Short communication: Rumination and feeding behavior before and after calving in dairy cows

The objectives of the current study were to describe changes in rumination and feeding behavior around calving. Rumination time, feeding time, and dry matter intake were monitored in 11 freestall-housed cows from 96 h before to 48 h after calving. Data were summarized in 2-h and 24-h periods, adjusting for calving time. Differences between baseline (96 to 24 h before calving) and subsequent 24-h periods were evaluated. Compared with baseline, cows spent, on average, 63 ± 30 min/24 h less time ruminating and 66 ± 16 min/24 h less time feeding in the 24-h period before calving. These behaviors continued to decline during the 24-h period after calving when, compared with baseline, time spent ruminating decreased on average by 133 ± 35 min/24 h and time spent feeding decreased by 82 ± 18 min/24 h. Dry matter intake tended to decrease by 3.8 ± 1.9 kg in the 24-h period before calving but returned to baseline values in the 24-h following calving. Rumination time and time spent feeding started to decline approximately 4 and 8 h before calving, respectively, and increased in the 4 to 6 h following calving. Rumination time and time spent feeding show promise as tools to identify cows close to calving.     

Short communication: Repeatability of measures of rectal temperature in dairy cows

Although taking body temperature by rectal thermometer is the method most commonly used to identify sick cows in the postpartum period, no data on the repeatability of this measure are available. The overall objective of this study was to evaluate variability of rectal temperatures in dairy cows considering different factors (intra- and interinvestigator repeatability, different thermometers, penetration depth into the rectum, and defecation). High coefficients of correlation (r = 0.98) and small differences between values of rectal temperatures (observer A = 39.3 ± 1.0°C and observer B = 39.4 ± 1.0°C) provide evidence that rectal temperature was a repeatable measure in dairy cows. Testing was carried out using 4 different digital thermometers: GLA M750 (GLA Agricultural Electronics, San Luis Obispo, CA), MTI8101 (SES Scala Electronics, Stahnsdorf, Germany), MT1831 (Microlife AG, Widnau, Switzerland) and Domotherm TH1 (Uebe Medical GmbH, Wertheim, Germany). Thermometers were inserted into the rectum to a certain depth (GLA M750 and MTI8101 = 11.5 cm; MT1831 = 8.4 cm; Domotherm TH1 = 7.7 cm) and a measure was finished when a visual or acoustic signal was emitted by the thermometer. The measures could be influenced by the procedure itself (up to 0.5°C), type of thermometer (up to 0.3°C), and the penetration depth (11.5 cm or 6.0 cm in one of the experiments) into the rectum (up to 0.4°C difference between a penetration depth of 11.5 cm and 6.0 cm in one of the experiments). Differences in rectal temperature before and after defecation were minor (<0.1°C). These results indicate that some care is required in generalizing rectal measures of body temperature.     

Short communication: Factors affecting hair cortisol concentrations in lactating dairy cows

Cortisol has long been used as a marker of the stress response in animals. Cortisol can be analyzed from different media, most notably from the blood, saliva, and feces; however, the collection of cortisol from some of these media requires invasive procedures or excessive handling of the animals. Furthermore, it is not possible to capture long-term increases in circulating concentrations of cortisol from the blood, saliva, or feces. Hair cortisol has been found to be a reliable alternative for measuring chronic stress. With this emerging measure, appropriate sampling methodology must be developed and validated. The aim of this study was to determine the effects of hair color, sampling location, and processing method on cortisol concentrations in hair from lactating black and white Holstein cows (n = 18). Furthermore, we aimed to measure the hair growth rates at different body locations (n = 12) and test hair cortisol levels when resampled over short intervals (n = 37). Both black- and white-colored hair was collected from the shoulder, top line, hip, and tail switch of Holsteins; due to breed characteristics only white hair was harvested from the tail switch. All samples were cleaned with water and isopropanol, and then ground in a ball mill or finely cut with scissors once dry. Cortisol was extracted with methanol before being measured using a commercially available ELISA kit. Concentrations of cortisol were greater in white than in black hair (7.8 ± 1.1 vs. 3.8 ± 1.1 pg/mg). When only white samples were analyzed, hair from the tail switch had more cortisol than hair from the shoulder (11.0 ± 1.2 vs. 6.2 ± 1.2 pg/mg), whereas no difference was found when compared with the hip and top line. Samples ground with a ball mill had greater concentrations of cortisol extracted than those minced with scissors (10.4 ± 1.2 vs. 4.7 ± 1.2 pg/mg). The growth rate of hair was significantly greater at the tail switch compared with the hip and shoulder (0.51 ± 0.05 vs. 0.04 ± 0.05 vs. 0.03 ± 0.05 mm/d). When hair was collected every 3 wk after calving, a tendency was detected for multiparous cows to have greater concentrations of hair cortisol and significantly greater concentrations of cortisol on d 0 and 21 after calving compared with d 42, 84, and 126. In Holsteins, the hair on the tail switch is always white, grows more rapidly than other sites, and is sensitive enough to capture changes in cortisol over intervals as short as 3 wk, making it the ideal location for measuring hair cortisol.     

