The Postpartum Reproductive Status of Dairy Cows in Two Areas in Iceland*

The paper describes the postpartum (pp) reproductive performance of 252 dairy cows in 2 areas in Iceland, in the north (Eyjafjörður) and in the south (Skeið), during a 12 months period. First pp ovulation occurred significantly earlier in primiparous cows, in cows in Skeið and in cows that calved in September—November. The average time of first pp artificial insemination (ai) was 72 days in both areas. Conception rate to first ai in these cows was 58 % in Eyjafjörður and 53 % in Skeið and the number of ai per conception was 1.6 and 1.8, respectively. In Eyjafjörður, 23 % of the cows were inseminated at the time of first pp ovulation. Sixtytwo percent of these cows conceived. In Skeið, 20 cows were inseminated at the time of first pp ovulation, and 9 or 45 % of these cows conceived. The interval from calving to conception was, on the average, 92 days in Eyjafjörður and 100 days in Skeið. Comparison of results from individual farms showed increase in number of conceptions to first pp ai (35–72 %) and decrease in number of services per conception (2.0–1.3) with increased mean number of days from calving to first ai (62–82 days).     

A Survey of the Postpartum Reproductive Performance of Dairy Cows with Fertility Problems in Southern Iceland

The purpose of this survey was to evaluate the reproductive performance of dairy cows on problem farms in southern Iceland. In all 229 cows on 6 farms were studied. The animals were examined clinically by rectal palpation, once a month. Blood samples were taken 2–5 and 7–10 weeks after calving. The blood samples were analysed for the contents of glucose, urea, inorganic phosphate, calcium and magnesium. Milk samples for progesterone profiles were taken, by the farmer, every 4th day from day 10 postpartum until first oestrus. Because of this sampling method, 128 cows had no rise in progesterone levels, when milk sampling was stopped. These 128 animals were excluded from the study. The results are based on 101 animals. There was a large variation between cows in postpartum reproductive performance. In the total material 1st ovulation occurred later than reported in many other countries. Fifty percent of the cows had ovulated 35 days after calving and 90 percent 70 days after calving. The first luteal phase was short in about 60 % of the cows. The progesterone values assayed from those short cycles were lower than the values assayed from the following cycle. First artificial insemination (ai) was on the average 77 days postpartum (pp). The conception rate to first service was 49 %. Of 100 milk samples taken at the time of ai, 20 had high progesterone value. This indicates a high frequency of luteal phase inseminations. Clinical ketosis was diagnosed in 35 cows. Of these, 31 had a low glucose value. Cows with clinical ketosis ovulated, on the average, later than other animals and 24 ovulated later than 40 days pp. The results indicated that the fertility problems of these cows studied were late ovulations, low conception rate, probably in part, due to luteal phase inseminations, and a high frequency of ketosis which could be caused by low quality feedstuff.     

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.     

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.     

Assessment of Early Postpartum Reproductive Performance in Two High Producing Estonian Dairy Herds

