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administration at clinically relevant doses in dairy cattle. 6 For both drugs, milk concentrations depleted to concentrations that were below 10 ng/mL after 3 days following single oral doses. 6 The effect of lactation on the pharmacokinetics has been

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in Journal of the American Veterinary Medical Association

lameness in the subsequent lactation by use of information available during hoof trimming at the cessation of lactation in dairy cows. The hypothesis was that DCT, BCS, age, and CHDLs at cessation of lactation are associated with the incidence of sole

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in American Journal of Veterinary Research

the value of milk production, dependent on cow traits, stage of lactation, current milk price, cost of replacements, labor, and veterinary care. 3–5 At 2010 milk prices, that cost is upward of $1.9 billion. 6 It is estimated that 70% to 80% of this

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in Journal of the American Veterinary Medical Association

procedures are performed in cows at the end of lactation to reduce the incidence of lameness (which is known to be highest during the early stages of lactation) 6,13,14 during the following lactation. Overgrowth of the hoof horn capsule can lead to incorrect

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in Journal of the American Veterinary Medical Association

Objective—

To determine whether lactation length was associated with reproductive performance or longevity of sows.

Design—

Cohort study.

Sample Population—

Data collected between 1986 and 1992 for sows in 15 breeding herds in Minnesota and Iowa.

Procedure—

Sows were grouped into 4 genetic line categories according to their sources and 6 parity categories (1, 2, 3, 4, 5 or 6, and ≥ 7). Multivariate regression analysis of reproductive performance was conducted, using the general linear model procedure. Logistic regression was conducted with a dichotomous response variable for sow longevity (ie, removal from or retention in the herds). Odds ratios were obtained from estimated coefficients of the regression.

Results—

Herd, genetic line, parity, year, month, and lactation length were significant in statistical models for litter (eg, number of live pigs/litter) and interval (eg, weaning-to-mating interval) traits. Interactions between lactation length and year, lactation length and genetic line, lactation length and parity, and lactation length and genetic line and parity were also significant. Sows removed from herds had a significantly shorter lactation length than did sows of the same parity that were retained in the herds. Sows that had shorter lactation lengths were at higher risk of being removed from the herds than were those that had longer lactation lengths.

Clinical Implications—

Lactation length is associated with reproductive performance and longevity, but genetic line and parity playa role as well. Thus, attention should be paid to genetic lines and parity of sows in the herd when implementing an early weaning production practice. (J Am Vet Med Assoc 1997;210:935–938)

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in Journal of the American Veterinary Medical Association

Cows —Thirty-three multiparous Holstein dairy cows at 20 to 25 days of lactation were evaluated. Cows from a herd of approximately 110 cattle at the Eastern Tennessee Research and Education Center Dairy Unit were studied. Experimental design —Cows

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in American Journal of Veterinary Research

A first-lactation Holstein cow was submitted to the Utah Veterinary Diagnostic Laboratory on July 18, 2006, because of swelling of the carpal joints, diffuse subcutaneous edema extending from the carpal to metacarpophalangeal joints, and forelimb

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in Journal of the American Veterinary Medical Association

, stress (eg, Cesarean section), premature parturition, or undernourishment of a bitch may lead to insufficient milk yield. 3 Certain drugs or hormones (eg, slow-release deslorelin implants or cabergoline) administered during pregnancy or lactation may

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate changes in protein and nutrient composition of milk throughout lactation in dogs.

Sample Population—Milk samples collected from 10 lactating Beagles.

Procedure—Milk samples were collected on days 1, 3, 7, 14, 21, 28, 35, and 42 after parturition and analyzed to determine concentrations of nitrogen, nonprotein nitrogen, casein, whey proteins, amino acids, lipids, lactose, citrate, minerals, and trace elements. Optimum conditions for separating casein from whey proteins and distribution of milk proteins throughout lactation were assessed by use of polyacrylamide gel electrophoresis.

Results—Protein concentration was high in samples collected on day 1 (143 g/L), decreased through day 21 (68.4 g/L), and increased thereafter. Concentration of nonprotein nitrogen did not change throughout lactation (5.7 to 9.9% of total nitrogen content). Casein-towhey ratio was approximately 70:30 and remained constant throughout lactation. Lactose concentration increased from 16.6 g/L on day 1 to 34.0 to 40.2 g/L on days 7 to 42. Lipid concentration ranged from 112.5 to 137.2 g/L. Citrate concentration increased from day 1 (4.8 mM) to day 7 (6.6 mM), then gradually decreased until day 42 (3.9 mM). Iron, zinc, copper, and magnesium concentrations decreased during lactation, whereas calcium and phosphorus concentrations increased. Calcium-to-phosphorus ratio remained constant throughout lactation (approx 1.6:1). Energy content of milk ranged from 1,444 to 1,831 kcal/L.

Conclusions and Clinical Relevance—Protein and nutrient composition of milk changes throughout lactation in dogs. These data can provide valuable information for use in establishing nutrient requirements of puppies during the suckling period. (Am J Vet Res 2001;62:1266–1272)

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in American Journal of Veterinary Research

Objective—

To determine whether treating cows with antimicrobials at the end of lactation would lower the incidence of clinical mastitis, improve milk production, and decrease somatic cell count (SCC) in the subsequent lactation.

Design—

Randomized blind field trial.

Animals—

233 Holstein cows from a single herd. All cows were in lactation 2 or greater.

Procedure—

Cows were randomly assigned to treatment groups. Treated cows were given procaine penicillin G and novobiocin by intramammary infusion. Control cows were not treated. Farm personnel recorded cases of clinical mastitis. Milk yield and SCC were recorded during the subsequent lactation.

Results—

Treatment did not significantly reduce the incidence of clinical mastitis when data for all cows were grouped or when data were stratified by lactation groups (lactation 2 vs lactation ≥ 3) or by last SCC (≤ 500,000 cells/ml vs > 500,000 cells/ml). Somatic cell counts (first, mean of first 5, maximum of first 5) for treated and control cows were similar, and proportions of treated and control cows with SCC > 500,000 cells/ml at least once were not significantly different. Treated cows produced 179 kg (394 lb) more milk during the first 17 weeks of lactation than did control cows.

Clinical Implications—

Treating cows with antimicrobials at the end of lactation increased 17-week milk production during the subsequent lactation and, at current milk prices, was financially preferable to not treating them. (J Am Vet Med Assoc 1997;211:207–211)

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in Journal of the American Veterinary Medical Association