F.J.C.M. van Eerdenburg

Sexual activities and oestrus detection in lactating Holstein cows

Abstract During 6 weeks, the oestrus behaviour of all non-pregnant cows on two dairy farms was observed for periods lasting 30 min at 2 h intervals. Cows were housed in a free stall with cubicles and a concrete slatted floor. Pedometers were used to measure the physical activity of the cows throughout the oestrous cycle. Milk progesterone levels were used for confirmation of the oestrus date. Overall oestrus behaviour was less intense than described in previous studies. In only 37% of the oestruses was a standing heat observed. The behavioural oestrus symptoms were seen more frequently during the nocturnal period. Duration and intensity of the oestrus behaviour were influenced by the number of cows in oestrus. Pedometer readings were correlated with mounting other cows, resting with the chin on other cows, and total oestrus behaviour score. Two observations of 30 min per day would result in a detection efficiency of 74% and an accuracy of 100%. The time of observation during the day was found to be very important. Observations before milking gave a lower detection rate than observations after milking and feeding.

Non esterified fatty acids (NEFA) in dairy cattle. A review

Summary The objective of this report is to review the literature on elevated blood concentrations of nonesterified fatty acids (NEFA) before and after parturition in high‐yielding dairy cows. It highlights the factors that influence serum NEFA production and their circulation before and after parturition, such as adaptation for nutrient partitioning for fetal needs, onset of lactogenesis, stress of calving and numerous changes in physiological, metabolic, and endocrine status to accommodate parturition and lactogenesis. The role of NEFA in the liver and peripheral tissues and its toxic effects when in excess are discussed. The cows adaptive physiologic mechanisms to prevent or decrease excessive values of serum NEFA and preventive and therapeutic interventions to enhance these mechanisms are categorized as natural and artificial antidotes respectively. Feeding systems during the dry period and daily exercise or walking activity which may burn excessive NEFA through β‐oxidation in the muscles are considered as more useful antidotes to managing the NEFA metabolism. This will minimize accumulation of lipids in the liver during early lactation and alleviate the negative effects of plasma NEFA leading to more optimal metabolic health and productivity of dairy cows.

Detection of oestrus in dairy cows: A new approach to an old problem

Fertility indices, such as non-return rate and number of services per conception, have worsened significantly over the past few years. Because oestrus detection is one of the major factors influencing these indices, this study was performed to determine whether, how long, and at what time dairy cows show signs of oestrus in their behaviour. Two high producing herds with about 40 open cows were observed for 30 minutes every 2 hours for 6 weeks. The various signs of oestrus were recorded. The milk progesterone concentration was monitored daily to detect ovulation. A scale (Table 2) was composed according to the frequency of these symptoms during and between oestrous periods. This scale was used in order to determine which cows were in oestrus. Each oestrous symptom was given a score and the scores were summed for a 24-hour period. If a score of > 100 points was reached within a 24-h period, the cow was considered to be in oestrus. As used, the oestrus detection scale proved to be very convenient. Because standing oestrus was observed in only 37% of the oestri, this criterion had a very low sensitivity for oestrus detection. With the use of this scale and 12 observations per day, we reached a detection rate of 100%. If a more practical observation scheme would have been used (e.g. observing the herd twice daily, for 30 min) lower threshold values would have been obtained. This observation scheme resulted in a detection rate of 74% with no incorrect assessments.