Short communication: Calving site selection of multiparous,group-housed dairy cows is influenced by site of a previous calving

A calving cow and her newborn calf appear to have an attracting effect on periparturient cows, which may potentially influence the functionality of future motivation-based calving pen designs. In this pilot study we examined whether calving site selection of group-housed Holstein dairy cows was affected by the site of a previous calving. Ten multiparous cows moved to 1 of 2 group pens 11 (range = 4–27) d before calving were included. Each pen consisted of an open area (9 × 9 m) connected to 6 secluded areas (4.5 × 3 m each), where cows could move freely between all areas. Time of calving, location of the breaking of the amniotic sac, as well as the place of birth were recorded. In all but 1 case cows calved within a distance of 1 cow length from where the previous calving took place, suggesting that the cows did not select calving site at random. These preliminary observations indicate that choice of calving site may be affected by the site of a previous calving, potentially explained by the presence of amniotic fluids.     

Short communication: Automatic washing of hooves can help control digital dermatitis in dairy cows

The objectives of this study were to develop and test a system for automatic washing of the hooves of dairy cows and to evaluate the effect of frequent automatic washing on the prevalence of digital dermatitis (DD). An automatic hoof washer was developed in an experimental dairy herd and tested in 6 commercial dairy herds in 2 experiments (1 and 2). In the experimental herd, automatic hoof washing resulted in cleaner hooves. In experiments 1 and 2, cows were washed after each milking on the left side only, leaving the right side unwashed as a within-cow control. In experiment 1, hooves were washed with a water and 0.4% soap solution. In experiment 2, hooves were washed with water only. In each experiment, DD was scored in a hoof-trimming chute approximately 60 d after the start of hoof washing. Data were analyzed using a generalized linear mixed model. The outcome was the DD status of each leg (DD positive or DD negative). Herd and cow within herd were included as random effects, and treatment (washing or control) was included as a fixed effect. The statistical analyses showed that the odds ratio of having DD was 1.48 in the control leg compared with the washed leg in experiment 1. In experiment 2, the odds ratio of having DD was 1.27 in the control leg compared with the washed leg. We concluded that automatic washing of hooves with water and soap can help decrease the prevalence of DD in commercial dairy herds.     

Flooring in front of the feed bunk affects feeding behavior and use of freestalls by dairy cows

