Carola Fischer-Tenhagen

Measurement of fecal glucocorticoid metabolites and evaluation of udder characteristics to estimate stress after sudden dry-off in dairy cows with different milk yields.

Sudden dry-off is an established management practice in the dairy industry. But milk yield has been increasing continuously during the last decades. There is no information whether the dry-off procedure, which often results in swollen and firm udders, causes stress, particularly in high-producing dairy cows. Therefore, we evaluated the effect of a sudden dry-off on extramammary udder pressure and the concentration of fecal glucocorticoid metabolites (i.e., 11,17-dioxoandrostane, 11,17-DOA) as an indirect stress parameter. Measurements were carried out within the last week before dry-off and until 9d after dry-off considering 3 groups of milk yield (i.e., low: <15 kg/d, medium: 15-20 kg/d, and high: >20 kg/d). Udder pressure increased in all yield groups after dry-off, peaked at d 2 after dry-off and decreased afterwards. Pressures were highest in high-yielding cows and lowest in low-yielding cows. But only in high-yielding cows was udder pressure after dry-off higher than before dry-off. Baseline 11,17-DOA concentrations depended on milk yield. They were highest in low-yielding (121.7 ± 33.3 ng/g) and lowest in high-yielding cows (71.1 ± 30.0 ng/g). After dry-off, 11,17-DOA increased in all yield groups and peaked at d 3. Whereas in medium- and high-yielding cows 11,17-DOA levels differed significantly from their respective baseline during the whole 9-d measuring period, low-yielding cows showed elevated 11,17-DOA levels only on d 3 after dry-off. However, especially the increase in 11,17-DOA after dry-off between the 3 yield groups was considerably different. Mean 11,17-DOA increase from baseline to d 3 was highest in high-yielding cows (129.1%) and considerably lower in low-yielding cows (40.1%). The highest fecal 11,17-DOA concentrations were measured on d 3 after dry-off, indicating that the stress was most intense on d 2, which is due to an 18-h time lag; at about the same time, udder pressure peaked. Our results showed a negligible effect of a sudden dry-off on low-yielding cows. High-yielding cows, however, faced high extramammary pressures and increased glucocorticoid production. Considering animal welfare aspects, a review of the current dry-off strategies might be warranted.

Short communication: Ability of dogs to detect cows in estrus from sniffing saliva samples

Efficient estrus detection in high-producing dairy cows is a permanent challenge for successful reproductive performance. In former studies, dogs have been trained to identify estrus-specific odor in vaginal fluid, milk, urine, and blood samples under laboratory conditions with an accuracy of more than 80%. For on-farm utilization of estrus-detection dogs it would be beneficial in terms of hygiene and safety if dogs could identify cows from the feed alley. The objective of this proof of concept study was to test if dogs can be trained to detect estrus-specific scent in saliva of cows. Saliva samples were collected from cows in estrus and diestrus. Thirteen dogs of various breeds and both sexes were trained in this study. Five dogs had no experience in scent detection, whereas 8 dogs had been formerly trained for detection of narcotics or cancer. In the training and test situation, dogs had to detect 1 positive out of 4 samples. Dog training was based on positive reinforcement and dogs were rewarded with a clicker and food for indicating saliva samples of cows in estrus. A false indication was ignored and documented in the test situation. Dogs with and without prior training were trained for 1 and 5 d, respectively. For determining the accuracy of detection, the position of the positive sample was unknown to the dog handler, to avoid hidden cues to the dog. The overall percentage of correct positive indications was 57.6% (175/304), with a range from 40 (1 dog) to 75% (3 dogs). To our knowledge, this is the first indication that dogs are able to detect estrus-specific scent in saliva of cows.

Technical note: validating a dynamometer for noninvasive measuring of udder firmness in dairy cows.

