Direct effects of induced parturition on subsequent reproductive performance of dairy cows from commercial herds in south-western Victoria

SUMMARY Reproductive performance was compared between cows whose previous parturition was induced and non-induced cows with similar calving dates, in 49 winter-calving, pasture-fed, commercial dairy herds in south-western Victoria. Parturition was induced in winter when most cows were between 27 and 35 weeks of pregnancy. Reproductive performance was assessed during the next mating period after induction which was mainly in spring of the same year. Percentages of cows in induced and untreated groups that were not pregnant after the mating period (9.0% and 7.2%, respectively) did not differ significantly. Induction tended to increase the percentage of cows of unknown pregnancy status. Mean percentages for induced and untreated groups were 11.5% and 7.9%, respectively. Induced and untreated groups calved at similar intervals after the planned start of calving in the following year, and the percentages of groups that required induction in that year did not differ significantly. The direct effects of induced parturition on reproduction were therefore concluded to be minimal. In seasonal calving herds, improvements in reproductive performance could be expected among cows whose calving dates were altered substantially by induction, due to increased intervals from calving to mating start date .     

The effects of induced parturition in dairy cows on the incidence of mortality in calves from commercial herds in south-western Victoria

SUMMARY The effects of induced parturition on calf mortality rates were studied in 24 winter-calving, pasture-fed, dairy herds in south-western Victoria. Parturition was induced when most cows were between 27 and 35 weeks of pregnancy. Control groups were selected from cows in the same herds in which calving was not induced. The incidence of mortality within 7 days of birth was much higher among calves from cows in induced groups relative to those in control groups (estimated median herd mortality incidence 72% and 7%, respectively). The incidence of calf mortality was high among groups induced at all stages of pregnancy that were investigated. However, differences in calf mortality incidence, relative to controls, were increased among groups induced at earlier stages of pregnancy.     

The effects of induced parturition on the incidence of clinical disease and mortality in dairy cows from commercial herds in south-western Victoria

SUMMARY The effects of induced parturition on clinical disease and mortality of cows were studied in 51 winter-calving, pasture-fed, dairy herds in south-western Victoria. Parturition was induced when most cows were between 27 and 35 weeks of pregnancy. Control groups were selected from herdmates that were not induced to calve. The incidence of retained placenta was much greater among induced cows of all ages. The proportion of cows affected by any clinical disease other than retained placenta, and the incidence of mortality were much greater after induction among cows aged over 6 years but not among cows aged 3 to 6 years.     

Faecal characteristics and milk production of dairy cows in early-lactation fed diets differing in forage types in commercial herds

Effects of grass–clover silage (GCS) alone or combined with whole-crop cereal silage, maize silage (MS) or ensiled pressed sugar beet pulp (EPSB) on faecal characteristics and performance of early-lactation dairy cows were studied in 26 herds. Data were analysed with herd as the experimental unit and correlation coefficients among the variables were estimated. Feeding MS combined with GCS resulted in faeces of a firmer consistency (P?P?r?=?0.83, P?r?=??0.54, P?r?=?0.63, P?相似文献   

Stillbirth parturition reduces milk production in Holstein cows

Stillbirth is defined as calf mortality shortly before, during, or shortly after parturition. Economic losses to the dairy industry in the U.S. just due to the loss of replacement heifers were estimated to be $125 million per year. Our objective in this study was to evaluate the effect of stillbirth on the dam's subsequent lactation. Data were collected from 20 farms in the U.S.A. (19 from NY, one from IN) from May 2005 until September 2006. Calving-ease scores (scale of 1-5; no problem and extreme difficulty, respectively) and stillbirths were recorded by farm personnel. We used 32,299 calvings for the final analysis where 6.5% of the calvings were stillbirths. The incidence of stillbirths for primiparous cows was 10.7% (of 11,891) and 4% (of 20,408) for multiparous cows. Stillbirth parturition significantly reduced milk production (-1.1 kg/day). The losses in milk production were evaluated in a generalized mixed linear model analysis. The daily milk production for cows with stillbirths was 34.2 kg, compared to 35.3 kg for the cows that had a live calf. Milk-production reduction was greatest early in lactation and declined afterwards. Economic losses from stillbirths include not just the lost calf, the reduced survival, and increased days open but also the decreased milk yield.     

