The objective of this study was to evaluate the efficacy of intramammary treatment with ceftiofur hydrochloride of nonsevere, clinical coliform mastitis. One hundred four cases on 5 farms met the enrollment criteria for the study. Escherichia coli was the most common coliform species identified in milk samples from cows with mild to moderate clinical mastitis, followed by Klebsiella spp. and Enterobacter spp. At enrollment, a milk sample from the affected quarter was taken and used for on-farm culture or submitted to the laboratory. For cows in the treatment group, treatment was initiated with ceftiofur hydrochloride via intramammary infusion at 24-h intervals for 5 d according to label standards. Cows in the control group did not receive treatment. Culture results were available on the day after enrollment and only cows with coliform mastitis continued in the treatment and untreated control groups. Bacteriological cure was defined based on 2 posttreatment milk samples. Molecular typing was used for final definition of bacteriological cure. Treatment of nonsevere clinical gram-negative mastitis with ceftiofur hydrochloride resulted in a significant increase in bacteriological cure compared with nontreated controls in animals infected with E. coli or Klebsiella spp. Treated animals clinically improved significantly more compared with control cows. No significant differences were observed between treated and control animals in milk production or linear score before or after clinical mastitis. Treated animals left the study less frequently compared with control animals.

The purpose was to evaluate 2 intramammary treatments for mild-to-moderate cases of clinical mastitis in a noninferiority comparison. Noninferiority trials are intended to show whether a given treatment, hetacillin potassium, has at least comparable efficacy as the reference treatment, ceftiofur hydrochloride. Treatments can be deemed inferior to the reference treatment by an amount less than the margin of noninferiority, or inconclusive if the confidence interval crosses the margin of noninferiority. Cows with clinical mastitis from 6 farms were considered for enrollment. Using a randomized design, cows with mild or moderate mastitis in 1 quarter were assigned to on-label treatment with either ceftiofur or hetacillin. A total of 596 cows met the criteria needed for continued enrollment. Treatment distribution resulted in 309 cows in the ceftiofur group and 287 cows in the hetacillin group. Mixed regression analysis was performed for the following outcomes: bacteriological cure, pathogen cure, clinical cure, postevent milk production and linear score, and survival to d 30 and 60. Cox proportional hazards analysis was used to describe treatment effect on survival and mastitis risks. Bacteriological cure, defined as absence of causative organism in samples retrieved at d 14 and 21 postmastitis, was similar between groups. No significant statistical differences were found in cure risk, and noninferiority of hetacillin relative to ceftiofur for bacteriological cure was conclusive (hetacillin=67%, ceftiofur=72%). Absence of a pathogen on both follow-up samples designated a cow as a pathogen cure. Pathogen cure was similar between treatment groups and noninferiority of hetacillin relative to ceftiofur was shown (hetacillin=35%, ceftiofur=32%). Clinical cure (hetacillin=68%, ceftiofur=64%), postevent milk production (hetacillin=37.0kg, ceftiofur=38.2kg), and linear scores (hetacillin=3.4, ceftiofur=3.1) were also not statistically different between treatment groups. Noninferiority of hetacillin relative to ceftiofur was shown for survival to d 30 and survival to d 60, whereas hetacillin was more likely to have a clinical cure than ceftiofur by d 4. No differences were seen between groups when Cox proportional hazards were performed, neither for exit from the herd in the 60 d following the event nor in the risk for a subsequent mastitis event. These findings can be used to develop farm-specific protocols for clinical mastitis treatment.

Our objective was to compare the insemination dynamics and time to pregnancy for up to 100 d after the beginning of the artificial insemination period (AIP) for heifers managed with first artificial insemination (AI) service programs that relied primarily on insemination at detected estrus (AIE) after PGF 2α treatments, timed artificial insemination (TAI), or a combination of both. Holstein heifers were randomly assigned to receive first AI service with sex-selected semen after 368 ± 10 d of age with (1) AIE after synchronization of estrus with up to 3 PGF 2α treatments every 14 d starting on the first day of the AIP (PGF+AIE; n = 317). Heifers not AIE up to 9 d after the third PGF 2α received a 5-d Cosynch protocol with progesterone supplementation [GnRH + controlled internal drug release insert (CIDR)-5 d-CIDR removal and PGF 2α-3 d-GnRH and TAI] before TAI. Heifers detected in estrus from CIDR removal and PGF 2α until the day before TAI received AIE with no GnRH treatment; (2) 2 PGF 2α treatments 14 d apart with the second treatment at the beginning of the AIP (PGF+TAI; n = 334). Heifers received AIE for up to 9 d after the second PGF 2α treatment. Heifers not AIE received TAI after the 5-d Cosynch protocol and (3) TAI after the 5-d Cosynch protocol (ALL-TAI; n = 315). Heifers failing to conceive to a previous AI received a subsequent AI with conventional semen at detected estrus or TAI after the 5-d Cosynch protocol. Binomial outcomes were analyzed by logistic regression, whereas time to AI and pregnancy were analyzed with Cox's regression. The hazard of first AI up to 45 d of the AIP was greater for ALL-TAI than for PGF+AIE