Early postpartum (6 weeks) ovarian activity, hormonal profiles, uterine involution, uterine infections, serum electrolytes, glucose, milk acetoacetate and blood urea nitrogen (BUN) levels were studied in 2 Estonian high producing dairy herd with annual milk production of 7688 (Farm A) and 9425 (Farm B). From each farm 10 cows, with normal calving performance were used. Blood samples for the hormonal (PGF_2α-metabolite, progesterone) analyses were withdrawn. On day 25 PP blood serum samples were taken for the evaluation of metabolic/electrolyte status. On the same day estimation of milk acetoacetate values was done. The ultrasound (US) was started on day 7 PP and was performed every 3^rd day until the end of experiment. Uterine content, follicular activity and sizes of the largest follicle and corpus luteum were monitored and measured. Vaginal discharge and uterine tone were recorded during the rectal palpation. Each animal in the study was sampled for bacteriological examination using endometrial biopsies once a week. Two types of PGF_2α-metabolite patterns were detected: elevated levels during 14 days PP, then decline to the basal level and then a second small elevation at the time of final elimination of the bacteria from the uterus; or elevated levels during first 7 days PP, then decline to the basal level and a second small elevation before the final elimination of bacteria. Endometritis was diagnosed in 5 cows in farm A and in 3 cows in farm B respectively. In farm A, 5 cows out of 10 ovulated during experimental period and in 1 cow cystic ovaries were found. In farm B, 3 cows out of 10 ovulated. In 3 cows cystic ovaries were found. Altogether 40% of cows had their first ovulation during the experimental period. Three cows in farm A and 5 cows in farm B were totally bacteria negative during the experimental period. The most frequent bacteria found were A. pyogenes, Streptococcus spp., E. coli., F. necrophorum and Bacteroides spp. The highest incidence of bacteriological species was found during the first 3 weeks in both farms. All animals were free from bacteria after 5^th week PP in farm A and after 4^th week in farm B respectively. Serum electrolytes and glucose levels were found to be within the reference limits for the cows in both farms. No significant difference was found between farms (p > 0.05). Low phosphorus levels were found in both farms. Significant difference (p < 0.05) was found in BUN levels between farms. In both farms milk acetoacetate values were staying within the reference range given for the used test (<100 μmol/l). The uterine involution and bacterial elimination in the investigated cows could consider as normal but more profound metabolic studies could be needed to find reasons for later resumption of ovarian activity. Some recommendations to changing feeding regimes and strategies should also be given.     

Serum Fructosamine Levels in Dairy Cows Related to Metabolic Status in Early Lactation

Serum levels of fructosamine were assayed in 57 samples from 23 Norwegian Red Cattle dairy cows in early lactation. The animals were assigned to a 22 factorial feeding experiment. The groups differed in energy and protein supply. All samples were collected before morning feeding. The relationship between fructosamine levels and the plasma concentrations of glucose, acetoacetate, free fatty acids, total cholesterol, lipoproteins, triglycerides, total proteins, progesterone and to weight and energy balance was studied. The overall mean fructosamine level was 1.41 ± 0.20 mmol/1 ranging from 0.92–1.92 mmol/1. Significant relationships were recorded between fructosamine and the concentrations of glucose, acetoacetate, free fatty acids, triglyceride, total cholesterol and energy and weight balance. Free fatty acids and cholesterol showed the best correlation with fructosamine (rs =–0.67 and 0.70, respectively, p < 0.001). The levels of fructosamine increased significantly between 2 and 4 weeks and between 4 and 8 weeks after calving. Animals with a weight gain during 3 weeks prior to fructosamine measurement had higher fructosamine levels than those showing a weight loss (<–7 kg/week) (p < 0.05). The results indicate that serum fructosamine levels in cows may be of interest as an indicator of metabolic status in the early stages of lactation.     

Vitamin D Status and Hypocalcemic Response to Protamine in Exercised and Non-exercised Dairy Cows

Bone resorption was studied in post parturient cows using intravenous injection of protamine. Protamine inhibits bone resorption and the protamine-induced hypocalcemia can be taken as a measure of this process. The studies were performed in a herd where half of the cows had been tied indoors for 21/2 years, the other half had been given daily exercise during the same period. All animals were fed in the same way. The hypocalcémie response to protamine was the same in both groups, which indicates that exercise did not change bone resorption. The serum levels of calcium, inorganic phosphorus and magnesium around parturition did not differ. The daily exposure to daylight increased the serum level of 25-(OH)-chole-calciferol in late summer in the exercised group.     

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.     

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.     