The economy of induced early parturition in New Zealand dairy herds

A breakeven analysis suggests that the economy of inducing cows to calve prematurely is precariously balanced. The analysis is based on data from recent New Zealand publications and on replies to a questionnaire sent to participants in a previously reported induction trial. It suggests that the extra cost per induction is $18.60, that the cost saved is $23.40 and that the income lost $28.80. This implies that extra returns have to be about $24.00 to achieve a nil balance and it is suggested that this might be just possible during the first lactation after induction. Any profit will have to come from advantages beyond the first year. The questionnaire data indicate that about 2/3 of induced cows are likely to provide such advantages, but that 1/3 might cause further losses. It is recommended that the technique of inducing dairy cows to calve prematurely be judiciously employed, mainly in emergency, on young and healthy cows only.     

Bovine tuberculosis and milk production in infected dairy herds in Ireland

This study describes the relationship between bovine tuberculosis (TB) and milk yield in TB-infected dairy herds in Ireland. The study had two objectives: to determine whether cows detected as TB reactors (and thus subject to immediate slaughter) were likely to be the higher milk-producing cows, and to determine whether subclinical TB infection was associated with reduced milk production at or around the time of disclosure (detection). All Irish dairy herds restricted from trading between the 1^st June 2004 and the 31^st May 2005 as a result of two or more TB reactors by the Single Intradermal Comparative Tuberculin Test (SICTT) were considered for study. The data consisted of 419 herds. Data were collected on all TB reactors and a random sample of 5 non-reactor cows in these herds: a data set of 4340 cows (2342 TB reactors and 1998 non-reactors). Previous milk data for the cows were taken into consideration and thus all lactations on a cow were analysed together with the years of lactations. There was an inherent hierarchical structure in the data, with lactations nested within cows and cows within herds and thus a linear mixed model with two random effects was used to describe the data. The results of this study showed that for all lactations and years under investigation, milk yield was significantly lower for TB reactor cows, with differences ranging from 120 kg (2003, lactation 3) to 573 kg (2001, lactation 1), when compared to the non-reactor cows.     

Non-additive effects on milk production in Czech dairy cows

Crossbreeding effects on milk production traits of Czech dual‐purpose and dairy cattle breeds were estimated. Nearly 370 000 cows with known gene proportions from Czech Pied, Ayrshire or Holstein cattle were selected from the national milk recording data base. Single‐trait animal models were calculated for milk, fat and protein yield, fat and protein content. The model of Dickerson including additive, additive maternal, heterotic and recombination effects was used for the part of the animal model describing the crossbreeding effects in all calculations. For milk yield, the additive genetic effect (defined as deviation from Czech Pied cattle) was 850–900 kg for Holstein and 240–480 kg for Ayrshire. The maternal effects were low and negative. Low significant positive heterotic effects were observed being up to approximately 100 kg for Czech Pied × Holstein. The recombination effects were negative and statistically significant for Czech Pied × Holstein. The results for fat and protein yield were similar to the results for milk yield. For fat and protein content, nearly no statistically significant crossbreeding effects were found.     

