Effect of eprinomectin pour-on treatment around calving on reproduction parameters in adult dairy cows with limited outdoor exposure

The objective of this study was to investigate if treatment of cows with eprinomectin around calving had any beneficial effects on the calving to first artificial insemination interval, calving to conception interval, and number of services per conception in totally- and semi-confined dairy herds. In totally-confined herds lactating- and dry-cows were housed throughout the summer and had no access to pasture. In semi-confined herds lactating- and dry-cows had limited outdoor exposure to a small pasture or paddock but were still fed a ration that met all their nutritional requirements. The study was carried out between February 2002 and February 2003 in 35 herds (2381 cows) located in Quebec, Ontario and Minnesota (USA) participating in a larger clinical trial. The herds kept electronic reproduction records. Cows were randomly allocated to receive eprinomectin or a placebo, with treatment being administered on or close to the day of calving. Monthly bulk tank milk samples from each farm were tested with an indirect ELISA using a crude Ostertagia ostertagi antigen and these data were averaged over the study year. The optical density ratio (ODR) values were then dichotomized into high and low using a cut-point of 0.50. Treatment effects were analyzed using Cox proportional hazards survival models with herd frailty effects for calving to conception and calving to first service intervals. Aalen's linear hazards model was used to investigate time-varying effects in the Cox models. A random effects poisson regression model was used to model the number of services per conception. Other predictor variables tested in the models were lactation number, calving season, study site, peak milk production, ODR and the lactating- and dry-cow housing variables. Overall, there was no significant effect of treatment on the three indices of reproductive performance. The effect of season of calving depended on how much time had passed since calving. Presumably this effect reflected a seasonal effect at the time of breeding. Hazard of conception in younger cows was higher than in older cows. Early bred cows tended to have a higher number of inseminations per conception than those bred late. The results of the study suggested that eprinomectin treatment at calving was not beneficial to reproduction.     

Effect of a peri-parturient eprinomectin treatment of dairy cows on milk production

AIM: To quantify and economically evaluate the effect on milk production of peri-parturient treatment of dairy cows with eprinomectin. METHODS: On 3 farms in separate geographic areas of New Zealand, 849 first-calf heifers and multiparous cows were ranked and paired within parity, date of calving and expected milk production. Within pairs, cows were randomly allocated to treatment with either a commercial formulation of eprinomectin, applied at a dose rate of 500 mug/kg liveweight, or an equivalent volume of vehicle containing no antiparasitic agent and administered at the same dose volume, generally within the first week post-calving. On each farm, trial cows shared the same pasture. Over a single lactation, records were maintained of milk quantity and content. RESULTS: Trichostrongylid eggs were identified in pre-treatment faecal samples from all farms, verifying the presence of gastrointestinal parasites. Overall 25.5% of the cows sampled were positive for nematode eggs, but only 8% had counts 50 eggs per gram of faeces (epg). Daily milk volume, milk protein and milksolids (yield of milk fat + milk protein) were higher for eprinomectin-treated multiparous cows than for controls (milk volume: 20.36 l/day vs 19.76 l/day, p=0.005; milk protein: 0.700 kg/day vs 0.685 kg/day, p=0.012; milksolids: 1.613 kg/day vs 1.583 kg/day, p=0.031, respectively). The daily value of the increased production from eprinomectin-treated multiparous cows was estimated to be NZ0.034 dollar for milk fat (p=0.095) and NZ0.078 dollar for milk protein (p=0.012), equating to NZ0.104 dollars for milksolids (p=0.031), averaged over the whole lactation. No significant difference in milk production was detected between treated and control first-calf heifers. Averaged over the whole herd, the peri-parturient treatment of multiparous cows and first-calf heifers with eprinomectin increased daily milk volume and milk protein production of treated vs control cows (19.28 l/day vs 18.86 l/day, p=0.020, and 0.661 kg/day vs 0.650 kg/day, p=0.047, respectively). CONCLUSION: These data provide evidence that the use of a peri-parturient treatment of eprinomectin on multiparous cows can increase their production of fluid milk and milksolids.     

