Uterine Microbiota and Immune Parameters Associated with Fever in Dairy Cows with Metritis

ObjectiveThis study aimed to evaluate bacterial and host factors causing a fever in cows with metritis. For that, we investigated uterine microbiota using a metagenomic sequencing of the 16S rRNA gene (Study 1), and immune response parameters (Study 2) in metritic cows with and without a fever.Conclusion/SignificanceOur study is the first to show a similar microbiome between metritic cows with and without a fever, which indicates that the host response may be more important for fever development than the microbiome. Bacteroides pyogenes was identified as an important pathogen for the development of metritis but not fever. The decreased inflammatory response may explain the lack of a febrile response in the MNoFever group.     

Fertility in Dairy Cows Managed for Calving Intervals of 12,15 or 18 Months

Effects on reproduction in a total of 135 dairy cows managed for calving intervals of 12, 15 or 18 months (72, 38 and 25 cows respectively) were studied. The cows were of the Swedish Red and White Breed (SRB) and the Swedish Freisian Breed (SLB) and were housed in 2 different herds with 3 different management systems (tied, loose, and tied but milked in a milking parlour; mixed). The cows in one of the herds (48 cows) were assigned for milking either 2 times or 3 times a day. When comparing conception rate at 1st insemination (AI) and the percentage of cows finally pregnant, we found no significant differences between the 3 calving interval groups, however, a tendency for a higher conception rate with a 15 months' interval compared with a 12 months' interval was found in one of the herds (50% vs 41.5%). The percentage of finally pregnant animals varied between 81% and 100%, but this variation was mainly attributed to the herd rather than calving interval group. A significantly higher percentage of cows was treated for anoestrous in the 12-month group than in the 15-month group in one of the herds (28.6% vs. 5.3%). The frequency of ovulations with external heat signs increased with ovulation number up to the 4th ovulation and thereafter remained stable. No significant difference was found in number of AIs required per conception with respect to calving intervals, breeds, or milking frequency groups. However, cows milked 3 times a day had a significantly longer interval from the 1 st AI to conception compared with cows milked 2 times a day (45.8 days vs 17.6 days, p<.01). Cows kept loose exhibited 1st ovulatory oestrous, approximately 2 weeks earlier (55.9 days vs 69.7 days, p<.05) than their herd mates kept tied. In conclusion, our study shows that lengthening the calving interval to 15 or 18 months may have a positive influence on reproduction in terms of less need for treatments of ovarian disorders and higher conception rates. Our results also indicate that milking 3 times a day may have negative effects, and keeping cows in a loose-housing management system may have positive effects on ovarian function. kw|Keywords|k]reproduction; k]extended calving intervals; k]cattle; k]milking frequency     

奶牛瘤胃微生物研究进展和趋势

近年来在奶牛试验中,对瘤胃微生物的研究引起了人们越来越多的兴趣。这些研究的目的多是将微生物组成变化与日粮组成、宿主生产性能(如饲料效率,产奶量,乳脂等)、健康(如瘤胃酸中毒和亚急性酸中毒)以及环境(如甲烷排放)联系起来,另外还有一些研究则强调了微生物在多种反刍动物瘤胃发育中的作用。关于奶牛瘤胃微生物的大部分发现都是基于扩增子测序,可以揭示瘤胃微生物的分类组成,以及在不同处理条件下瘤胃菌群的变化。尽管新兴的宏基因组学和宏转录组学能够深入探索瘤胃微生物的功能,但在数据分析和解释方面也带来了更多的挑战,如目前大多数论文都严重依赖于相关性和推测分析。综述了奶牛瘤胃微生物研究的进展和局限,包括瘤胃微生物与产奶效率、甲烷排放以及瘤胃发育的关系,以及奶牛瘤胃微生物未来的研究趋势。     

Effects of Isoflavone-Enriched Feed on the Rumen Microbiota in Dairy Cows

In this study, we compared the effects of two diets containing different isoflavone concentrations on the isoflavone transfer from feed into milk and on the rumen microbiota in lactating dairy cows. The on-farm experiment was conducted on twelve lactating Czech Fleckvieh x Holstein cows divided into two groups, each with similar mean milk yield. Twice daily, cows were individually fed a diet based on maize silage, meadow hay and supplemental mixture. Control group (CTRL) received the basal diet while the experimental group (EXP) received the basal diet supplemented with 40% soybean isoflavone extract. The average daily isoflavone intake in the EXP group (16 g/day) was twice as high as that in the CTRL group (8.4 g/day, P<0.001). Total isoflavone concentrations in milk from the CTRL and EXP groups were 96.89 and 276.07 μg/L, respectively (P<0.001). Equol concentrations in milk increased from 77.78 μg/L in the CTRL group to 186.30 μg/L in the EXP group (P<0.001). The V3-4 region of bacterial 16S rRNA genes was used for metagenomic analysis of the rumen microbiome. The experimental cows exhibited fewer OTUs at a distance level of 0.03 compared to control cows (P<0.05) and reduced microbial richness compared to control cows based on the calculated Inverse Simpson and Shannon indices. Non-metric multidimensional scaling analysis showed that the major contributor to separation between the experimental and control groups were changes in the representation of bacteria belonging to the phyla Bacteroidetes, Proteobacteria, Firmicutes, and Planctomycetes. Surprisingly, a statistically significant positive correlation was found only between isoflavones and the phyla Burkholderiales (r = 0.65, P<0.05) and unclassified Betaproteobacteria (r = 0.58, P<0.05). Previous mouse and human studies of isoflavone effects on the composition of gastrointestinal microbial populations generally report similar findings.     