Prepartum and Postpartum Rumen Fluid Microbiomes: Characterization and Correlation with Production Traits in Dairy Cows

Microbes present in the rumen of dairy cows are essential for degradation of cellulosic and nonstructural carbohydrates of plant origin. The prepartum and postpartum diets of high-producing dairy cows are substantially different, but in what ways the rumen microbiome changes in response and how those changes may influence production traits are not well elucidated. Here, we sequenced the 16S and 18S rRNA genes using the MiSeq platform to characterize the prepartum and postpartum rumen fluid microbiomes in 115 high-producing dairy cows, including both primiparous and multiparous animals. Discriminant analysis identified differences between the microbiomes of prepartum and postpartum samples and between primiparous and multiparous cows. 18S rRNA sequencing revealed an overwhelming dominance of the protozoan class Litostomatea, with over 90% of the eukaryotic microbial population belonging to that group. Additionally, fungi were relatively more prevalent and Litostomatea relatively less prevalent in prepartum samples than in postpartum ones. The core rumen microbiome (common to all samples) consisted of 64 bacterial taxa, of which members of the genus Prevotella were the most prevalent. The Chao1 richness index was greater for prepartum multiparous cows than for postpartum multiparous cows. Multivariable models identified bacterial taxa associated with increased or reduced milk production, and general linear models revealed that a metagenomically based prediction of productivity is highly associated with production of actual milk and milk components. In conclusion, the structure of the rumen fluid microbiome shifts between the prepartum and first-week postpartum periods, and its profile within the context of this study could be used to accurately predict production traits.     

Effect of Single Nucleotide Polymorphisms of Toll-Like Receptor 4 (TLR 4) on Reproductive Performance and Immune Function in Dairy Cows

In dairy cows, inflammatory diseases caused by infection with pathogenic bacteria post calving affect ovarian functions. This study examined the relationship between single-nucleotide polymorphisms (SNPs) of Toll-like receptor 4 (TLR4), reproductive performances [the number of artificial insemination (AI) application and days open], and immune cell functions (apoptosis and migration). Two hundred Holstein cows from the Obihiro University farm were included. The SNPs of TLR4 were genotyped by PCR-restriction fragment length polymorphism (PCR–RFLP) method. Polymorphonuclear leukocytes (PMNs) and peripheral blood mononuclear cells (PBMCs) were isolated from whole blood. The number of AI application in the animals with T/C genotype in the TLR4 exon3 was lower than that in animals with C/C genotype (1.6 ± 0.2 and 2.2 ± 0.2, respectively). Among the animals with TLR4 exon3 polymorphisms, the days open was shorter for the T/C cows than that for C/C cows (100.7 ± 6.9 days and 136.6 ± 9.0 days, respectively). The SNPs in the TLR4 intron did not affect the number of AI and days open. The apoptosis percentage of PMNs treated with lipopolysaccharide (LPS; 0.001 and 1 μg/ml) tended to be lower in the T/C genotype compared to that in the C/C genotype. The transmigration rates of PMNs, and IL-1β production in PBMCs were tended to be higher for the animals with the T/C genotype compared to those for animals with the C/C genotype. Taken together, these results suggest that TLR4 polymorphisms offer a meaningful tool to judge the reproductive potential and immune activity in individual cows.     

Selenium Levels and Glutathione Peroxidase Activity in Blood,Plasma and Reproductive Organs in Dairy Cows

Selenium levels and glutathione peroxidase activity were determined in blood and reproductive organs in 12 Norwegian dairy cows at different stages of the oestrus cycle. Blood samples were collected before slaughter, and samples from genital organs were obtained as soon as possible after slaughter. Blood and plasma selenium levels were significantly correlated with selenium levels in follicular fluid, and in ovarian and uterine tissues, but not with the levels in corpora lutea. The activity of blood glutathione peroxidase was significantly correlated with that in ovarian and uterine tissue, but not with activity in corpora lutea and follicular fluid. No effect of stage of oestrus cycle on selenium content or glutathione peroxidase in reproductive tissue was observed.     

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.     