Heat stress in dairy cows. Its effect on reproduction

The effects of heat stress are most pronounced in the lactating dairy cow. The effects manifest themselves in several physiologic mechanisms and include negative effects on the duration of estrus, embryonic development, uterine blood flow, hormonal relationships, fetal growth, and subsequent milk yield.     

Effect of eprinomectin treatment on milk yield and quality in dairy cows in South Tyrol, Italy

The effect of treatment with eprinomectin on milk yield, milk composition and somatic cell counts (SCCs) was studied in 105 dairy cows located on seven farms in South Tyrol, Italy. On each farm, half of the animals were treated with eprinomectin and the other half were used as an untreated control group. Three test day records per animal were obtained before treatment (days -117, -75 and -33) and another three test day records were obtained after treatment (days 22, 62 and 131). Test day records comprised milk yield, milk composition, SCC and days in milk. On the day of treatment, blood samples and faecal samples were taken for parasitological analysis. Cows with positive faecal egg counts yielded less milk. A significant effect of eprinomectin on milk yield was observed after treatment and was most pronounced on the second and the third test days after treatment (+1.90 kg [P=0.002] and +2.63 kg [P<0.001], respectively). Furthermore, a significant decrease in SCC was observed on the second test day after treatment.     

Effects of nutrition on reproduction in dairy cows

It is clear that nutrition is closely related to reproduction in the dairy cow. In addition to classic nutrient deficiency and excess, dry cow body condition and postpartum energy balance have a major impact on fertility. Dry cow rations must be designed to prevent milk fever, dystocia, retained placenta, other calving problems, and metritis. Most importantly, milk yield and reproductive performance should be regularly monitored to detect nutritionally associated health and performance changes that precede impairment of reproductive function.     

The effect of prolonged movement restriction of dairy cows on biochemical parameters

In thirty-three dairy cows--first calves, the influence of hypokinesis on biochemical parameters was studied over three lactation periods. The cows of the experimental group (n = 15) were reared in steel cages enabling only minimum movement, whereas the control group (n = 18) was housed loosely. It was found out that the permanent movement restriction led to a statistically significant decrease in hemoglobin and hematocrit concentrations, as well as in aspartate aminotransferase activity. In comparison with the control group, a significant decrease was also observed in substances of the lipid group--cholesterol, triglycerides and total lipids. Similarly, thyroxin and total proteinemia were lower.     

Nutrition and reproduction in dairy cows

Diagnosis of nutritional effects on herd fertility requires a systematic analysis of reproductive records in addition to quantifying the feeding program on the farm. Corroborative laboratory tests for specific deficiencies may be useful.     

The effect of repeated, four-weekly eprinomectin treatment on milk production in pasture-based, seasonally-calving dairy cattle

A randomised clinical trial from the North Island of New Zealand was conducted to assess the effect of repeated anthelmintic treatment on milk production, and to assess factors that affect treatment response. Nine hundred and twenty three multiparous, lactating dairy cattle from three pasture-based, spring-calving dairy herds were enrolled in this trial. Within each herd, cattle were stratified on age and calving date, and were randomly allocated to treatment (n=319) or control (n=604) groups. The treatment group received ≥0.05mg/kg of topical eprinomectin every 28 days for eight treatments during lactation. Pooled-milk from treated cows and bulk-milk samples were obtained at each treatment and analysed with an Ostertagia antibody ELISA, expressed as optical density ratios (ODR). Bi-monthly milk data were collected and expressed as energy-corrected milk (kg/day; ECM). A linear mixed model was used to analyse ECM, with cow as the random effect. The effect of anthelmintic treatment on days from calving, and start-of-mating, to conception were analysed with Cox-proportional hazard models. ODR values ranged from 0.6 to 1.3; there were no differences in ODR between herds (p=0.12), or between pooled-milk from treated cows and bulk-milk (p=0.26). Repeated treatments had no effect on daily ECM yields (p=0.74). However, there was a significant treatment×herd interaction (p=0.03); treatment increased ECM in one herd by 0.781kg/cow/day (p=0.015), but resulted in a non-significant decrease in the other two herds. A curvilinear interaction existed between days-in-milk and treatment response (p=0.039); the greatest treatment effect occurred during mid-lactation. Previous year milk production (p=0.46) and age (p=0.11) did not influence the effect of treatment on ECM. Treatment had no effect on any reproductive parameter. In conclusion, under New Zealand pastoral conditions, anthelmintic treatment increased milk production in one herd, but had no effect in two other herds. Further work is needed to identify why this variation in gastro-intestinal parasitism occurs.     