Most measurements of udder pressure are based on devices connected to the gland cistern via cannulas. These devices are either inserted in the teat canal or surgically implanted into the udder tissue. In this study, instead of invasively measuring intramammary udder pressure, we measured the udder firmness noninvasively on the udder surface via a dynamometer. These are commonly used in food research to determine crispiness and firmness of fruits. The objective of this study was to validate a hand-held dynamometer for measuring udder firmness in dairy cows. Specifically we set out to determine inter-investigator repeatability considering potential confounders such as investigator, location, and cow. Through modifications in the standard operating procedure for the measurements, inter-investigator repeatability increased from correlation coefficient=0.80 (n=275) to correlation coefficient=0.94 (n=634). Measurements in different locations within the left hind quarter revealed a firmness gradient from the upper to the lower measuring point. Measurements between the 4 quarters within a cow displayed differences, except between both hind quarters. In 94.8% of the udders, firmness decreased due to milking. The correlation coefficient, however, between firmness changes and milk yield was low (r=0.42, n=153). Our data provide evidence that the dynamometer, although imperfect, does provide a reasonable measure of udder firmness and can be a useful tool in research related to animal health and welfare. However, a standardized operating protocol should be followed to minimize confounding by investigator, location, and quarter.

Efficacy of a treatment with hCG 4 days after AI to reduce pregnancy losses in lactating dairy cows after synchronized ovulation.

Content The objective of the study was to investigate whether a treatment with hCG 4 days after AI could reduce pregnancy losses in lactating dairy cows. Cows of a dairy herd presented to the veterinarian in a fixed reproductive management protocol were treated with an Ovsynch protocol if no corpus luteum (CL) could be palpated per rectum (Group OV). Cows with a CL received cloprostenol (0.15 mg). After 2 days, these cows were treated with buserelin (0.01 mg) and received timed AI 16-20 h later (Group PG). In both treatment protocols, cows were assigned to two groups to receive 2500 IU of hCG i.v. 4 days after AI or to serve as untreated controls (Groups OV-hCG, OV-Control, PG-hCG and PG-Control). Pregnancy diagnosis was carried out 27 days after AI via ultrasonography and 39 days after AI by rectal palpation. Pregnancy losses were defined as cows being pregnant on day 27 but not pregnant on day 39 after AI. Pregnancy rate (PR) by day 27 did not differ among the four groups (35.4, 35.0, 37.0 and 38.0% for Groups OV-hCG, OV-Control, PG-hCG and PG-Control, respectively). Pregnancy losses between day 27 and day 39 after AI were smaller in hCG treated animals in summer but not in autumn and spring. Pregnancy rate by day 39 after AI was higher in PG than in OV groups, but independent of hCG-treatment. In conclusion, treatment with hCG 4 days after AI did not significantly increase PR on 39 days after AI. A positive effect of hCG on pregnancy losses during the summer months warrants further investigation.

Short communication: Evaluation of vaginal discharge following treatment with a progesterone insert

Yellowish discharge after application of intravaginal progesterone releasing inserts is frequently observed in cows. The objective of this study was to compare the bacteriological contamination of the vagina and uterus before and after a treatment with a progesterone insert in heifers. Forty-two Holstein heifers received a progesterone releasing insert [Eazi-Breed controlled internal drug release (CIDR) insert; Pfizer Animal Health, Berlin, Germany] for 7d. The protruding tail had been removed from half of the inserts (no tail group: n=21; tail group: n=21). Nine heifers from the tail group lost the insert within the 7-d treatment interval and were excluded. Heifers identified in estrus were artificially inseminated on d 9 or 10. Vaginal discharge was scored on a 4-point scale [vaginal discharge score (VDS) 0 to 3] and vaginal swabs were taken for bacteriological examination on d 0 and 7 and the day of artificial insemination (AI). Furthermore, cytological and bacteriological samples were obtained from the uterus on d 7 and the day of AI. On d 0, coliforms and Streptococcus spp. were found in vaginal swabs of 21 heifers (64%). On d 7, all heifers showed purulent vaginal discharge (VDS 2 to 3). The VDS was higher in the tail group compared with the no tail group. Arcanobacterium pyogenes, coliforms, and Streptococcus spp. were isolated from the vaginal swabs in 32 of 33 (96%) heifers on d 7. On the day of AI, VDS had improved to 0 or 1 in 96% of the heifers. However, A. pyogenes, coliforms, and Streptococcus spp. were still isolated in 17 of 33 (53%) heifers from the vagina and in 32 of 33 (96%) heifers from the endometrium. Endometrial cytology revealed polymorphonuclear neutrophils (PMN) in 11 heifers (6 to 32% PMN). Five samples exceeded the threshold of 5% PMN, and 2 samples exceeded the 10% PMN threshold, indicative of subclinical endometritis. In conclusion, pyogenic bacteria were found in the vagina and uterus on d 7 and the day of AI after intravaginal progesterone treatment. The severity of the discharge was affected by the protruding tail of the insert.