In 2 experiments we assessed how preferences, time budgets, and feeding behavior of dairy cows change in response to flooring surfaces in front of the feed bunk. In Experiment 1, 12 nonlactating dairy cattle were individually housed with access to 2 standing platforms filled with either concrete or sawdust. In Experiment 2, 24 nonlactating dairy cattle were given access to either concrete or Animat rubber flooring in front of the feed bunk. In Experiment 1, cows preferred the sawdust to the concrete flooring. In both experiments, cows provided with a softer floor in front of the feed bunk spent more time standing near the feed bunk without eating (Experiment 1: 67 vs. 40 min/d on sawdust vs. concrete, respectively, SEM = 5.6 min/d; Experiment 2: 176 vs. 115 min/d on Animat vs. concrete, respectively, SEM = 20.5 min/d) compared with when they were kept on concrete. The increased time spent at the feed bunk was due to a combination of more frequent eating and standing bouts, indicating that cows were more willing to move on nonconcrete flooring. Total time spent eating was significantly greater on the softer floor in Experiment 2, but not in Experiment 1 (Exp. 1: 289 vs. 275 min/d on sawdust and concrete, respectively, SEM = 7.3 min/d; Exp. 2: 330 vs. 289 min/d on Animat and concrete, respectively, SEM = 15.4), although feed intake was increased on the sawdust treatment in Experiment 1. Cows spent significantly more time lying in the feed alley when the flooring was rubber (219 vs. 53 min/d on Animat and concrete, SEM = 53.6 min/d), perhaps because the lying area in Experiment 2 was inadequate. In conclusion, cows prefer to stand on softer flooring in front of the feed bunk, and are more willing to move on and spend more time standing in front of the feed bunk when provided with softer flooring. These results indicate that cows find softer flooring surfaces more comfortable to stand on than concrete, and highlight the importance of evaluating the comfort of the entire facility.     

Short communication: Heritability of milk fatty acid composition and stearoyl-CoA desaturase indices in dairy cows

Activity of stearoyl-CoA desaturase (SCD) in the mammary gland is important for determining the relative proportions of saturated and monounsaturated fatty acids in milk and the concentration of the conjugated linoleic acid isomer rumenic acid (RA; cis-9,trans-11 18:2). Previous studies identified a large degree of between-cow variation in SCD activity, which was consistent across diets and suggests a genetic influence. The objectives of this study were to quantify genetic and phenotypic variations in fatty acid concentrations and SCD indices in milk fat and to estimate their heritabilities in a population of United Kingdom dairy cows. Milk samples were collected from 2,408 daughters of 597 Holstein-Friesian sires on 325 commercial farms for determination of fatty acid profiles. Indices of SCD activity were calculated by expressing each SCD product (cis-9 14:1, cis-9 16:1, cis-9 18:1, and RA) as a proportion of the precursor plus product [e.g., SCDI₁₄ = cis-9 14:1/(14:0 + cis-9 14:1)]. For individual fatty acids, phenotypic variance was considerably greater than additive genetic variance, resulting in small and nonsignificant heritability estimates (± standard error) for all except 6:0 (h² = 0.27 ± 0.10), 8:0 (h² = 0.27 ± 0.09), 12:0 (h² = 0.13 ± 0.07), cis-9 14:1 (h² = 0.28 ± 0.10), and cis-9 18:1 (h² = 0.12 ± 0.07). Heritability estimates of desaturase indices were significant for SCDI₁₄ (h² = 0.38 ± 0.11), SCDI₁₈ (h² = 0.19 ± 0.09), and SCDI_RA (h² = 0.21 ± 0.09), but not for SCDI₁₆ (h² = 0.05 ± 0.06). This study provides evidence that additive effects are responsible for a significant proportion of the phenotypic variation in SCD activity in dairy cows. It is concluded that because heritability of desaturase indices is moderate and significant in many cases, these indices could be investigated further for use in future breeding programs to increase concentrations of monounsaturated fatty acids and RA while decreasing concentrations of saturated fatty acids in milk fat.     

Short communication: Circulating and milk adiponectin change differently during energy deficiency at different stages of lactation in dairy cows