The reproductive performance of New Zealand dairy cows after induction of calving

Induction of premature calving contributes to subsequent failure of some dairy cows to become pregnant and calve. Of a sample of 276 cows 16.7% failed to calve the following year despite the occurrence of oestrus relatively early after calving, and several matings. The cows which did conceive had a normal first-mating calving rate of 53.9%, requiring 1.7 matings per pregnancy. Two of the 18 survey herds under consideration suffered lengthy calving-to-first-mating oestrus intervals, presumably because the induced cows were in poor condition at the time of calving.     

Evaluation of the effects of treating dairy cows with meloxicam at calving on retained fetal membranes risk

Some non-steroidal anti-inflammatory drugs increase the risk of retained fetal membranes. This is the first study to investigate the effects of meloxicam on the risk of retained fetal membranes. Administration of meloxicam to dairy cattle immediately following calving revealed no differences in the incidence of retained fetal membranes between meloxicam-treated and untreated animals. There was no difference between the 2 groups in the incidence of periparturient diseases following calving. Meloxicam can be used on the day of calving in lactating cows without increasing the risk of retained fetal membranes.     

Nutrient balance in the diet of spring calving, pasture-fed dairy cows

AIMS: To report the nutrient composition of pastures fed to spring-calving dairy cows in the Manawatu region of New Zealand, and describe changes in the nutrient composition of these pastures over a 12-month period. Having done this we sought to: (1) compare the nutrient composition of the pasture offered with the nutrient requirements of spring-calving dairy cows; (2) identify periods when individual nutrient surpluses and deficits are likely; and, (3) identify nutrients that demonstrate a high level of variability between sampling occasions. METHODS: Seven farms took part in the study. Each farm was visited monthly from August 1996 to July 1997. Samples of pasture were taken at each visit and submitted for estimation of dry matter (DM), metabolisable energy (ME), crude protein (CP), non-structural carbohydrate (NSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), chlorine (Cl), sulphur (S), iron (Fe), copper (Cu) and zinc (Zn), and dietary cation-anion differences (DCAD). RESULTS: Sampled pastures were characterised by low to marginal ME, NSC, Ca, Mg, and Zn concentrations when compared with recommended dietary nutrient concentrations for lactating and non-lactating dairy cattle in New Zealand. Analyses revealed relatively high CP, NDF and K concentrations, and DCAD. CONCLUSIONS: These analyses identify broad trends in the nutrient balance of a pasture-only feeding regime and provide a useful reference for planning feed strategies for spring-calving, pasture-fed dairy herds in this region. Recommended changes to on-farm practice should be made after considering the whole farm system, rather than being made solely on the basis of perceived deficiencies or excesses of individual nutrients.     

Variations in blood composition in dairy cows during pregnancy and after calving

The effects of pregnancy and of the onset of lactation on blood composition was studied in 21 Friesian cows. Among the 23 components studied only seven showed significant variations. Serum iron decreased at the end of pregnancy while creatinine increased throughout the last six months. There were decreases in blood glucose, cholesterol and alanine aminotransferase at the end of pregnancy. Triglycerides increased rapidly after drying-off and serum urea increased in the first month after calving.     