RELATIONSHIP AMONG ESTRADIOL, CORTISOL AND INTENSITY OF ESTROUS BEHAVIOR IN DAIRY CATTLE

Economic profitability of a dairy farm is based, in part, on the calving interval of the cows. The optimal interval is 365 d. To achieve this, the cow needs to be pregnant within 85 d post partum. The first and most problematic step in this process is the determination of the optimal time for insemination, which is based on estrous behavior. The expression of estrous behavior, however, is at a low level in modem dairy herds, resulting in low detection rates and longer calving intervals. In the present study, a point scale was used to monitor postpartum, nonpregnant cows for estrous symptoms. Frequent blood samples were taken around estrus, and the cows were fit with pedometers to measure their activity. Correlations between the occurrence of symptoms of estrus and levels of estradiol and cortisol were then analyzed. Standing heat, the standard symptom of estrus, was observed in only 53% of the cows. A high correlation of 0.7 was found between estradiol concentration and estrous behavior. This was empasized by the fact that the estradiol level reached its highest level of 7.76 + 2.39 (SD) pg/mL at the same time as the highest behavior score. The highest pedometer readout lagged 8 h behind this moment. Cortisol levels did not exceed the physiological levels in rest situations but showed an increase at the time estrous behavior was at its maximum. The present study showed that standing heat is not the primary symptom for detecting estrus in cows. Pedometers are a useful aid but they have to be read several times a day. The high correlation between the visual symptoms of estrus and estradiol concentrations indicates that visual estrus detection is an efficient, reliable way to determine the right time for insemination.

Can we predict behaviour in pigs?: Searching for consistency in behaviour over time and across situations

Individual differences in animal behaviour could elucidate the differences in stress coping style, which have consequences for production, health and welfare. Therefore, individual behavioural differences in pigs and consistency of responses in different test situations were studied. If differences in behaviour reflect coping characteristics, then behaviour in one situation should predict behavioural reactions in other situations and at other times. In this study, a backtest was performed on 315 Great Yorkshire∗ Dutch Landrace piglets at 3, 10 and 17 days of age. On day 3, groups of approximately 10 piglets per sow were formed, based on escape behaviour in the first backtest (backtest score): high resisting (HR, all scores >3), low resisting (LR, all scores <3), miscellaneous (MISC, various scores between 0 and 10) or original (OR) litters to determine if group composition would influence coping behaviour. In weeks 5–7 and/or 10–12, a human approach test (HAT), a novel object test (NOT), and an open door test (ODT) were performed with all pigs simultaneously, in the home pen. Pearson correlation coefficients were calculated between the test results and a factor analysis was performed. Furthermore, data were analysed on pen level, and within MISC- and OR-pens on animal level, using multivariate linear models. Significant correlations were found between the backtests and between HAT, NOT and ODT. Backtest results on three ages loaded on the same factor, and HAT, NOT and ODT at one age also loaded on one factor. No differences were found in HAT, NOT and ODT for the different pens (HR, LR, MISC and OR). On animal level, animals with higher backtest scores also had higher HAT scores at 5–7 weeks (P<0.05) within the MISC-pens. At 10–12 weeks, no differences were found. This study suggests that there are consistencies in behaviour of pigs over time and across situations, so coping can be regarded as a trait variable. However, since correlations are well below one, we suggest that other factors such as time (development) and (test) situation may also play an important role in determining an individual’s behavioural reaction. The absence of correlations between backtest and the group tests is explained by the theory that these different tests measure different aspects of the coping style.

Cognitive disturbances in old dogs suffering from the canine counterpart of Alzheimer's disease

In geriatric dogs, Alzheimer-like behavior is frequently observed. This behavior has been classified by several authors using questionnaires and a correlation has been described between cognitive dysfunctions and Alzheimer-like pathology. In the present study, cognitive performance was correlated with brain pathology for 30 dogs of varying ages. Within these animals, two age-matched groups of old dogs with and without behavioral changes were compared. The behavioral changes were analyzed and scored with questionnaires and necropsy was performed to rule out any other cause for changed behavior. Measurements, (immuno)-histochemical staining and fluorescence microscopy were used to detect cortex atrophy, amyloid, rest-products of oxidative damage, demyelination and accumulations of macrophages in the brains of these dogs. Spearman rank correlation coefficients (r) were calculated and adjusted according to Bonferonni. In the whole group (young to very old dogs), the age of the animal showed a significant correlation with various behavioral changes (r = 0.7 to 0.9, P < 0.01). The dementia score correlated significantly (r = 0.6 to 0.8, P < 0.01) with all the brain lesions studied, except one, i.e. demyelination (r = -0.4, P > 0.05). These results suggest that a questionnaire can be used to diagnose Alzheimer-like changes in canine practice. Oxidative damage on a cellular and a nuclear level plays an important role in behavior changes.