Adiponectin, one of the most abundant adipokines in circulation, is known for its role in regulation of body metabolism. The aim of this study was to evaluate the effects of a negative energy balance (NEB) at 2 stages of lactation (lactational NEB at the onset of lactation and an induced NEB by feed restriction near 100 d of lactation) on circulating adiponectin concentrations. We also investigated the effect of feed restriction on adiponectin concentrations in milk and the relationships of blood and milk adiponectin with selected plasma or milk variables and with measures of body condition. Plasma adiponectin was measured in 50 multiparous Holstein dairy cows throughout 3 experimental periods [i.e., period 1 = 3 wk antepartum up to 12 wk postpartum, period 2 = 3 wk of feed restriction starting at around 100 d in milk with a control (n = 25) and feed-restricted group (50% of energy requirements; n = 25), and period 3 = subsequent realimentation period for 8 wk]. Milk adiponectin was investigated among 21 multiparous cows at wk 2 and wk 12 of period 1 and wk 2 of period 2. Adiponectin concentrations in plasma and skim milk were measured using an in-house ELISA specific for bovine adiponectin. Major changes in circulating adiponectin concentrations were observed during the periparturient period, whereas energy deficiency during established lactation at around 100 d in milk and subsequent refeeding did not affect plasma adiponectin. Together with lower adiponectin concentrations in milk (µg/mL), the reduction in milk yield led to decreased adiponectin secretion via milk (mg/d) at the second week of feed restriction. Irrespective of time and treatment, milk adiponectin represented about 0.002% of total milk protein. Mean adiponectin concentrations in milk (0.61 ± 0.03 µg/mL) were about 92% lower than the mean plasma adiponectin concentrations (32.1 ± 1.0 µg/mL). The proportion of the steady-state plasma adiponectin pool secreted daily via milk was 2.7%. In view of the similar extent of NEB in both periods of energy deficiency, decreasing adiponectin concentrations seems important for accomplishing the adaptation to the rapidly increasing metabolic rates in early lactation, whereas the lipolytic reaction toward feed restriction-induced NEB during established lactation seems to occur largely independent of changes in circulating adiponectin.     

Short communication: Effects of dietary nonstructural carbohydrates pre- and postpartum on reproduction of grazing dairy cows

The working hypothesis was that postpartum anovulatory intervals (PPAI) of grazing dairy cows are shortened by inclusion of concentrates that increase the nonstructural carbohydrate content of the transition diet. Dietary treatments were arranged as a 2 × 2 factorial, with 68 multiparous cows assigned to isoenergetic diets (114 MJ of metabolizable energy/cow per day) of pasture and pasture silage (PreP) or pasture and pasture silage supplemented with 3 kg of dry matter/cow per day a corn- and barley-based concentrate for 36 d prepartum (PreC). After calving, cows within each prepartum diet group were managed on isoenergetic diets (179 MJ of metabolizable energy/cow per day) of either pasture and pasture silage (PostP) or pasture and pasture silage supplemented with 5 kg of dry matter/cow per day a corn- and barley-based concentrate (PostC) for at least 35 d and until reestablishment of ovulatory cycles. Relative to day of calving (d 0), blood samples were collected at least weekly from d −28 to 35 and milk samples were collected twice weekly for progesterone determination to diagnose ovulatory status. The main variable of interest was PPAI, defined as the interval between calving and the first detected increase in milk progesterone (>3 ng/mL), followed by a pattern of progesterone concentrations consistent with onset of an ovulatory cycle. Subsequent mating records, pregnancy testing, and recalving data were also examined. Prepartum diet did not affect reproduction. The PPAI was 8 d shorter and the 6-wk pregnancy rate was 17% greater in PostC cows compared with PostP cows. Measured indicators of metabolic state and energy balance were poorly related to PPAI. The results support the existence of nutritional signals associated with nonstructural carbohydrates in the postpartum diet, independent of energy balance; these signals benefit the physiological mechanisms underlying the timing of first ovulation and possibly subsequent breeding performance.     