Effects of calving age, breed fraction and month of calving on calving interval and survival across parities in Irish spring-calving dairy cows

The objective of this study was to investigate the effect of parity, age at calving, percentage North American Holstein-Friesian and calving date on subsequent calving interval and survival to facilitate the estimation of transition probabilities for month of calving. The economic value of traits that influence calving date, age distribution and survival can be assessed in models using a transition probability matrix. Such a matrix contains the probabilities that a cow of a particular age or breed calving in a particular month will calve in the same, an earlier or later month next year, or be culled. Following editing 1,046,855 calving records in spring-calving herds between the years 1990 and 2004 were analysed. Shorter calving intervals were associated with cows calving later in the calendar year. Age at first calving of < 24 months resulted in longer calving intervals to second calving across all levels of Holstein percentage with cows calving for the first time at 25–26 months of age having the shortest subsequent calving interval. Age at second calving of 37–38 months and third calving of 49–50 months were optimum for shorter subsequent calving intervals. Calving interval increased with Holstein percentage across the first 5 parities. Survival rate decreased with later month of calving and with older parities. When survival rate was measured as the ability of the cow to re-calve within 500 days, the highest survival rate was found in cows calving at 25–26 months of age whereas there was a noticeable reduction in survival across all parities in the 88–100% Holstein percent category.     

影响奶牛产犊间隔因素的分析

经对徐州市某奶牛场约800头荷斯坦奶牛1998到1999年产犊间隔与产犊季节、产奶量、产犊胎次、犊牛初生重、犊牛性别等基础资料进行分析，结果表明：产犊季节对产犊间隔有极显著的影响（P＜0.01）；奶牛的产奶量对产犊间隔也有极显著的影响（P＜0.01）；产犊胎次、犊牛初生重及犊牛性别对产犊间隔无显著影响（P＞0.05）。     

Effects of diets fed to dairy cows before and after calving on their plasma progesterone profiles after calving

Four weeks before their predicted mean second lactation calving date, 60 spring-calving Holstein-Friesian cows were blocked into groups of six on the basis of their predicted calving date and body condition score, and allocated at random to one of six dietary treatments in a factorial design: ad libitum grass silage, ad libitum grass silage plus barley straw or ad libitum grass silage plus 3 kg of concentrates, was offered for four weeks before the expected calving date, and after calving they were offered either 4 kg or 8 kg of concentrates plus ad libitum grass silage for eight weeks. On average, the first luteal activity occurred in all the groups at 29 days after calving. Seventeen of the cows had an atypical first plasma progesterone profile; 12 were anovulatory, three had prolonged luteal phases and two became anovulatory after having been cyclic. The cows offered grass silage only before calving had a significantly shorter mean (se) interval between calving and second luteal activity (44.9 [2.1] days), than the cows offered grass silage and straw (53.5 [1.9] days) or grass silage and concentrates (51.5 [3.2] days) (P<0.05). After calving none of the 28 cows offered grass silage and 4 kg of concentrates started cycling before day 21, whereas five of the 30 cows offered grass silage and 8 kg of concentrates cycled before day 21 (P<0.05).     

Effects of meloxicam on reproduction parameters in dairy cattle

This study was carried out in dairy cattle with the NSAID meloxicam to investigate possible drug effects on different reproductive parameters as well as on the progeny. Forty-one cows received intravenous injection of either meloxicam (Metacam^® 20 mg/mL solution for injection) or placebo at a dose volume of 7.5 mL/100 kg, corresponding to a dose of 1.5 mg meloxicam/kg, i.e. three times the recommended therapeutic dose. Treatment was performed in each phase of reproduction, i.e. once prior to breeding, twice shortly after breeding, once at the beginning of the second and third trimester of gestation and once at the end of the third trimester of gestation. Offspring of the cows were weighed and clinically examined for vitality at birth and after 28 days. No relevant difference between the meloxicam and control group was found in the reproductive performance of the cows or in the body weight development or vitality of the calves.     