Effect of paratuberculosis on culling, milk production, and milk quality in dairy herds

OBJECTIVE: To determine the effect of paratuberculosis on culling, milk production, and milk quality in infected dairy herds. DESIGN: Cross-sectional study. ANIMALS: 689 lactating dairy cows in 9 herds. PROCEDURE: Milk, blood, and fecal samples were obtained from all cows. Fecal samples were evaluated via mycobacterial culture. Serum samples were tested with a commercially available ELISA for antibodies against Mycobacterium avium subsp paratuberculosis, and preserved milk samples were tested with an ELISA for antibodies against M paratuberculosis. Mixed effect and proportional hazards models were used to determine the effect of paratuberculosis on 305-day milk, fat, and protein production; somatic cell count linear score; and the risk of culling. RESULTS: Cows with positive results of bacteriologic culture of feces and milk ELISA produced less milk, fat, and protein, compared with herdmates with negative results. No difference in 305-day milk or fat production was detected in cows with positive results of serum ELISA, compared with seronegative cows. The 3 survival analyses revealed that cows with positive results of each test were at higher risk of being culled than cows with negative results. Paratuberculosis status, as determined by use of all 3 diagnostic tests, was not associated with milk somatic cell count linear score. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that for the 9 herds in this study, paratuberculosis significantly decreased milk production and cow longevity.     

Bulk tank milk selenium and its association with milk production parameters in Canadian dairy herds

An observational study was conducted in 63 Canadian dairy farms to evaluate the association of bulk tank milk selenium (Se) concentration (BTSe) with average daily milk yield, milk fat and milk protein, bulk tank somatic cell count (BTSCC), and the probability of being a Staphylococcus aureus-positive herd. Bulk tank milk samples collected between March 2007 and February 2008 were evaluated for BTSCC, S. aureus culture status, and BTSe. Mean BTSe was 0.51 ± 0.15 μmol/L; no herds were classified as deficient or marginal based on BTSe. Bulk tank milk Se was unconditionally associated with milk production; however, adjusting by region indicated a confounding effect of this variable. There was no relationship between BTSe and BTSCC. Higher values of BTSe were associated with lower risk of being a S. aureus-positive herd, possibly as a result of a more robust udder immune response, or as a result of providing Se at a higher rate as one component of an udder health program that reduces risk of being S. aureus positive.     

The effect of ivermectin treatment of late pregnant dairy cows in south-west Victoria on subsequent milk production and reproductive performance

SUMMARY A total of 498 dairy cows in 5 predominantly pasture-fed herds were allocated to pairs. One cow in each pair was treated with a single dose of ivermectin during the dry period. Treated and untreated cows were managed as a single group throughout the trial. Most cows calved between 45 and 115 days after treatment. When data from all herds were pooled, treated cows produced an extra 74 L of milk over the first 100 days of the subsequent lactation (95% confidence interval 20 to 128). Means were greater among treated groups relative to untreated groups in all 5 herds. However, when analysed individually, differences were statistically significant (P < 0.05) in 1 herd only. Over the complete lactation, mean milk volume for treated cows was 86 L greater than for untreated cows (95% confidence interval of difference -57 to 229; P = 0.24). Untreated cows produced 2473 L and 5883 L for the first 100 days of lactation and for the complete lactation, respectively. Milk production responses to treatment did not vary significantly with parity, body condition score, previous production index, calving date category or with plasma pepsinogen concentration or faecal egg count at the time of treatment. Faecal egg counts and plasma pepsinogen concentrations were low at the start of the study. The interval from calving to conception was 4.8 days less in treated cows (95% confidence interval 1.2 to 8.2) relative to untreated cows when data from all 5 herds were pooled. Differences within individual herds were not statistically significant.     

On-farm feeding interventions to increase milk production in lactating dairy cows

Tropical Animal Health and Production - The objective of this study was to investigate the effect of tropical legume (Phaseolus calcaratus) mixed with ruzi grass feeding on the performance of...     

Relationships among milk urea-nitrogen, dietary parameters, and fecal nitrogen in commercial dairy herds

Our study objective was to determine the ability of milk urea-nitrogen concentrations ([MUN]) to predict fecal nitrogen concentrations ([Fecal N]) in commercial dairy herds. A total of 83 dairy herds were each visited 3 times within 48 h after a monthly herd milk test. For each farm visit, forages were sampled for nutrient analyses, which were entered into a computerized ration evaluator, and fecal samples were taken per rectum from each of 6 cows (2 early-, 2 mid-, and 2 late-lactation). Fecal samples were pooled, mixed, and analyzed for nitrogen content. Fecal nitrogen concentrations were compared with the routinely measured nutritional parameters from the ration evaluation, and the herd average [MUN] for the previous milk test date using mixed linear regression analyses. Total protein supplied in the ration was significantly positively associated with [Fecal N], but herd average [MUN] was not associated (P > 0.10) with [Fecal N].     