A survey of drying-off practices on commercial dairy farms in northern Germany and a comparison to science-based recommendations

While dry cow management is important for health, milk production and fertility information on drying-off procedures implemented on commercial dairy farms is lacking. Current drying-off management procedures on commercial dairy farms were evaluated using a questionnaire and results compared with recommendations given in the current literature. Ninety-one participants from a farmer education event completed the survey. On average, cows were dried off seven weeks before calving. Only 9.9 per cent of the farms had a dry period length of five weeks or less. A continuous milking regime without dry period was not established on any farm participating in the survey. Most farmers performed an abrupt drying-off (73.0 per cent). Only 11.8 and 15.0 per cent attempted to lower milk yield prior to drying-off by reducing milking frequencies and adjusting feed rations, respectively. While a blanket antibiotic dry cow treatment was carried out on 79.6 per cent of the farms, selective dry cow treatment was not mentioned by any farmer. Although 77.4 per cent preponed the drying-off date in low-yielding cows, an altered drying-off procedure in high-yielding dairy cows was rare (9.7 per cent). This survey provides an insight into drying-off procedures currently applied on commercial dairy farms in northern Germany.

Predicting stage 2 of calving in Holstein-Friesian heifers

The objective of this study was to predict stage 2 of calving in Holstein-Friesian heifers. Interobserver reliability and predictive values of relevant signs of imminent parturition (i.e., tail raising, stepping, clear and bloody vaginal discharge, turning the head toward the abdomen, and lying lateral with abdominal contractions) were determined. In the first experiment 32 heifers were included. Three investigators participated as observers in the study. They walked through the precalving pen in pairs and observed pregnant heifers (≥267 d pregnant). Cohens kappa results for the interobserver reliability were between 0.51 and 0.91. Thirty-seven Holstein-Friesian heifers were enrolled in the second experiment. Heifers were observed hourly for 24 h/d. Signs of imminent parturition that occurred were noted on a checklist. Compared with a precalving control period (4 d before calving), tail raising, clear vaginal discharge, and bloody vaginal discharge were more likely to occur during the last 24 h before calving. Two equations were built using the GENLINMIXED procedure to predict the hours until parturition. In version 1, the absence or presence of each sign of imminent parturition except turning the head toward the abdomen was included. In version 2, hours until parturition were estimated with the factors days of gestation, tail raising, and clear vaginal discharge. Relaxation of the broad pelvic ligaments and teat filling were evaluated twice per day. Prediction of calving with these parameters was not satisfying (positive predictive values were between 35.1 and 72.7% depending on the day of gestation). The possibility of excluding calving for the next 12 h was considerably higher, ranging from 88.5 to 97.1%. These results indicate that predicting stage 2 of calving via direct observation of plausible signs is imprecise and therefore not recommendable.