Short communication: Lameness impairs feeding behavior of dairy cows

The automated, reliable, and early detection of lameness is an important aim for the future development of modern dairy operations. One promising indicator of lameness is a change in the feeding behavior of a cow. In this study, the associations between feeding behavior and lameness were evaluated. A herd of 50 cows was investigated during the winter season in a freestall barn. Feeding behavior, feed intake, milk yield, and body weight were monitored using electronic feeding troughs and an automated milking system. Gait scoring every second week was used as a measure of lameness. To analyze the effect of lameness on feeding behavior and milk yield, linear mixed models were used. Cows with more severe lameness spent less time feeding per day (104 ± 4, 101 ± 4, and 91 ± 4 min/d for lameness scores 2, 3, and 4, respectively). An interaction between parity and lameness score was detected, with severely lame primiparous cows spending the least time feeding. Severely lame cows fed faster; however, their body weights were lower than for less-lame cows. Increase in lactation stage was associated with longer daily feeding time, longer duration of feeding bouts, and lower feeding rate. Worsening of gait was associated with lower silage intake and less time spent feeding even before severe lameness was scored. The results indicate that lameness is associated with changes in feeding behavior and that such changes could be considered in the future development of remote monitoring systems. It should also be noted that impaired feeding behavior along with lameness can put the welfare of especially early lactating primiparous cows at risk.     

Validity of prepartum changes in vaginal and rectal temperature to predict calving in dairy cows

The prevalence of dystocia is high in many dairy herds and is associated with stillbirth and negative effects for the cow. An accurate predictor of calving would enable supervision of cows more precisely to a relevant time interval so that obstetrical assistance can be provided in a timely manner. This might help to decrease calf mortality rate. Evidence exists that cows exhibit a decrease in body temperature before the onset of calving. The performance of a decrease in body temperature as a test to predict the onset of calving in dairy cows has not been investigated. The objective was to investigate test criteria of a decrease in vaginal and rectal temperature as predictors of calving in dairy cows. In 3 experiments, temperature loggers (Minilog 8, Vemco Ltd., Halifax, Canada) were inserted into the vagina of cows before calving (n = 85), and rectal temperatures were measured twice daily in 55 of these cows. Vaginal temperatures were 0.2 to 0.3°C and 0.6 to 0.7°C lower on the day of calving compared with 24 and 48 h before calving, respectively. Rectal temperatures were 0.3 to 0.5°C and 0.4 to 0.6°C lower on the day of calving compared with 24 and 48 h before calving, respectively. Vaginal temperatures exhibited a diurnal rhythm during the 120 h before calving, which continued on a lower level during the 48 h preceding parturition. In the 3 experiments, a decrease in vaginal temperature of ≥0.3°C over 24 h could predict calving within 24 h, with sensitivity ranging from 62 to 71% and specificity ranging from 81 to 87%. Similarly, a decrease in rectal temperature measured at 0730 h of ≥0.3°C could predict calving within 24 h, with sensitivity from 44 to 69% and specificity from 86 to 88%. Although dairy cows exhibit a distinctive decrease in vaginal and rectal temperatures commencing approximately 48 h before calving, detecting this decrease does not determine the onset of calving precisely. Nevertheless, it can provide valuable information in addition to the traditional signs (i.e., relaxation of the sacrosciatic ligament) that calving is imminent.     

Short communication: Serum osteoprotegerin concentrations in periparturient dairy cows

Dairy cows experience hypocalcemia at the onset of lactation; however, the contribution of bone metabolism to circulating Ca concentrations during the periparturient period is not well understood. Osteoprotegerin (OPG) protects against loss of skeletal mass by regulating osteoclastogenesis. We previously reported that the bone resorption increased around parturition in dairy cows from the perspective of bone markers in blood. The aim of this study was to explore osteoclastic bone resorption in periparturient dairy cows by measuring changes in serum OPG concentrations around calving. The OPG concentrations were evaluated in primiparous (n = 9) and multiparous (n = 9) cows at 21 d precalving and over 5 d after calving. Based on mixed model analyses, the multiparous cows had a higher serum OPG concentration than primiparous cows at precalving and exhibited a significant decline in serum OPG and Ca concentrations after calving. In contrast to multiparous cows, primiparous cows did not exhibit these changes. Therefore, we hypothesized that multiparous cows preserve their bone mineral content during late pregnancy and activate the osteoclastic bone resorption after calving. Based on our serum OPG data, we identified the different periparturient osteoclastic bone resorption patterns in healthy primiparous and multiparous dairy cows.     