A study on cow comfort and risk for lameness and mastitis in relation to different types of bedding materials

The aim was to obtain data regarding the effects of 4 freestall bedding materials (i.e., box compost, sand, horse manure, and foam mattresses) on cow comfort and risks for lameness and mastitis. The comfort of freestalls was measured by analyzing the way cows entered the stalls, the duration and smoothness of the descent movement, and the duration of the lying bout. The cleanliness of the cows was evaluated on 3 different body parts: (1) udder, (2) flank, and (3) lower rear legs, and the bacteriological counts of the bedding materials were determined. The combination of the cleanliness of the cows and the bacteriological count of the bedding material provided an estimate of the risk to which dairy cows are exposed in terms of intramammary infections. The results of the hock assessment revealed that the percentage of cows with healthy hocks was lower (20.5 ± 6.7), the percentage of cows with both damaged and swollen hocks was higher (26.8 ± 3.2), and the severity of the damaged hock was higher (2.32 ± 0.17) on farms using foam mattresses compared with deep litter materials [i.e., box compost (64.0 ± 10.4, 3.5 ± 4.7, 1.85 ± 0.23, respectively), sand (54.6 ± 8.2, 2.0 ± 2.8, 1.91 ± 0.09, respectively), and horse manure (54.6 ± 4.5, 5.5 ± 5.4, 1.85 ± 0.17, respectively)]. In addition, cows needed more time to lie down (140.2 ± 84.2s) on farms using foam mattresses compared with the deep litter materials sand and horse manure (sand: 50.1 ± 31.6s, horse manure: 32.9 ± 0.8s). Furthermore, the duration of the lying bout was shorter (47.9 ± 7.4 min) on farms using foam mattresses compared to sand (92.0 ± 12.9 min). These results indicate that deep litter materials provide a more comfortable lying surface compared with foam mattresses. The 3 deep litter bedding materials differed in relation to each other in terms of comfort and their estimate of risk to which cows were exposed in terms of intramammary infections [box compost: 17.8 cfu (1.0(4)) ± 19.4/g; sand: 1.2 cfu (1.0(4)) ± 1.6/g; horse manure: 110.5 cfu (1.0(4)) ± 86.3/g]. Box compost had a low gram-negative bacterial count compared with horse manure, and was associated with less hock injury compared with foam mattresses, but did not improve lying behavior (lying descent duration: 75.6 ± 38.8s, lying bout duration: 46.1 ± 18.5 min). Overall, sand provided the best results, with a comfortable lying surface and a low bacterial count.

Coping characteristics and performance in fattening pigs

Abstract Pigs vary in their individual behaviour in response to stress, and this coping behaviour can be measured with a backtest. In this test, a piglet is put on its back and escape attempts are counted during 1 min. Backtest results are linked to individual performance, and regrouping at 9 weeks of age on the basis of coping characteristics can influence production parameters. In the present study, piglets were cross-fostered at 3 days of age on the basis of backtest results, and pens with only active piglets (HR), with only reactive piglets (LR) and mixed pens were formed next to original litters. At 9 weeks animals were mixed and moved. The relation between backtest results and production performance was investigated. Cross-fostering induced a change in backtest results, resulting in approximately the same mean backtest results in each group and consequently on pen level no relations were found between initial coping behaviour and performance. Individual backtest results were linked to production parameters: active animals tended to grow faster and have a leaner carcass. If pig breeding companies would use the backtest to select the most active animals that are potentially the best performers, aggressive behaviour should also be considered (e.g. as part of the breeding goal), because of the link between activity and aggressive behaviour.

