RESUMO
Poor udder health status can have a detrimental effect on milk yield and reproductive performance, leading to reductions in the dairy farm profit. The objective of this retrospective longitudinal study was to assess the associations of somatic cell count (SCC) with daily milk yield and reproductive performance. A database with 1,930,376 lactations from 867 Argentinean grazing dairy herds records collected for 14 years was used. The association of the evolution of SCC (healthy vs. new case vs. cured vs. chronic; with 150,000 SCC/mL as threshold) and of the severity of SCC [mild (150,000--400,000 SCC/mL) vs. moderate (400,000-1,000,000 SCC/mL) vs. severe (>1,000,000 SCC/mL)] with the odds for conception were estimated. Finally, the associations of the linear score of SCC (LS-SCC) with daily milk yield were estimated depending on parity and milk production quartile. The odds ratios (CI 95%) for conception at first service were 0.921 (0.902-0.941), 0.866 (0.848-0.884), and 0.842 (0.826-0.859) for the new case, cured, and chronic cows compared with healthy cows, respectively. Also, the odds ratios (CI 95%) for conception were 0.902 (0.881-0.925), 0.837 (0.808-0.866) and 0.709 (0.683-0.736) for mild, moderate and severe cases compared with healthy cows, respectively. An increase of one point of LS-SCC was associated with decreases of 0.349, 0.539, and 0.676 kg in daily milk yield for first-, second-, and third-lactation cows, respectively. In conclusion, SCC is negatively associated with the risk for conception and with daily milk yield in grazing dairy cows. This negative relationship with conception is higher when SCC increase occurs after the service date and it is influenced by severity of mastitis, and in the case of milk yield, the negative association is influenced by parity, milk production quartile, and severity of mastitis.
Assuntos
Doenças dos Bovinos , Mastite Bovina , Animais , Bovinos , Contagem de Células/veterinária , Indústria de Laticínios , Feminino , Lactação , Estudos Longitudinais , Leite , Gravidez , Estudos RetrospectivosRESUMO
The objective of the present study was to assess the relationship between individual cow milk yield and fertility, accounting for the contextual effect of the herd. A data set including 657,968 lactations from 677 dairy herds in Argentina from 2001 to 2012 was used. The odds of pregnancy by 100 d in milk (DIM) were assessed by a multilevel logistic model (with cow as the first and herd as the second hierarchical level), and time to pregnancy was assessed by a proportional hazards regression model. Multilevel logistic models included the fixed effects of milk yield by 80 DIM, parity, year, and calving season at cow level and quartiles of herd milk yield by 80 DIM as a contextual effect. The proportional hazards model included the effect of daily cow-level milk yield as time-dependent variable, with milk yield at herd level as the stratification variable. Cows producing 1 standard deviation over the mean milk yield of their herd had 1.3 percentage point lower pregnancy by 100 DIM (from 31.4 to 30.1%; odds ratio = 0.942) when in herds in the top quartile of milk yield, whereas they increased 0.5 percentage points (from 27.9 to 28.4%) when in herds in the lowest quartile of milk yield. Only 4% of the observed variation in pregnancy by 100 DIM was explained by the random effect of the herd. Similarly, cows producing 1 standard deviation (8 kg/d) greater than the herd mean daily milk had 1.3% lower hazard of pregnancy (hazard ratio = 0.987) at 63 DIM in herds in the top quartile of milk yield, whereas they had 14.8% higher hazard (hazard ratio = 1.148) in herds in the lowest quartile of milk yield. The magnitude of the negative association between the cow's daily milk yield and the hazard of pregnancy increased with DIM. In conclusion, the relationship between milk yield and reproductive performance is statistically significant, but the effect size is practically small and is modulated by herd production level.
