The degree of visual cover and location of birth fluids affect dairy cows' choice of calving site

Under natural conditions, cows seek isolation and visual cover when calving becomes imminent, but the degree of visual cover necessary to provide an attractive calving site is not known. When calving indoors, preparturient cows are attracted to other cows' birth fluids, and this may influence their isolation seeking. Therefore, we aimed to investigate the effect of degree of visual cover of secluded areas and the location of birth fluids on dairy cows' calving site selection. One hundred twenty-four Danish Holstein cows were moved in groups of 8 to 12 to a group pen with access to 6 areas secluded by a barrier of either 3 m (wide barrier) or 1.5 m (narrow barrier). Sixty cows calved within 14 d of having been moved to the group pen and were included in the study. From 3 h before partition and until the cow and calf were removed from the pen within 3 h after parturition, the location and posture of cows were recorded, along with the location of where their birth fluids were discharged. In addition, location and posture of calves were recorded during and up to 3 h after calving. All data were collected from continuous video recordings. Continuous data for location and behavior were analyzed by mixed models, binary data were analyzed by chi-squared analysis, and location of calving relative to where the cow's own or alien birth fluids were discharged was analyzed using logistic regression models. Ten percent of the cows calved in a secluded area, with no effect of barrier width. However, before calving, cows with access to secluded areas with a wide barrier spent more time in a secluded area (22 vs. 7 min/3 h), and more cows were observed lying there (58 vs. 28%) than cows with access to secluded areas with a narrow barrier. Secluded areas with a wide barrier were used by more cows and calves during the first hour after calving (36 vs. 10%). Among the cows that entered a secluded area after calving, the latency to enter correlated with their calf's latency to enter, suggesting that the 2 sought seclusion together. Seventy-nine percent of the cows calved in proximity (within a 1.25-m radius) to their own or an alien cow's birth fluids. There was no effect of barrier width on the probability of calving in proximity to their own or alien birth fluids. However, the probability of calving in proximity to their own or alien birth fluids was higher than the probability of not doing so. The greater use of secluded areas with a 3-m-wide barrier before and after parturition suggests that these are preferred over areas with a 1.5-m-wide barrier. Only a few cows calved in a secluded area, and more research is needed to explore the environmental and social factors affecting parturient cows' use of designated calving areas. The majority of cows calved close to where their own or alien birth fluids were discharged, suggesting that cows are attracted to these before calving. This may have affected the use of secluded areas as calving sites.     

Spatial heterogeneity enhances and modulates excitability in a mathematical model of the myometrium

The muscular layer of the uterus (myometrium) undergoes profound changes in global excitability prior to parturition. Here, a mathematical model of the myocyte network is developed to investigate the hypothesis that spatial heterogeneity is essential to the transition from local to global excitation which the myometrium undergoes just prior to birth. Each myometrial smooth muscle cell is represented by an element with FitzHugh–Nagumo dynamics. The cells are coupled through resistors that represent gap junctions. Spatial heterogeneity is introduced by means of stochastic variation in coupling strengths, with parameters derived from physiological data. Numerical simulations indicate that even modest increases in the heterogeneity of the system can amplify the ability of locally applied stimuli to elicit global excitation. Moreover, in networks driven by a pacemaker cell, global oscillations of excitation are impeded in fully connected and strongly coupled networks. The ability of a locally stimulated cell or pacemaker cell to excite the network is shown to be strongly dependent on the local spatial correlation structure of the couplings. In summary, spatial heterogeneity is a key factor in enhancing and modulating global excitability.     