Sex differences in the distribution of estrogen receptors in the septal area and hypothalamus of the domestic pig (Sus scrofa)

Recently in the pig hypothalamus a vasopressin- and oxytocin-containing nucleus was identified which, like the supraoptic nucleus, becomes sexually dimorphic after puberty. Following the increase in circulating steroids at puberty, the vasopressin- and oxytocin-containing nucleus becomes twice as large in both males and females. In adulthood, the vasopressin- and oxytocin-containing nucleus of females is approximately twice as large as that in males. Because these alterations are possibly due to an influence of gonadal steroids, i.e. estrogens, the vasopressin- and oxytocin-containing nucleus cells were tested for the presence of estrogen receptors. In addition to the area of the vasopressin- and oxytocin-containing nucleus, the present study documented the distribution of estrogen receptors in the septal area and other parts of the hypothalamus of intact post-pubertal male and female pigs, by utilizing immunocytochemical methodology. Intense nuclear estrogen receptor staining was found in a number of areas, i.e. the medial preoptic area, the oxytocin-containing dorsomedial extension of the supraoptic nucleus, a possible homologue of the sexually dimorphic nucleus of the preoptic area, the median preoptic nucleus, the medial and lateral part of the bed nucleus of the stria terminalis, the ventromedial hypothalamus and the arcuate nucleus. In the ventral part of the lateral septum, the septohypothalamic nucleus, the nucleus subfornicalis and the stigmoid nucleus estrogen receptor immunoreactivity was less intense. Dorsolaterally of the vasopressin- and oxytocin-containing nucleus, estrogen receptor positive cells were observed, but the vasopressin- and oxytocin-containing nucleus itself lacked such receptors. In the magnocellular supraoptic nucleus and paraventricular nucleus no nuclear estrogen receptor staining was found. However, a weak cytoplasmic staining was present in all cells. There was a clear sex difference in the estrogen receptor-immunoreactive cell number in a possible homologue of the sexually dimorphic nucleus of the preoptic area. Compared to male pigs, in female pigs the number of cells showing estrogen receptor immunoreactivity in this area, which is known to be sexually dimorphic in various species, was twice as high. In other areas, such as the medial part of the bed nucleus of the stria terminalis, the medial preoptic area, the arcuate and ventromedial hypothalamic nucleus, a similar sex difference was found. In addition estrogen receptor immunoreactivity was generally more intense in females. No sex differences were noted in the overall distribution of estrogen receptor cells in the areas studied.(ABSTRACT TRUNCATED AT 400 WORDS)

Individual behavioural characteristics in pigs—influences of group composition but no differences in cortisol responses

To determine the effect of group composition on backtest (Bt) responses and to determine the predictive value of the Bt for the physiological stress response to weaning and mixing, 814 pigs were backtested at 3, 10 and 17 days of age. Twenty-nine percent of all pigs were cross-fostered at 3 days according to Bt responses and groups were formed of animals with high responses (HR) only, low responses (LR) only or mixed groups of animals with high, intermediate and low responses (MISC). Original litters (OR, no cross-fostering) were used as controls. Cortisol responses were measured in saliva after weaning at 4 weeks of age and after moving and mixing at 9 weeks of age. In HR groups, mean Bt responses decreased after cross-fostering while in LR groups, mean Bt scores increased. In both groups, Bt responses of individual animals before and after cross-fostering were not correlated. In MISC and OR groups, all Bt scores were correlated. Weaning and mixing caused a significant rise in cortisol in all animals while moving or weighing did not. No relations were found between Bt scores and cortisol levels. We conclude that Bt behaviour can change according to the social environment between 3 and 10 days. This could be intentional, to form a varied group, or it might be caused by a change in the hypothalamic-pituitary-adrenal (HPA) function due to social stress. At an older age, this ability is lost and common farm practises such as regrouping, weaning and mixing of piglets at ages >10 days might have a negative effect on the piglets.