Assuntos
Bovinos/fisiologia , Indústria de Laticínios , Lactação/fisiologia , Reprodução/fisiologia , Animais , Argentina , Feminino , Leite , GravidezRESUMO
AIMS: To determine the effect of providing water within the area grazed by dairy cows on milk yield and quality, compared to requiring cows to walk to a distant water trough, on a dairy farm in the Pampa region of Argentina during summer. METHODS: Holstein dairy cows were allocated to two herds with similar parity, days in milk and milk production. They were grazed in one paddock that was divided in two, with a fixed water trough at one end. Cows were moved twice daily to grazing plots within the paddock. Control cows (n=66) could only access water from the fixed trough, whereas supplemented cows (n=67) also received water from a mobile trough within the grazing plot. Milk production of each cow, and water consumption of the two herds were measured daily over 62 days. Milk composition for each herd was determined weekly from Days 18 to 60 of the study, and grazing behaviour was observed between 08:00 and 16:00 hours on Days 11-15, 19-22 and 39-43. RESULTS: Over the 62 days of the study, supplemented cows produced 1.39 (SE 0.11) L/cow/day more milk than Control cows (p=0.027). Estimated mean daily water intake was 50.4 (SE 2.1) L/cow/day for supplemented cows and 58.2 (SE 2.7) L/cow/day for Control cows (p=0.004). Percentage total solids in milk was higher for supplemented (12.5 (SE 0.06)%) than Control (12.4 (SE 0.04)%) cows (p=0.047). During the periods of behavioural observation, a higher percentage of cows in the water supplemented than the Control herd were observed in the grazing area (p=0.012). CONCLUSIONS AND CLINICAL RELEVANCE: This preliminary study demonstrated that provision of water to dairy cows within the grazing plot was beneficial for milk production and composition, and may be associated with longer periods spent within the grazing area, during hot weather in the Pampa region of Argentina.
Assuntos
Bovinos/fisiologia , Água Potável , Lactação/fisiologia , Leite/fisiologia , Animais , Argentina , Indústria de Laticínios , Suplementos Nutricionais , FemininoRESUMO
The objectives of this study were to assess the association of a 4-point scale of vaginal discharge score (VDS) with time to pregnancy to define criteria for a practical case of purulent vaginal discharge (PVD) in dairy cows, to test the risk factors for PVD, and, finally, the effect of a dose of PGF2α on cure and reproductive performance. In experiment 1, grazing Holstein cows (n = 2,414) had their vaginal discharge scored at â¼32 d in milk (DIM) on a 4-point scale, the effect of VDS on the hazard of pregnancy by 300 DIM was then assessed to derive a case definition of PVD. Risk factors for PVD and self-cure were also assessed. In experiment 2, grazing Holstein cows (n = 6,326) from 5 herds were checked for PVD at â¼30 DIM. Cows with PVD were assigned to receive one dose of 500 µg of PGF2α analog (Cloprostenol; Ciclase, Syntex SA, Buenos Aires, Argentina) per cow (odd ear tag number) or to remain untreated (even tag number). Cure was declared if cows presented clear normal vaginal discharge (VDS-0) at visit 2 (â¼62 DIM). Data were analyzed with Cox's regression and mixed logistic models. In experiment 1, cows with VDS ≥1 had lower hazard of pregnancy and longer calving to pregnancy interval than cows with VDS-0. This finding was not affected by the time at which the diagnosis was performed. Therefore, a cow ≥21 DIM and having VDS ≥1 was used to define a case of PVD. The odds of PVD were greater in primiparous cows compared with multiparous, in cows with abnormal calving compared with those with normal calving, and in those losing BCS peripartum. In experiment 2, PGF2α treatment tended to slightly increase the hazard of pregnancy (adjusted hazard ratio = 1.13). Conversely, PGF2α had no effect on the odds of cure of PVD [adjusted odds ratio (AOR) = 1.19], pregnancy at first service (AOR = 1.03), or pregnancy by 100 DIM (AOR = 0.89) or 200 DIM (AOR = 1.27). In conclusion, cows with VDS ≥1 can be considered to have PVD because of their lower hazard of pregnancy and longer calving to pregnancy interval (up to 48 d). Important risk factors are parity, calving, and body condition score loss peripartum. Optimal time of diagnosis is ≥28 to 35 DIM because cows experience a high self-cure rate. Self-cure is also affected by parity, prepartum BCS, and VDS. Finally, as treatment with one dose of PGF2α had a small effect on the hazard of pregnancy and no effect on clinical cure, its therapeutic use in grazing dairy cows with PVD is not recommended.