Short communication: Changes in heart rate variability of dairy cows during conventional milking with nonvoluntary exit

Heart rate variability (HRV), as a physiological measure of animal welfare, was investigated in 36 cows milked in a parallel milking parlor with nonvoluntary exit. Heart rate variability parameters measured during the morning resting (baseline period) were compared with those measured during different stages of the entire milking process. No differences were found in HRV parameters between the baseline period, preparation, and main milking. A considerable reduction in vagal activity was detected during the movement of the cows to the milking parlor (driving) and while cows were in the holding area. The parasympathetic measures of HRV decreased whereas the sympatho-vagal balance increased compared with baseline. The same pattern was observed regarding the stage between removing the teat cups and leaving the milking parlor (waiting). No differences in any sympathetic measures were observed between the baseline period and any of the milking stages. These findings indicate that the milking process itself (preparation and main milking) is not stressful for cows. Decreased parasympathetic activity during driving might be the result of the physical activity of the cows, whereas waiting in the holding area and in the milking stall after milking caused stress for animals.     

Behavioral changes in dairy cows with metritis in seasonal calving pasture-based dairy system

The aims of this study were to determine changes in lying and rumination behavior of transition dairy cows that were healthy or affected by metritis during the autumn and spring calving season in a temperate climate and determine the effect of some weather variables (precipitation and heat stress) on these behaviors. A total of 103 multiparous cows were monitored during the autumn (February to April) and spring calving season (July to October) from 10 d before to 10 d after calving. Cows were chosen retrospectively by diagnosis of metritis [autumn season, (n = 11); spring season, (n = 13)] or as healthy [autumn season, (n = 25); spring season, (n = 25)] based on vaginal discharge characteristics evaluated during the first 10 days in milk. In all animals, electronic data loggers recorded lying (Hobo Pendant G Acceleration, Onset Computer Corp.) and rumination behavior (Hi-Tag rumination monitoring system, SCR Engineers Ltd.) during the study period. We included precipitation level (>1 mm/d = with rain, and ≤1 mm/d = without rain) and heat stress [no heat stress = temperature-humidity index (THI) < 68 vs. heat stress = THI ≥ 68] as weather factors that may have affected lying and rumination behavior during the spring and autumn season in a temperate climate, respectively. Metritis during the spring calving season was associated only with longer lying times (≥1.3 h/d) after calving. During the autumn calving season cows with metritis lay down longer the day of calving (~2.1 h/d) and had fewer lying bouts of longer duration during the prepartum period compared with healthy cows. Rumination time did not differ by health status during the spring calving season, whereas cows with metritis during autumn ruminated 30, 21, and 24 min/d less than healthy cows during the prepartum, calving, and postpartum period, respectively. Precipitation and heat stress were associated with decreased daily lying and rumination time in sick cows. Our results indicate that differences in lying and rumination behavior depended on the metritis status, and support the idea that weather factors such as rainfall or heat stress requires to be considered in analyses of transition cow behavior in seasonal calving pasture-based dairy systems.     

Effects of bedding quality on lying behavior of dairy cows

Cows prefer to spend more time lying down in free stalls with more bedding, but no research to date has addressed the effects of bedding quality. Bedding in stalls often becomes wet either from exposure to the elements or from feces and urine. The aim of this study was to test the effect of wet bedding on stall preference and use. Four groups of 6 nonlactating Holstein cows were housed in free stalls bedded daily with approximately 0.1 m of fresh sawdust. Following a 5-d adaptation period, each group of cows was tested sequentially with access to stalls with either dry or wet sawdust bedding (86.4 ± 2.1 vs. 26.5 ± 2.1% dry matter), each for 2 d. These no-choice phases were followed by a 2-d free-choice phase during which cows had simultaneous access to stalls containing either wet or dry bedding. Stall usage was assessed by using 24-h video recordings scanned at 10-min intervals, and responses were analyzed by using a mixed model, with group (n = 4) as the observational unit. The minimum and maximum environmental temperatures during the experiment were 3.4 ± 2.2 and 6.8 ± 2.5°C, respectively. When cows had access only to stalls with wet bedding, they spent 8.8 ± 0.8 h/d lying down, which increased to 13.8 ± 0.8 h/d when stalls with dry bedding were provided. Cows spent more time standing with their front 2 hooves in the stall when provided with wet vs. dry bedding (92 ± 10 vs. 32 ± 10 min/d). During the free-choice phase, all cows spent more time lying down in the dry stalls, spending 12.5 ± 0.3 h/d in the dry stalls vs. 0.9 ± 0.3 h/ d in stalls with wet bedding. In conclusion, dairy cows show a clear preference for a dry lying surface, and they spend much more time standing outside the stall when only wet bedding is available.     