Management of Calving in Norwegian Cubicle-Housed Dairy Herds

Sixty of the 65 dairy farms with cubicle houses in the Norwegian county of Oppland were included in a field study of the management of calving in 1990. The farmers recorded the location of the cow when giving birth, farmer presence and whether assistance was given during calving, occurrence of suckling, and time after birth when cow and calf were separated. Such data were recorded for a total of 1125 calvings. About 10% occurred on pasture, while 78% of the remaining calvings took place in the cubicle-equipped section. Thirteen percent calved in a calving pen, the remaining cows being tethered at the time of calving. Thirty-two percent of the calvings took place in houses lacking a calving pen altogether. Farmers were present during 41% of the calvings. Suckling most frequently occurred after pasture calvings, and was least frequent after calvings within the cubicle-equipped section of the cowhouse. Injuries to the calf caused by trampling or contact with fittings etc. were rare, and no more common in association with calving in the cubicle-equipped section than with calving taking place with the cow isolated from the rest of the herd. All calves were removed from their dams within 24 h after birth.     

Socio-Spatial Relationships in Dairy Cows

Farm animals may serve as models for evaluating social networks in a controlled environment. We used an automated system to track, at fine temporal and spatial resolution (once per minute, ±50 cm) every individual in six herds of dairy cows ( Bos taurus ). We then analysed the data using social network analyses. Relationships were based on non-random attachment and avoidance relationships in respect to synchronous use and distances observed in three different functional areas (activity, feeding and lying). We found that neither synchrony nor distance between cows was strongly predictable among the three functional areas. The emerging social networks were tightly knit for attachment relationships and less dense for avoidance relationships. These networks loosened up from the feeding and lying area to the activity area, and were less dense for relationships based on synchronicity than on median distance with respect to node degree, relative size of the largest cluster, density and diameter of the network. In addition, synchronicity was higher in dyads of dairy cows that had grown up together and shared their last dry period. This last effect disappeared with increasing herd size. Dairy herds can be characterized by one strongly clustered network including most of the herd members with many non-random attachment and avoidance relationships. Closely synchronous dyads were composed of cows with more intense previous contact. The automatic tracking of a large number of individuals proved promising in acquiring the data necessary for tackling social network analyses.     

Differential Cell Counting in Fraction-Collected Milk from Dairy Cows

Cell con-centrations and cell populations were studied in fraction-collected milk by use of cytofluorometric methods. The results indicate differences in the condition of udders producing milk with more and less than 100 000 cells per ml, respectively     

Incidence of Infertility in Dairy Cows

The incidence of anoestrus, suboestrus, delayed ovulation, cystic ovaries, repeat breeder cows, endometritis and other forms of infertility was studied in 283 herds over a period of eight years (2,304 cases). The total incidence of infertility (0.111 cases per cow per year) varied significantly from year to year. The peak of the seasonal variation occurred in December-April and did not correspond with the seasonal variation in calving. Both the size of herd and the type of housing affected the incidence of infertility, but the differences were great in respect of the various diagnoses. The incidence of ketosis by herd correlated significantly with the incidence of infertility by herd.     

Listeria monocytogenes in Faeces from Clinically Healthy Dairy Cows in Sweden

Faecal samples from 102 clinically healthy dairy cows, representing 34 farms in the Swedish province of Uppsala, were analysed for the presence of Listeria spp. using an enrichment procedure. Listeria monocytogenes was isolated from six (6%) and L. innocua from 2 (2%) cows. From each of the 6 samples positive for L. monocytogenes, 5 isolates were further characterised by restriction enzyme analysis using the 3 enzymes Apa I, Sma I, and Asc I, followed by pulsed-field gel electrophoresis. Three of the L. monocytogenes positive cows lived at the same farm, and they all harboured the same clonal type. One of these 3 cows also harboured a further clonal type of L. monocytogenes. The fact that one of the cows harboured 2 different clonal types of L. monocytogenes is important from an epidemiological point of view when routes of infection are to be investigated.     