Our objective was to evaluate cash flow for dairy heifers managed for first service with programs that relied primarily on insemination at detected estrus (AIE), timed AI (TAI), or a combination of both. Holstein heifers from 2 commercial farms were randomized to receive first service with sexed semen after the beginning of the AI period (AIP) at 12 mo of age with 1 of 3 treatments:(1) PGF+AIE (n = 317): AIE after PGF 2α injections every 14 d (up to 3) starting at the beginning of the AIP; heifers not AIE 9 d after the third PGF 2α were enrolled in the 5d-Cosynch (5dCP) protocol; (2) ALL-TAI (n = 315): TAI after ovulation synchronization with the 5dCP protocol; and (3) PGF+TAI (n = 334): AIE after 2 PGF 2α injections 14 d apart (second PGF 2α at beginning of AIP). If not AIE 9 d after the second PGF 2α , the 5dCP protocol was used for TAI. After first service heifers were AIE or received TAI after the 5dCP with conventional semen. Individual heifer cash flow (CF) for up to a 15-mo period (d 0 = beginning of AIP) was calculated using reproductive cost (rearing only), feed cost (rearing only), income over feed cost (lactation only), calf value, operating cost, and with or without replacement cost. A stochastic analysis with Monte Carlo simulation was used to estimate differences in CF for a range of market values for inputs and outputs. Time to pregnancy for up to 100 d after the beginning of the AIP was analyzed by Cox's proportional regression, binary data with logistic regression, and continuous outcomes by ANOVA. Time to pregnancy (hazard ratio and 95% CI) was reduced for the ALL-TAI versus the PGF+AIE treatment (1.20; 1.02-1.42), but it was similar for ALL-TAI and PGF+TAI (1.13; 0.95-1.33) and the PGF+AIE and PGF+TAI treatments (1.

The objective of this experiment was to compare time to pregnancy and proportion of cows not pregnant 210 d after first service for cows managed for second and subsequent artificial insemination (AI) services with a reproductive management program that promoted reinsemination at detected estrus (AIE) or a program that promoted timed AI (TAI). After first service, lactating Holstein cows were blocked by parity and randomly assigned to d 32 Resynch (D32R; n = 464) or AIE Resynch (AIER; n = 512). To determine the effect of management strategies on time to pregnancy and cows not pregnant by the end of a 210 d at-risk period after first AI service, cows remained in AIER and D32R until pregnancy or herd exit. Cows in D32R received a GnRH treatment 32 ± 3 d after AI (first treatment intervention; FTI). Nonpregnancy diagnosis was conducted 7 d later by transrectal ultrasonography when nonpregnant cows with a corpus luteum (CL) ≥15 mm completed the Resynch protocol (PGF 2α , 56 h later GnRH, and 16 to 18 h later TAI) and cows without a CL (NoCL cows) were enrolled in a PreG-Ovsynch protocol (GnRH, 7 d later GnRH, 7 d later PGF 2α , 56 h later GnRH, and 16 to 18 h TAI) to receive TAI. For the AIER treatment, nonpregnant cows with a CL ≥15 mm observed by transrectal ultrasonography 32 ± 3 d after AI (i.e., FTI) received PGF 2α to induce estrus. Cows not AIE within 7 d were enrolled in Resynch (GnRH, 7 d later PGF 2α , 56 h later GnRH, and 16 to 18 h TAI). Cows in the NoCL group in AIER were enrolled in PreG-Ovsynch. Detection of estrus was performed based on visual observation of behavioral signs of estrus and tail-paint removal. Binomial data were analyzed with logistic regression and time to event data with Cox's proportional regression. After the FTI, a greater proportion of cows were AIE in AIER than D32R (36.0 vs. 11.9%) and more cows were AIE within 7 d of the FTI for AIER (25.0%) than D32R (4.8%). Overall pregnancy per AI at 68 ± 3 d after AI did not differ (AIER = 35.5% vs. D32R = 34.7%). The hazard of pregnancy up to 210 d after first AI for all cows enrolled (hazard ratio = 1.04, 95% CI 0.90 to 1.19) and for cows that received treatments only (D32R = 308, AIER = 349; hazard ratio = 1.00, 95% CI 0.85 to 1.19) did not differ. We conclude that a program aimed at increasing the proportion of cows reinseminated at detected estrus by treatment with PGF 2α at 32 ± 3 d after AI may be an alternative strategy for dairy farms that prefer or need to inseminate more cows at detected estrus rather than by TAI.