Assuntos
Dinoprosta/uso terapêutico , Endometrite/veterinária , Animais , Bovinos , Doenças dos Bovinos/diagnóstico , Feminino , Fatores de Risco , Descarga Vaginal/veterináriaRESUMO
Mammary ductal morphogenesis during prepuberty occurs mainly in response to insulin-like growth factor-1 (IGF-1) and estradiol stimulation. Dairy heifers infected with gastrointestinal nematodes have reduced IGF-1 levels, accompanied by reduced growth rate, delayed puberty onset, and lower parenchyma-stroma relationship in their mammary glands. Immunohistochemical studies were undertaken to determine variations in cell division rate, IGF-1 system components, and estradiol receptors (ESR) during peripubertal development in the mammary glands of antiparasitic-treated and untreated Holstein heifers naturally infected with gastrointestinal nematodes. Mammary biopsies were taken at 20, 30, 40, and 70 wk of age. Proliferating cell nuclear antigen immunolabeling, evident in nuclei, tended to be higher in the parenchyma of the glands from treated heifers than in those from untreated. Insulin-like growth factor binding proteins (IGFBP) type 2 and type 3 immunolabeling was cytoplasmic and was evident in stroma and parenchyma. The IGFBP2-labeled area was lower in treated than in untreated heifers. In the treated group, a maximal expression of this protein was seen at 40 wk of age, whereas in the untreated group the labeling remained constant. No differences were observed for IGFBP3 between treatment groups or during development. Immunolabeling for α ESR (ESR1) was evident in parenchymal nuclei and was higher in treated than in untreated heifers. In the treated group, ESR1 peaked at 30 wk of age and then decreased. These results demonstrate that the parasite burden in young heifers negatively influence mammary gland development, affecting cell division rate and parameters related to estradiol and IGF-1 signaling in the gland.
Assuntos
Proliferação de Células , Receptor alfa de Estrogênio/metabolismo , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Glândulas Mamárias Animais/metabolismo , Infecções por Nematoides/veterinária , Animais , Anti-Helmínticos/farmacologia , Bovinos/parasitologia , Estradiol/metabolismo , Receptor alfa de Estrogênio/genética , Feminino , Fenbendazol/farmacologia , Trato Gastrointestinal/parasitologia , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Ivermectina/farmacologia , Levamisol/farmacologia , Glândulas Mamárias Animais/citologia , Nematoides , Transdução de SinaisRESUMO
The objectives of this study were to assess the risk factors for metritis, its effects on milk yield and on reproductive performance, and the efficacy of ceftiofur therapy in Holstein dairy cows. Cows (n=303) from a commercial dairy herd in Argentina were studied. Cows were scored for body condition, and blood samples were collected on d -14, 7, 21, 31, 41, and 50 relative to parturition. Cows having a watery, purulent, or brown, and fetid vaginal discharge (VD) and rectal temperature ≤ 39.2°C were diagnosed as having clinical metritis, and those having a similar VD and rectal temperature >39.2°C were diagnosed as having puerperal metritis. Both clinical and puerperal metritis cows were randomly assigned to control (no treatment) or ceftiofur group (2.2mg/kg×3 consecutive days). Cure was declared if clear VD was observed at 21 d in milk (DIM). Blood samples were analyzed for nonesterified fatty acids, ß-hydroxybutyrate, and blood urea nitrogen using commercial kits, and for insulin-like growth factor-1, insulin, and leptin by RIA. Data were analyzed with PROC MIXED, GENMOD, PHREG, and LIFETEST from SAS (SAS Institute Inc., Cary, NC). The risk for metritis increased with dystocia, retained fetal membranes, and dead calf [AOR (adjusted odds ratio)=2.58, 95% CI: 1.189-5.559], and as prepartum nonesterified fatty acids levels increased (AOR=1.001, 95% CI: 0.999-1.002). Conversely, risk decreased as prepartum insulin-like growth factor-1 increased (AOR=0.65, 95% CI: 0.349-1.219). Cows having