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Objective—To determine association between exposure to Neospora caninum and milk production in dairy cows.
Design—Prospective observational study.
Animals—565 Holstein cows.
Procedure—Cows were classified as seropositive or seronegative to N caninum within 7 days after calving by use of a kinetic ELISA. Milk production was compared between seropositive and seronegative cows.
Results—On the basis of 305-day mature equivalent milk production data, seropositive cows produced less milk (2.8 lb/cow per day) than did seronegative cows. In addition, analysis of results throughout the first 300 days of lactation revealed that after adjusting for effects of lactation number, calving season, clinical mastitis, and lameness, milk weight of seropositive cows was 2.5 lb/cow per day less than that of seronegative cows.
Conclusions and Clinical Relevance—Exposure to N caninum was associated with a 3 to 4% decrease in milk production. A decrease in milk production of 800 lb/cow for a typical 305-day lactation represents a loss of $128/cow. (J Am Vet Med Assoc 2001; 219:632–635)
Objective—To examine the relationship between exposure to Neospora caninum and abortion in dairy cows during their first, second, third, and fourth or later lactations and to establish the main mode of transmission in female calves from birth until their first pregnancy was terminated by abortion or parturition.
Design—Prospective observational study.
Animals—460 Holstein cows and 79 female calves.
Procedure—Cows were classified as seropositive or seronegative to N caninum within 7 days after calving; incidence of abortion was compared between groups during different lactations. Blood samples were collected from female calves before ingestion of colostrum and every 6 months until their first pregnancy was terminated by abortion or parturition; number of seropositive calves was compared between seropositive and seronegative dams.
Results—During the first pregnancy of their second lactation, risk of abortion for seropositive cows was 2.8 times that of seronegative cows. Among 10 calves born to seropositive cows, 4 were classified as seropositive at birth and thereafter. Among 69 calves born to seronegative cows, all were classified as seronegative at birth; 67 calves remained seronegative thereafter.
Conclusions and Clinical Relevance—Exposure to N caninum alone was not significantly associated with abortion in cows during the first, third, and fourth or later lactations. Seropositive cows that have aborted previously may have subsequent abortions attributable to N caninum. Congenital infection was the main mode of N caninum transmission in a cohort of female calves. (J Am Vet Med Assoc 2002;221:1742–1746)
Objective—To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition.
Animals—152 Holstein cows that calved during October through December of 1997.
Procedure—All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM.
Results—Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of ≥ 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of ≥ 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia.
Conclusions and Clinical Relevance—In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship. (Am J Vet Res 2004;65:1071–1076)
Objective—To determine the effect of a controlled-release monensin capsule administered at cessation of lactation on incidence of calving-related disorders, fertility, and milk yield in dairy cows.
Animals—290 dairy cows treated with monensin and 290 untreated control cows.
Procedure—Treated cows received a capsule that released monensin at 335 mg/d for 95 days. Incidence of calving-related disorders; daily milk yield up to 20 days postpartum; test-day milk yield, fat, protein, and mature-equivalent 305-day milk production; and body condition score at calving were determined. Reproductive variables were conception rate at first service, pregnancy rate, and calving-to-conception interval.
Results—Cows treated with monensin were 2.1 times as likely to develop dystocia and 0.8 times as likely to develop metritis as control cows. For milk yield, there was an interaction of treatment ×time ×parity. In multiparous cows, monensin significantly improved milk yield at test days 4 and 7. In addition, monensin increased body condition score at calving.
Conclusions and Clinical Relevance—Despite increasing the likelihood of developing dystocia and metritis, administration of monensin improved the lactational performance of multiparous cows and may be a promising additive for use at the time of cessation of lactation.
OBJECTIVE To identify milk component alterations that might be useful for detecting cows with rumen indigestion.
DESIGN Prospective case-control study.
ANIMALS 23 Holstein cows with rumen indigestion (cases) and 33 healthy cohorts (controls) from 1 herd.
PROCEDURES Cases were defined as cows between 30 and 300 days postpartum with a > 10% decrease in milk yield for 2 consecutive milkings or > 20% decrease in milk yield from the 10-day rolling mean during any milking, abnormally decreased rumen motility, and no other abnormalities. Each case was matched with 2 healthy cows (controls) on the basis of pen, parity, days postpartum, and mean milk yield. Some cows were controls for multiple cases. All cows underwent a physical examination and collection of a rumen fluid sample for pH measurement at study enrollment. Individual-cow milk yield and milk component data were obtained for the 16 milkings before and after study enrollment. Rumen motility and pH and milk components were compared between cases and controls.
RESULTS Rumen motility for cases was decreased from that of controls. Cases had an abrupt increase in milk fat percentage and the milk fat-to-lactose ratio during the 2 milkings immediately before diagnosis of rumen indigestion. Receiver operating characteristic analyses revealed that a 10% increase in the milk fat-to-lactose ratio had the highest combined sensitivity (57%) and specificity (85%) for identifying cows with rumen indigestion.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a positive deviation in the milk fat-to-lactose ratio might be useful for identifying cows with rumen indigestion.