Short communication: Herd-level reproductive performance and its relationship with lameness and leg injuries in freestall dairy herds in the northeastern United States

The objectives of this study were to describe herd-level reproductive outcomes and their associations with the prevalence of lameness, hock injuries and knee injuries in freestall dairy herds in the northeastern United States. Five reproductive outcomes (calving to conception interval, CCI; calving interval, CI; conception risk at the first artificial insemination, CR1; insemination rate, IR; and pregnancy rate, PR) were measured from Dairy Comp 305 (Valley Agricultural Software, Tulare, CA) for a 12-mo period for all multiparous cows in each of the 53 herds assessed. The prevalence of lameness, hock injuries, and knee injuries was assessed in 1 high-producing group. The means (± standard deviation) for the 5 reproductive outcomes were as follows: CCI = 128 ± 10 d, CI = 404 ± 10 d, CR1 = 36 ± 5%, IR = 60 ± 7%, and PR = 20 ± 3%. The average prevalence of clinical lameness, hock injuries, and knee injuries were 45 ± 20%, 58 ± 31%, and 16 ± 15%, respectively. Univariable associations between the reproductive outcomes and the prevalence of lameness and leg injuries were tested and significant predictors were submitted to a model that controlled for the confounding effects of herd size, 305-d mature equivalent milk production of the high-producing group, and use of deep bedding. A higher prevalence of lameness was associated with poorer reproductive performance, although the relationships were weak: herds with a higher prevalence of lameness had longer average CCI (slope estimate = 0.16 ± 0.07; R² = 0.09) and CI (slope estimate = 0.14 ± 0.07; R² = 0.07). These results indicate that management to reduce lameness may improve reproductive performance.     

Short communication: Plasma concentration of glucose-dependent insulinotropic polypeptide may regulate milk energy production in lactating dairy cows

In dairy cows, an increase in plasma concentration of glucose-dependent insulinotropic polypeptide (GIP) is associated with an increase in metabolizable energy intake, but the role of GIP in energy partitioning of dairy cattle is not certain. The objective of this study was to examine the relationship between plasma GIP concentrations and energy partitioning toward milk production. Four mid-lactation, primiparous, rumen-fistulated Holstein-Friesian cows were fed a control diet of 55% forage and 45% concentrate [dry matter (DM) basis] in a 4 × 4 Latin square design with 4-wk periods. The 4 treatments were (1) control diet fed at 1000 and 1600 h, and (2) once-daily (1000 h) feeding, (3) twice-daily (1000 and 1600 h) feeding, and (4) 4 times/d (1000, 1600, 2200 and 0400 h) feeding of the control diet plus 1 dose (1.75 kg on a DM basis at 0955 h) into the rumen of supplemental vegetable proteins (Amino Green; SCA NuTec Ltd., Thirsk, UK). Measurements of respiratory exchange and energy balance were obtained over 4 d during the last week of each period while cows were housed in open-circuit respiration chambers. Blood was collected from the jugular vein every 30 min for 12 h, using indwelling catheters, starting at 0800 h on d 20 of each period. Plasma GIP concentration was measured in samples pooled over each 5 consecutive blood samplings. The relationships between plasma GIP, DM intake, heat production, respiratory quotient (RQ), milk yield, and milk energy output were analyzed using linear correlation procedures, with metabolizable intake as a partial variant. Plasma GIP concentration was not correlated with heat production, or milk yield, but was positively correlated with milk energy yield (correlation coefficient = 0.67) and negatively correlated with RQ (correlation coefficient = −0.72). The correlations between GIP with RQ and milk energy output do not imply causality, but support a role for GIP in the regulation of energy metabolism in dairy cows.     