either clinical or puerperal metritis produced less milk by 90 DIM than did healthy cows (2,236 ± 172 vs. 2,367 ± 77 vs. 2,647 ± 82 kg, respectively). Cows with puerperal metritis had lower risk for pregnancy by 100 DIM (AOR=0.189, 95% CI: 0.070-0.479) and a lower hazard rate for pregnancy by 150 DIM (hazard rate: 0.753, 95% CI: 0.621-0.911), and took longer to get pregnant (129 vs. 111 vs. 109 d, for puerperal metritis, clinical metritis, and healthy cows, respectively). Ceftiofur treatment was not associated with cure rate or milk yield but was related to increased risk for pregnancy at timed artificial insemination (AOR=2.688, 95% CI: 0.687-10.832), and for lower risk of reproductive cull (AOR=0.121, 95% CI: 0.014-1.066). In conclusion, abnormal calving and negative energy balance are associated with increased risk for metritis. Metritis, especially puerperal metritis, correlates with reduced milk production and poor reproductive performance. Finally, the likelihood for having a normal VD (indicative of cure) increased 2.6% for every day of increase in postpartum time and was 2 times higher for cows with clinical metritis than for those with puerperal metritis.
Assuntos
Doenças dos Bovinos/diagnóstico , Endometrite/veterinária , Reprodução , Animais , Antibacterianos/uso terapêutico , Argentina , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Doenças dos Bovinos/fisiopatologia , Cefalosporinas/uso terapêutico , Indústria de Laticínios , Endometrite/diagnóstico , Endometrite/tratamento farmacológico , Feminino , Lactação , Gravidez , Infecção Puerperal/diagnóstico , Infecção Puerperal/veterinária , Fatores de Risco , Descarga VaginalRESUMO
The objectives of this study were to assess the clinical and metabolic risk factors for clinical endometritis, the likelihood for having a normal vaginal discharge during postpartum, and the effects of endometritis on milk yield, reproductive efficiency, and metabolic status in Holstein cows. The study was conducted in a commercial dairy herd (Cordoba, Argentina) where 303 Holstein cows were enrolled. Cows were body condition scored (1 to 5) and tail bled on -14, 7, 21, 31, 41, and 50 d relative to parturition. Cows having a vaginal discharge with presence of pus between 21 and 41 d postpartum (dpp) were diagnosed as having clinical endometritis. Plasma blood samples were analyzed for nonesterified fatty acids (NEFA), ß-hydroxybutyrate (BHBA), and blood urea nitrogen using commercial kits and insulin-like growth factor 1, insulin, and leptin by RIA. Data were analyzed with PROC MIXED, PROC GENMOD, and PROC PHREG of SAS (SAS Institute Inc., Cary, NC). Abnormal calving and puerperal metritis increased the risk for endometritis [adjusted odds ratio (AOR)=2.21 for both]. High prepartum NEFA and high postpartum BHBA increased the risk for endometritis (AOR=1.003 and 1.001, respectively), whereas high prepartum blood urea nitrogen reduced it (AOR=0.853). Cut-offs of 456.6 µM NEFA and 402.5 µM BHBA had sensitivities of 0.69 and 0.58, and specificities of 0.88 and 0.86, respectively. The likelihood for having normal vaginal discharge increased with time (â¼1% × dpp) and with normal calving. Cows with endometritis had higher milk yield than normal herdmates (27.8±0.9 vs. 25.7±0.4 kg/d), lower risk for pregnancy by 100 dpp (AOR=0.10), higher nonpregnancy risk by 200 dpp (AOR=2.87), and higher risk for culling than normal cows (AOR=2.28). Cows with endometritis had a lower hazard rate (0.44) for pregnancy and had approximately 70 d longer calving-to-conception intervals. Finally, endometritis had no effect on metabolic hormones. In conclusion, the risk for clinical endometritis increases with abnormal calving and puerperal metritis, as prepartum NEFA and postpartum BHBA concentrations increase. Prepartum NEFA and postpartum BHBA could be useful for the prediction of endometritis. Last, clinical endometritis has detrimental effects on reproductive efficiency, as affected cows take longer to get pregnant and are at higher risk for culling.