Effect of a treatment with eprinomectin or trichlorfon on the yield and quality of milk produced by multiparous dairy cows

The effects of a strategic antiparasitic treatment against Hypoderma species and other parasites on the milk yield, composition, and somatic cell counts of 742 multiparous dairy cattle were investigated on 79 farms in a Hypoderma species-endemic area in western Switzerland; 357 of the cows were treated with eprinomectin, 252 with trichlorfon, and 133 were left untreated. The treatments were given between October and early December 1998, on average 53 days before calving. Milk yield, fat, protein and somatic cell counts were measured once a month until the end of lactation. Eprinomectin and trichlorfon significantly increased milk yield during the first month after treatment compared with the control cows by 2.14 (P < 0.001) and 2.50 kg per day (P < 0.001), respectively. Initially, the difference between the eprinomectin- and trichlorfon-treated animals was not significant, but the effect of eprinomectin on milk yield was persistent, whereas the effect of trichlorfon decreased significantly by 0.12 kg per day per month (P < 0.05). The somatic cell counts increased significantly slower in the treated cows than in the control cows (P < 0.05). Milk composition was not affected by the treatments.     

Changes in peripheral leukocyte subsets in dairy cows with inflammatory diseases after calving

To clarify the cellular immune system in dairy cows with inflammatory diseases after calving, the leukocyte subsets were examined in Holstein dairy cows. Twenty Holstein cows reared in one herd, were used in this study. Nine cows (Group 1) experienced onset of mastitis or puerperal fever within 2 weeks after calving, and the other eleven cows remained healthy (Group 2) after calving. The numbers of CD3(+), CD4(+) and CD8(+) cells tended to be lower in Group 1 than in Group 2 from the day of calving through week 1. These results suggested that the cows with inflammatory diseases might have experienced a decline in T cells by the day of calving, before the onset of disease.     

Perforated abomasal ulcers in adult dairy cows

Case records of adult dairy cattle with abomasal ulcers admitted to the University of Pennsylvania from 1968 through 1980 were evaluated. Of 6,385 adult dairy cattle admitted during that period, 69 had abomasal ulcers of clinical importance. Of 43 ulcers that had perforated, 17 were associated with local peritonitis and 22 were associated with diffuse peritonitis; 4 had perforated so recently that peritonitis had not had time to develop. Perforated ulcers were found in 40 cows that had recently calved (32 cows with ulcers that had perforated within 4 weeks after calving) and often had concurrent disease(s) (39 cows with at least one other disease). Ten cows with local peritonitis survived, whereas only 2 of the cows with diffuse peritonitis survived.     

Effect of prostaglandin F2 alpha on the fertility of dairy cows after calving

Three hundred and thirty-one dairy cows in six herds were used to study the effect of a single injection of 25 mg dinoprost, a prostaglandin F2 alpha derivative, administered eight days after calving on several indices of fertility. A detailed comparison was made between 113 treated cows and 113 control cows of the same parity, which had calved within seven days of each other on the same farm and had experienced the same degree of dystocia. In cows which had calved without assistance, the treatment reduced the mean interval between calving and first heat from 40 days to 37 days but increased the mean interval between calving and conception from 83 days to 85 days. In cows which had required assistance at calving, the treatment reduced the mean interval between calving and first heat from 44 days to 34 days and reduced the mean calving to conception interval from 86 days to 68 days. The cows which benefited most were those which had required assistance during their second, third or fourth calvings; their calving to conception intervals were shortened by 22.5 days. An average of 1.39 services was required to establish conception in the treated cows which calved unaided, with 70 per cent conceiving to the first service, compared with an average of 1.34 services per conception and a 72 per cent conception rate to first service for their untreated herdmates.(ABSTRACT TRUNCATED AT 250 WORDS)