Hormonal Interrelationships in Postpartum Suckled Dairy Cows

Three cross-bred cows calved in March and April and were followed until day 62 after parturition. Each animal was suckled by 2 calves ad libitum. All calves were removed from the cows on day 55 after parturition. Blood was collected 3 times per day from the jugular vein by venipuncture. On 4 occasions after parturition - i.e. days 7–8, 21–22, 35–36 and 49–50, the cows were bled through a jugular venous catheter every 30 min during the 24 h. The plasma samples were analyzed for the content of 15-keto-13,14-dihydro-PGF2α (main PGF2α metabolite), LH, prolactin, Cortisol and progesterone by radioimmunoassay methods. The concentration of PGF2α increased from 280 to 730 pmol/1 within the last 4 days before parturition. The highest geometric mean was 3106 pmol/1 on the day of parturition. Thereafter a steady decrease of PGF2α metabolite concentration was seen until day 21 when it reached plateau at 148 pmo/1. In all cows plasma LH concentrations increased significantly (P<0.05) from about 1.6 µg/l on days 7–8 to 2.4 µg/1 on days 21–22 post partum. The frequency of LH pulses showed no tendency to increase as the postpartum period progressed and averaged 6.5 pulses/24 h. Mean plasma LH concentrations increased from 2.1 µg/l 2 days before weaning to 3.2 µg/l 2 days after weaning (P<0.05). LH peaks occurred less frequently in association with prolactin and Cortisol peaks than in their absence. A partial positive correlation between PGF2α metabolite and Cortisol (r = 0.30) was found on days 7–8 post partum. Correlation between prolactin and Cortisol on days 7–8 and 21–22 post partum was also positive (r = 0.20 and r = 0.27, respectively). There was a negative correlation between LH and Cortisol on days 7–8 (r = −0.27) and days 49–50 (r = −0.21) post partum. The first and short progesterone increase observed after weaning was terminated in conjuction with PGF2α metabolite peaks.     

Bisection of Bovine Morulae and Blastocysts from Superovulated Danish Dairy Cows

Sixtyfour compacted morulae and blastocysts were bisected with a microscalpel. The majority of the demi-embryos (n= 122) were reinserted into separate zona pellucidae (ZP) before non-surgical transfer to 113 syncronized recipients, as singles (n = 98) (DE-S) or in pairs (n = 30) (DE-P). Thirty non-manipulated embryos (E) were transferred during the same period and served as controls. Pregnancies were diagnosed by rectal palpation 4–7 weeks after transfer. The pregnancy rates for DE-S, DE-P and E were 32%, 53% and 40%, respectively (P > 0.05). A substantial number of abortions were recorded between 50 and 250 days of pregnancy among the recipients with DE-S. The fetal survival rate for DE-S was reduced to 21% and significantly lower (p < 0.05) than the survival rates of DE-P (43%) and E (40%). The quality of DE and the presence of ZP did not significantly influence the results. No conclusive reasons for the fetal loss could be found but different possibilities are discussed.     

Behavior and Performance of Dairy Cows After Transfer from Tied to Cubicle Housing

Behavior and performance changes when tied dairy cows were moved to a loose housing system in a cubicle system were investigated. Behavioral observations were made for 3 consecutive days in 3 periods after transition. The cows (n = 105) were observed on 18 sampling occasions for 1 month. Recordings were made of body positions and general and social behaviors. Monthly milk records were collected 1 year before and 1 year after transition. Cows walked more during the 1st observation period than during the other periods (p < .05). Walking activity also differed between days when nested to period (p < .05). During the 1st period, cows ruminated while standing more than during the 3rd period (p < .05). Cows ate and groomed less and vocalized more during the 1st period (p < .05). It was concluded that after transition from a tied to a cubicle system, several behaviors were affected during the 1st days, and milk production of multiparous cows was negatively affected, although this effect was not long-term.     

Studies of the Blood Lipid Pattern in Healthy Dairy Cows

The object was to add to the knowledge of certain blood parameters of significance for charting the lipid metabolism in dairy cows. The result may be summarized as follows:     

Effect of Feeding on Reproductive Performance in Finnish Dairy Cows

The effect of 2 types of feeding on the involution of the genital tract and on the fertility was studied in 79 Finnish dairy cows on a research farm. The cows were fed twice a day with home-produced feed in accordance with the Finnish feeding standard. The cows were divided according to the type of feed into a hay-urea group and a silage group. The cows were examined clinically by rectal palpation 3 times a week during 8 weeks postpartum. The time required for the complete involution of uterus and cervix was recorded. The cows in the silage group had a significantly longer time in uterine involution, a lower fertility rate at first insemination and a longer interval from calving to conception than those in the hay-urea group. The pregnancy rate in the first insemination was in the hay-urea group 91 % and in the silage group 57 %. The interval between calving and the first insemination was shorter in the hay-urea group than in the silage group; 71.4 ± 10.6 and 74.0 ± 10.3 days, respectively. The interval between calving and conception was in the hay-urea group significantly (p < 0.01) shorter than in the silage group; 74.8 ± 15.1 and 89.5 ± 24.4 days, respectively.