Assuntos
Doenças dos Bovinos/etiologia , Endometrite/veterinária , Ácido 3-Hidroxibutírico/sangue , Animais , Argentina , Nitrogênio da Ureia Sanguínea , Bovinos , Doenças dos Bovinos/metabolismo , Doenças dos Bovinos/fisiopatologia , Endometrite/etiologia , Endometrite/metabolismo , Endometrite/fisiopatologia , Ácidos Graxos não Esterificados/sangue , Feminino , Insulina/sangue , Fator de Crescimento Insulin-Like I/análise , Lactação/fisiologia , Leptina/sangue , Gravidez , Reprodução/fisiologia , Fatores de RiscoRESUMO
Development of resistance to anthelmintic drugs has motivated the search for diagnostic methods to identify animals for targeted selective treatments. We compared three methods for the diagnosis of nematode infection in relation to milk production in a fully grazing dairy herd of 150 cows in the humid Pampa (Argentina). Animals had feces, blood and milk sampled during the first postpartum month for EPG, pepsinogen and anti-Ostertagia antibody determination, respectively. With the results obtained two groups of cows, divided in high and low parasite burden, were conformed for each method, and milk production was then compared between groups. When cows were separated by the EPG method (EPG=0 (N=106) vs. EPG>0 (N=44)) a difference of nearly 800 l of milk per cow per lactation was found (P<0.05). On the other hand, milk production between groups separated by Pepsinogen (mUtyr ≤ 1000 vs. mUtyr > 1000) or by anti-Ostertagia (ODR ≤ 0.5 vs. ODR > 0.5) results did not differ. Interestingly, proportion of cows in each group differed between methods (P<0.0001), and the anti-Ostertagia method yielded significantly more cows in the high index group compared to results using the EPG or Pepsinogen method. No correlations were found between parasite indexes determined by the different methods. High parasite burden estimation found may be ascribed to the production system, fully grazing all year round, and to the sampling time, at the beginning of lactation with cows in negative energy balance and depressed immunity. The fact that the cows were born and reared outside, on pasture with continuous nematode larvae exposure, may also account for the results obtained. In conclusion, EPG counting during the first postpartum month may be a useful tool for the diagnosis of production impairment induced by high nematode burden in adult grazing dairy cows. The anthelmintic treatment of only the EPG-positive recently calved cows would improve milk production, while reducing selective pressure on nematode population for the development of resistance.