Carbon Economy of Sour Orange in Relation to Mycorrhizal Colonization and Phosphorus Status

The effects of plant phosphorus (P) status and the mycorrhizal(M) fungus, Glomus intraradices Schenck & Smith, on thecarbon (C) economy of sour orange (Citrus aurantium L.) weredetermined during and following active M colonization. Therewere four treatments: M seedlings grown at standard-strength(1 mM) P (M1) and nonmycorrhizal (NM) plants grown at one, twoand five times standard-strength P (NM1, NM2 and NM5). Mycorrhizalcolonization, tissue dry mass, P content, root length and leafarea were determined in five harvests from 6 to 15 weeks ofage. Rate of C assimilation (A) was determined at 7, 8 and 12weeks by gas exchange. Partitioning of ¹⁴ C was determined from7 to 15 weeks using a 10-min pulse followed by a 24-h chaseperiod. For a given attribute, M1 plants were compared to thecurve defining the NM response as a function of tissue P concentration.In contrast to the large effects of P nutrition on C economyof sour orange, M effects were generally subtle. Mycorrhizaeincreased the root biomass fraction, the root length/leaf arearatio and the percentage of ¹⁴C recovered from below-groundcomponents. A higher percentage of below-ground ¹⁴ C was inthe respiration and soil fractions in M than NM plants of equivalentP status. Mycorrhizal plants tended to enhance A only for abrief period. Mycorrhizal plants had lower relative growth ratesthan NM plants of equivalent P status, suggesting that the temporarilyenhance A of M plants did not fully compensate for their greaterbelow-ground carbon expenditure. Problems of interpreting thedynamic effects of mycorrhizae on C economy that are independentof P nutrition are discussed.Copyright 1993, 1999 Academic Press Citrus aurantium L., sour orange, carbon economy, ¹⁴carbon, CO₂ assimilation, vesicular-arbuscular mycorrhizae, phosphorus fertilization, phosphorus nutrition     

Variations in Copper Concentration and Ceruloplasmin Activity of Dairy Cows in Relation to Lactation Stages with Regard to Ceruloplasmin to Copper Ratios

Variations of copper (Cu) concentration and ceruloplasmin (Cp) activity in serum and plasma of dairy cows at different stages of lactation were assessed in 240 Holstein dairy cows. Furthermore, ceruloplasmin to copper ratios were also investigated. The cows were classified according to their lactation stages into four different groups as close-up stage (3–1 week(s) antepartum), fresh lactation stage (0–1 week postpartum), early lactation stage (3–5 weeks postpartum), and mid-lactation stage (15–18 weeks postpartum). Each group consisted of 60 multiparous cows. Serum and heparinised plasma samples were obtained from each cow. Concentrations of serum copper (sCu) and plasma copper (pCu) as well as activities of plasma Cp (pCp) were higher in the group of fresh lactation stage than other groups (P < 0.05). Serum Cp (sCp) exhibited no significant difference between fresh lactation and early lactation groups (P > 0.05). Low correlations were obtained between sCp and pCu, sCp and sCu, and sCu and pCu. Plasma copper concentration and plasma ceruloplasmin activity were higher than serum copper concentration and serum ceruloplasmin activity, respectively (P < 0.001). The ratios of Cp activity to Cu concentration (Cp/Cu) were not significantly changed in the different lactation stages of dairy cows (P > 0.05). Use of sCp/pCu and sCp/sCu rather than pCp/pCu will reduce the calculated value of Cp/Cu. Furthermore, for evaluation of copper status, use of sCp/sCu or sCp/pCu identified more animals as ‘low’ and ‘marginal’ than using pCp/pCu (P < 0.001). It can be concluded that ceruloplasmin and copper undergo a physiological increase just after calving; thus, their values should be interpreted with caution during assessment of copper status. Plasma measurements should be used for calculation of Cp/Cu, and further research is required to refine diagnosis criteria for use of such ratio in determining copper status in dairy cows.