Fenbendazole-related drug residues in milk from treated dairy cows

Oral administration of [¹⁴C] fenbendazole (FBZ) at a dose of 5.Omg/kg leads to the presence of radiolabel in the milk of lactating dairy cows. However, the maximum mean concentration of total FBZ equivalents quantitated to one-third of the recommended safe concentration in milk (1.67 μg/mL). The label is equally distributed to the fat and aqueous portions of the milk. The maximum level, in general, is attained approximately 24-36 h after drug administration, with the highest levels ranging from 24 to 48 h after administration. The residues rapidly deplete, attaining levels of 10-20ng/mL by day 5, and are essentially undetectable by radiolabel monitoring by day 6. Extraction of the milk by matrix solid phase dispersion indicated that the label was distributed between traces of the parent drug, FBZ, and predominantly, the FBZ sulphoxide (SO) and sulphone (SO₂) metabolites. No other radiolabelled peaks were observed. Based on these data the metabolites of FBZ, FBZ-sulphone and FBZ-sulphoxide, could be used as marker residues for monitoring the administration of FBZ to lactating dairy cows.     

Licking induced changes to the pattern of moxidectin milk elimination after topical treatment in dairy cows

Pour-on administration of the macrocyclic lactones anti-parasitic compounds in beef and dairy cattle is now worldwide accepted. However, the information available on their milk excretion pattern, after topical administration is rather limited. Additionally, the cattle licking behaviour has been proven to affect the kinetics of these anti-parasitic compounds. The purpose of this study was to investigate the influence of the natural licking behaviour on the plasma and milk disposition of moxidectin (MXD), topically administered (500 μg/kg) in lactating dairy cows. Ten lactating Holstein dairy cows (705 kg body weight) were allocated into two experimental groups ( n  = 5). The licking was prevented during 5 days postadministration in animals in group I, and the remaining cows (group II) were allowed to lick freely. MXD concentrations profiles were measured in plasma and milk over 15 days posttreatment. The licking restriction period caused marked changes in MXD disposition kinetics both in plasma and milk. Both plasma and milk MXD concentrations (partial AUC 0–5 days) were significantly lower ( P  < 0.05) in licking-restricted cows. After the 5-day of restriction period, the animals were allowed to lick freely, which permitted the oral ingestion of MXD, situation clearly reflected both in plasma profile and milk excretion pattern. Despite the enhanced MXD milk concentrations measured in free-licking cows, drug concentrations did not reach the maximum MXD residues limit.     

Induction of parturition in dairy cows with dexamethasone.

Sixty Holstein cows were paired by parity and sire, and one of each pair was allocated at random to treatment or control; 17 cows were injected with 7.5 mg/100 kg dexamethasone trioxa undecanoate 14 days before the predicted date of calving, 13 cows received the same dose five days before term and 30 cows were left untreated. The treatment significantly advanced parturition and 29 of the 30 induced cows calved within 72 hours of the injection. Induction at day 14 before term was safe for calf and dam, the calves were 3.2 kg lighter than control calves and there was a high incidence of retained placenta. Treatment for this condition resulted in increased veterinary costs of 14.50 pounds per cow exclusive of dexamethasone treatment. Treatment at this stage was also associated with low pregnancy rates in the next breeding season. Calves born after induction at five days before term were not significantly lighter than calves from control cows, the problem of retained placenta was less marked and there were no subsequent effects on fertility. There were no significant effects of induction on milk yield or milk quality up to 200 days of lactation.