk space/heifer (TMR-0.68), (2) 0.34 m of feed bunk space/heifer (TMR-0.34), and (3) 0.34 m of feed bunk space/heifer with an additional 0.34 m of feed bunk space available for free-choice straw (TMR-S). The total mixed ration was fed once daily at a restricted level (1.83% of body weight) and contained (dry matter basis) 19.9% alfalfa/grass haylage, 20.1% corn silage, 49.6% high-moisture corn, and 10.4% protein supplement. Group dry matter intake (DMI) was recorded daily. Behavior at the feed bunk was recorded for the last 4 d of each treatment period. Due to the provision of straw, DMI was highest on the TMR-S treatment compared with the other treatments (9.4 vs. 7.8 kg/d). Heifers spent the most time feeding when on the TMR-S treatment (147.7 min/d), with no difference in feeding time between the limit-fed TMR treatments (64.5 min/d). Within the TMR-S treatment, feeding time on the straw was 76.9 min/d; thus, the rate of consumption of only the TMR was similar across all treatments. Unrewarded time at the feed bunk (when no feed was present) did not differ between treatments. Heifers did not differ in competitive behavior when on the limit-fed TMR treatments (13.1 displacements/heifer per day). However, while on the TMR-S treatment, heifers displaced each other more frequently (23.8 displacements/heifer per day) than while on the other 2 treatments. Overall, results suggest that neither increased feed bunk space nor provision of straw will reduce competition for, or slow consumption rates of, a limit-fed TMR. The provision of straw alongside a limit-fed TMR did increase DMI, which would contribute to further rumen fill, and allowed heifers to increase their time spent feeding throughout the day.