Short communication: Added value of rumination time for the prediction of dry matter intake in lactating dairy cows

The objective of the current study was to quantify the change in the prediction of dry matter intake (DMI) resulting from the inclusion of rumination time (RT) in the 2001 National Research Council (NRC) DMI prediction model. Forty-one Holstein cows fed the same total mixed ration were involved in a 10-wk study. Individual DMI were measured daily. The accuracy and precision of the original NRC prediction model, based on body weight, fat-corrected milk, and week of lactation as independent variables, was compared with the accuracy and precision of the same model with RT as an additional independent variable. The RT estimate was significant in the model developed but had a low value (0.031 kg/h). Root mean square prediction errors were very similar in the 2 models (1.70 and 1.68 kg/d) as were the other indicators (R², linear bias, random error, and concordance correlation coefficient) selected to compare the models in this study. These results indicate no gain in DMI prediction precision or accuracy when RT is included in the NRC model.     

Individual and environmental factors associated with defecation while lying down in dairy cows

Cows typically defecate while standing. Freestalls are designed to position standing cows such that their feces fall into the alley. Cows sometimes defecate while lying down, increasing the risk that feces contaminate the stall surface. We conducted 2 studies investigating cow-level and environmental factors associated with defecating while recumbent. In experiment 1, we hypothesized that conditions making it more difficult for cows to stand up (including greater age, high body weight, pregnancy, and lameness) would increase the risk of this behavior. We followed 92 cows for 12 d, scanning stalls 5 times/d using live observation. Almost half (48%) of all cows defecated while recumbent at least once; cows that spent more time lying down and that were earlier in gestation were at highest risk. Weight, parity, age, and lameness were not associated with this behavior. In experiment 2, we tested how overstocking influenced the occurrence of defecating while recumbent. We predicted overstocking would increase the occurrence of this behavior, especially when cows were in stalls at more preferred locations. We recorded stall occupancy, displacement attempts, and defecating while recumbent in 4 groups of 36 cows tested at both 100% and 150% lying stall stocking densities for 2 nights each using a crossover design. Overstocking resulted in higher stall use and more displacements, but less lying and fewer perching events. We did not detect any relationship between use of specific stalls or competition and defecating while recumbent. Most recorded displacements were associated with perching. Increased time perching increased the likelihood of defecating while recumbent, perhaps because perching cows were less dominant or more reluctant to stand up once lying down in the stall. Overstocking did not increase defecating while recumbent, likely because cows spent less time lying down. Together, these results indicate that defecating while recumbent can be common, and points to some of the cow-level factors associated with this behavior.     

Short communication: Genetic relationships between the Holstein cow populations of three European dairy countries

The degree of relatedness was studied in 3 dairy cow populations from Great Britain (GBR), Italy (ITA), and Ireland (IRL) by using cows born from 2003 to 2006. Effective population size, inbreeding coefficient (F), and average relationship in the top and bottom 4,000 cows ranked on a profit index value (PIV) or milk yield evaluations were studied. Average inbreeding was approximately 2% in GBR and ITA, was 1% in IRL, but was slightly more than 2% when the joint pedigree was used. The average F for the joint population was 10 to 15% higher than estimates averaged across the 3 populations, reflecting the increased completeness of pedigree information in the joint pedigree. Effective population size in the joint pedigree was approximately 12% lower than estimates within the individual countries. The average genetic relationships for the top 4,000 PIV cows were not markedly different from those based on milk evaluation in GBR and ITA, but were approximately 2% lower in IRL. This was due to the use of an index with less weight on production traits in IRL compared with GBR and ITA. However, selection of the top 4,000 cows on PIV reduced the degree of relatedness across the 3 countries. The use of common sires accounted for most of the relatedness across the 3 countries, more than did the use of related sires or common foreign dams.