Effects of prepartum dietary calcium level on calcium and magnesium metabolism in periparturient dairy cows

The aim of this study was to investigate the effects of dietary Ca level (4.9, 9.3, and 13.6 g/kg of DM) on Ca and Mg homeostasis in dairy cows around parturition. Cows of the Swedish Red breed (n = 29) with no previous veterinary treatment for milk fever were divided into 3 groups, and each group was fed one of the different diets during the last 15 to 32 d of gestation. Calcium was added as ground limestone, and the Mg concentration was 1.8 g/kg of DM in all diets. After calving the cows were fed similar diets. Plasma was sampled twice per week until calving, and 6, 12, and 24 h, 2, 4, and 7 d after calving. Spot urine samples were collected twice weekly until calving and creatinine was used as a marker of daily urinary excretion. Fecal samples were collected 2 times per day for 5 d starting 2 wk before expected calving, and acid-insoluble ash was used as an indigestible marker to estimate digestibility. Apparent digestibility of Mg and daily Mg excretion in the urine were lower in the dry period for cows fed the highest Ca level. Plasma Mg concentration was lower on 2, 4, and 7 d after calving in cows fed the highest level of Ca. Treatment groups did not differ in plasma Ca concentration, parathyroid hormone concentration, or bone mobilization, evaluated using crosslinked carboxyterminal telopeptides of type I collagen (CTx) as a marker. Plasma Ca concentration decreased and plasma CTx concentration increased 6 h after calving. The apparent digestibility of Ca during the dry period was not affected by dietary Ca, but the cows fed 4.9 g Ca/kg of DM excreted 1.2 g of Ca/d in the urine, which was higher compared with 0.4 g/d and 0.6 g/d for the cows fed 9.3 g of Ca/kg of DM and 13.6 g of Ca/kg of DM, respectively. The results show that feeding 13.6 g of dietary Ca/kg of DM impaired the Mg absorption during the dry period, and resulted in decreased plasma Mg concentration after calving, but prepartum dietary Ca level did not affect plasma Ca, parathyroid hormone, or CTx concentrations.     

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.     

Experience-dependent cell survival in the maternal rat brain.

Postpartum maternal experience produces long-lasting changes in maternal behavior in the mother rat, which can be altered by early-life isolation. Postpartum experience also affects the regulation of adult neurogenesis in the neural circuit underlying maternal behavior, in a region-specific manner. Female rats were reared either with their mothers (MR) or in isolation in an artificial rearing (AR) paradigm. In adulthood, rats were mated and separated from their pups at birth. The following day, dams were injected with a mitotic marker and either allowed to interact with pups (maternal experience) or left alone. Results show that MR rats that acquire a later maternal experience show increases in cell survival in parts of the excitatory limb of the maternal neural network (bed nucleus of the stria terminalis and nucleus accumbens), but no changes in the inhibitory limb (amygdala). In comparison to AR inexperienced rats, AR maternally experienced rats show no increases in cell survival in the excitatory limb, but a striking reduction in cell survival in the inhibitory limb. The results suggest that early preweaning maternal isolation alters the structural plasticity that occurs following a postpartum maternal experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

The effect of hides and parity on behavior of periparturient dairy cows at pasture

Under natural conditions, most parturient cows seek visual cover or seclude themselves from the herd when calving becomes imminent. Studies on calving site selection of dairy cows housed indoors show that predominantly older and dominant cows calve in secluded areas. This study aimed to investigate whether cows distance themselves further from herd members under spacious outdoor conditions and whether artificial hides on a pasture motivate cows to seek visual isolation from the herd. One hundred eighty-two Danish Holstein cows were allocated to 1 of 13 groups of 14 cows according to expected calving date. In 2 paddocks (each 75 × 150 m), 5 zones (75 m × 30 m) were defined; zone 0 contained the feeding and shade area, and zone 4 bordered an area with trees. Weekly and according to calving date, a group of 14 cows was moved either to a paddock that had 12 hides distributed evenly throughout zones 1 to 4 (7 groups) or to a paddock without hides (6 groups). The hides were wooden structures (3.3 m long × 1.0 m wide × 1.2 m high) that the cows could hide behind. One hundred seven cows calved within 14 d of having been moved to the paddock, and 82 of these (38 primiparous and 44 multiparous), and their calves, were included in the study. From 3 h before until 3 h after calving, the location, posture, and behavior of cows were recorded continuously from video recordings. In addition, location, posture, and behavior of the calves were recorded for the first 3 h after birth. Continuous variables were analyzed by linear mixed effects models, whereas binary data were analyzed using mixed effects logistic regression. The presence of hides did not affect selection of calving location in the paddock, but more primiparous than multiparous cows calved in zone 4; that is, furthest away from the feeding area. Before calving, primiparous cows were more likely to be positioned in zone 4 and less likely to approach and contact herd members. After calving, primiparous cows and their calves tended to be more likely to be positioned in zone 4. The more cows present in the paddock, the less likely the cows were to isolate (i.e., be further than 30 m away from any other cow) at the time of calving. In addition, the more cows in the paddock when a calf was born, the less time these calves spent in a lying posture. The results show that primiparous cows move further away from herd members at calving than multiparous cows and suggest that primiparous cows prefer to isolate themselves through distance rather than seeking artificial cover. Contrary to expectation, the hides did not make more cows select a calving site away from the feeding area.     