Assuntos
Doenças dos Bovinos/diagnóstico , Gastroenteropatias/veterinária , Lactação , Nematoides/imunologia , Infecções por Nematoides/veterinária , Animais , Anticorpos Anti-Helmínticos/sangue , Argentina , Bovinos , Doenças dos Bovinos/metabolismo , Doenças dos Bovinos/parasitologia , Indústria de Laticínios/métodos , Fezes/parasitologia , Feminino , Gastroenteropatias/diagnóstico , Gastroenteropatias/metabolismo , Gastroenteropatias/parasitologia , Nematoides/isolamento & purificação , Infecções por Nematoides/diagnóstico , Infecções por Nematoides/metabolismo , Ostertagia/imunologia , Ostertagia/isolamento & purificação , Ostertagíase/diagnóstico , Ostertagíase/parasitologia , Ostertagíase/veterinária , Contagem de Ovos de Parasitas/veterinária , Carga Parasitária/veterinária , Pepsinogênios/sangueRESUMO
Parasitism in cattle is known to impair growth and development. Recent findings suggest that productivity of adult animals is also affected, but little is known about the physiological mechanisms involved. Furthermore, development of nematode resistance to drugs makes imperative the search of management practices that avoid whole herd treatment. We undertook an epidemiological and endocrine study in a grass based dairy farm in Argentina to study the effect of parasites on milk production and the underlying mechanisms involved, and identify individual animals that would benefit from antiparasitic treatment. All the cows in the dairy were followed monthly for egg parasite output in feces. Samples were cultured for genera determination. Milk production and reproductive results were recorded and periodical bleedings for hormone determination were performed. Nematode egg output (EPG) was maximal in late Summer and Autumn and minimal in Spring in coincidence with the Ostertagia inhibition-disinhibition cycle as this genus had the highest prevalence in all the study. The highest proportion of positive samples was found in the high producing herd and maximal counts were found in the peripartal period. Milk production did not correlate with EPG mean values but, when cows were grouped by EPG positivity around parturition, a significant difference in total milk production between EPG null and positive cows was observed. Positive cows produced 7%, 12% or 15% less milk than null EPG cows, depending on the sampling month/s chosen for classification. The highest difference was seen when both prepartum and postpartum samples were taken into account. No difference in lactation length and a marginal effect on partum to first service interval were encountered. Endocrine studies revealed a decrease in serum growth hormone (GH), type I insulin-like growth factor (IGF-I) and prolactin during lactation in cows with positive EPG in the first postpartum sample with respect to null EPG cows at that time. GH levels decreased and prolactin and IGF-I levels increased in both groups of cows from month 0 to 6 in milk. Serum insulin levels remained stable throughout lactation and were similar in both groups of cows. In conclusion, EPG around parturition may be a useful tool for identifying cows that will have a decrease in productivity due to parasite effects and would possibly benefit from an antiparasitic treatment. Besides, our results suggest that detrimental effect of parasites on milk production may be mediated by GH, IGF-I and prolactin serum levels.
Assuntos
Doenças dos Bovinos/metabolismo , Doenças dos Bovinos/parasitologia , Gastroenteropatias/veterinária , Leite/metabolismo , Nematoides/metabolismo , Infecções por Nematoides/veterinária , Animais , Argentina , Bovinos , Distribuição de Qui-Quadrado , Fezes/parasitologia , Feminino , Gastroenteropatias/metabolismo , Gastroenteropatias/parasitologia , Hormônio do Crescimento/sangue , Hormônio do Crescimento/metabolismo , Insulina/sangue , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/líquido cefalorraquidiano , Fator de Crescimento Insulin-Like I/metabolismo , Lactação , Infecções por Nematoides/metabolismo , Infecções por Nematoides/parasitologia , Contagem de Ovos de Parasitas/veterinária , Período Periparto , Prolactina/sangue , Prolactina/metabolismo , Estações do AnoRESUMO
Female Holstein calves were treated with ivermectin from birth to first oestrus to study the effect of parasitic burden and anthelmintic treatment on reproductive and productive performance. First oestrus, age at first service and age at calving were advanced by 30, 70 and 110 days, respectively (P<0.05), in ivermectin-treated animals compared with controls. No significant differences were observed in the conception rate, the number of services and the characteristics of the newborn calves and any problems at calving between the two groups. Daily milk yield, fat content in milk during first lactation, and the concentrations of growth hormone, insulin-like growth factor type 1, insulin and prolactin in serum were similar in both groups of cows. Culling during the first lactation was more common in untreated (47 per cent) than in treated (11 per cent) cows (P<0.05).