Odor Perception by Dogs: Evaluating Two Training Approaches for Odor Learning of Sniffer Dogs

In this study, a standardized experimental set-up with various combinations of herbs as odor sources was designed. Two training approaches for sniffer dogs were compared; first, training with a pure reference odor, and second, training with a variety of odor mixtures with the target odor as a common denominator. The ability of the dogs to identify the target odor in a new context was tested. Six different herbs (basil, St. Johns wort, dandelion, marjoram, parsley, ribwort) were chosen to produce reference materials in various mixtures with (positive) and without (negative) chamomile as the target odor source. The dogs were trained to show 1 of 2 different behaviors, 1 for the positive, and 1 for the negative sample as a yes/no task. Tests were double blind with one sample presented at a time. In both training approaches, dogs were able to detect chamomile as the target odor in any presented mixture with an average sensitivity of 72% and a specificity of 84%. Dogs trained with odor mixture containing the target odor had more correct indications in the transfer task.

Evaluation of udder firmness by palpation and a dynamometer

Swelling of the mammary gland is an important health status sign for clinical exploration and palpation is a routine diagnostic tool for mastitis detection in dairy cows. Data on repeatability or validity of specific methods of udder palpation are rare. The overall objective was to study the validity of estimates of udder firmness generated by palpation and by using a validated dynamometer. Specifically, we set out to determine within-observer repeatability and between-observer repeatability in 2 specific experiments. Additionally, we compared a 4-point palpation scoring system with estimates obtained with a dynamometer in this study. In a pilot trial, we determined the range of udder firmness of 25 cows and developed an in vitro model for udder firmness. This model enabled training of the observers and allowed investigating a 4-point palpation scoring system. In vivo, udder firmness was determined before and after milking by palpation and by using a dynamometer. Within-observer repeatability based on estimates of udder firmness of 25 cows obtained by 3 observers on a single day by palpation was 0.968. Within-observer repeatability of estimates of udder firmness of 25 cows obtained with the dynamometer by a single observer was 0.997. The coefficient of variation of the same measures was 9.1%. To determine between-observer repeatability (palpation: 0.932; dynamometer: 0.898), udder firmness of 100 cows was measured on 4 different days by 9 observers in experiment 2. Udder firmness in dairy cows could be measured repeatably with the dynamometer and by palpation, especially when performed by a single observer. Estimates of udder firmness generated by palpation and with the dynamometer were moderately related (correlation coefficient = 0.54). Training of observers through the pilot trial or practical experience in the 4 d of the study in experiment 2 did not improve the correlation. Further research is warranted to understand how udder firmness develops in infected udders.

Usage of milking gloves and teat sealer on German dairy farms

Thirty-three fourth year veterinary medicine students visited dairy farms, to fill in a questionnaire, and to provide advice in two subject matters, i.e. wearing milking gloves and using teat sealer in combination with antibiotic dry cow treatment. Two communication strategies (i.e. argument-based vs. emotion-based) were randomly applied to communicate background information related to the two subject matters. Four weeks after the visit the farmers were interviewed by telephone to evaluate the effectiveness of the two strategies using a follow up questionnaire. In total 366 German dairy farms were visited between September and November 2010. 278 follow up questionnaires were filled in after 33±8 days. Wearing gloves improved from 72.0% to 78.8% (n=250). Only 25.9% and 21.3% (n =108) at follow up farmers cleaned gloves after every cow. However, cleaning gloves at least after every milking group increased from 76.9% at the first visit to 88.0% (n= 108) at the second interview. The attitude towards using gloves during milking improved significantly. 69.6% (90.9% at follow up, n=263) of the farmers thought gloves were hygienic; 81.7% (86.7% at follow up) found them protective for the skin, and 63.5%(86.7% at follow up) believed gloves were effective for mastitis prevention. Only 18.7% (n=273) (22.7% at follow up) of the participants always used internal teat sealer for drying cows off; 11.0% (12.8% at follow up n=273) used teat sealer sometimes. 58% (n=231) of the farmers did not have an opinion about the efficacy of teat sealer. At the follow up survey 42.4% farmers were still not convinced. Efficancy of the two communication strategies was similar.