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.     

Reduced levels of total leukocytes and neutrophils in Norwegian cattle selected for decreased mastitis incidence

Two groups of Norwegian Cattle showing significant genetic differences in clinical mastitis susceptibility were examined for hematological changes at three stages of lactation. Blood samples were taken from 91 healthy Norwegian Cattle cows and heifers belonging either to a high protein yield group or to a low clinical mastitis group and analyzed for hematological properties and serum cortisol levels at three stages of lactation. All animals were free of intramammary infections at the time of sampling. All cows had increased total white blood cells, neutrophils, and neutrophil/lymphocyte ratio as parturition approached, with peak levels at parturition. Cows selected for low clinical mastitis had lower levels of total white blood cells and neutrophils compared with cows selected for high protein yield throughout all three periods. The difference was significant prepartum. Cows from the low clinical mastitis group also had lower neutrophil/lymphocyte ratios and lower serum cortisol levels than those in the high protein yield group. A significant positive correlation was found between cortisol and total white blood cells and neutrophils, respectively. We conclude that selection for lower mastitis incidence in the low clinical mastitis group is associated with a significant decrease in total white blood cells and neutrophils in blood prepartum. Results from the present study, and the genetic difference in mastitis incidence observed in the groups, indicates that increased leukocyte mobilization at certain stages of lactation may be associated with increased susceptibility to mastitis.     

Denaverine hydrochloride and carbetocin increased welfare during and after parturition and enhanced subsequent fertility in cattle

The objectives of the current study were to investigate the influence of denaverine hydrochloride and carbetocin on softening and dilatation of the birth canal, the need for assistance during parturition, calf mortality, retention of fetal membranes, endometritis, and subsequent fertility. Altogether 200 animals (100 cows and 100 heifers) of the Simmental breed were divided into 2 groups: treatment (n = 100) and control (n = 100). Animals in the treatment group received denaverine hydrochloride and carbetocin (a maximum of twice for each, depending on the progression of labor) during delivery over a maximum of 4 waiting periods (30 min each), whereas control animals experienced the same waiting periods but received no treatment. The treatment protocol had a positive influence on the ease of calving and postpartum reproductive health. The treatment increased the number of animals with the birth canal dilated by more than 25 cm, and halved the need for any assistance at parturition. In addition, treatment decreased the occurrence of difficult calving, the need for episiotomy, the appearance of birth canal lesions, and clinical endometritis. The treatment protocol had an effect throughout the entire puerperal period, as treated animals conceived with fewer artificial inseminations (1.3 vs. 1.6 artificial inseminations/pregnancy) and sooner (67 vs. 78 d open) compared with control animals. Denaverine hydrochloride and carbetocin administered in combination during parturition affected the progression and ease of calving, and thus the welfare of cows in labor and subsequently. However, further studies are needed to confirm the findings and to establish best practices.