Analysis of the risk factors relating to cows' resistance to Rhipicephalus microplus ticks during the peripartum

This study aimed to evaluate season, breed, number of lactations and milk production as risk factors relating to Rhipicephalus microplus infestation in dairy cows during the peripartum. Eighty-four animals were randomly selected through proportional stratified sampling. All engorged and partially engorged female R. microplus specimens measuring 4.5-8.0 mm were counted during the 5 weeks before calving, calving week and 5 weeks after calving. The peripartum had a significant effect [calving (p < 0.05; prevalence ratio (PR)= 3.12) and post calving (p < 0.05; PR = 2.02)] on R. microplus infestation. Although the average tick count was higher during the rainy season than during the dry season, there was no significant difference (p = 0.055; PR = 0.63). The average R. microplus count was significantly higher (p < 0.05; PR = 2.10) in Bos taurus animals, followed by F1 (p < 0.05; PR = 1.64) and Girolando (p < 0.05; PR = 1.39). The average R. microplus count was significantly higher (p < 0.05; PR = 0.97) in first-lactation animals, followed by those at the second, third and, fourth or subsequent lactation. Milk production showed a negative correlation with R. microplus count, such that high-production animals were significantly (p = 0.003; PR = 2.04) more vulnerable to infestation than were low-production animals. First-lactation and high-production B. taurus animals had greatest vulnerability to R. microplus infestation over the peripartum period, and constituted the at-risk group in the dairy herd.u

In vivo embryo production in cows superovulated 1 or 2 days after ovum pick-up

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Manipulation of the periovulatory sex steroidal milieu affects endometrial but not luteal gene expression in early diestrus Nelore cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Risk factors for anaplasmosis in dairy cows during the peripartum

Anaplasma marginale is endemic in tropical and subtropical areas around the world. Some studies have suggested that cows during peripartum may present a transient immunosuppression state and development of clinical signs of anaplasmosis. The aim of this study was to investigate the relationship between some risk factors and the seroprevalence of A. marginale in dairy cows during peripartum in Rio de Janeiro, Brazil. The risk factors analyzed in association with the prevalence of antibodies against A. marginale in dairy cows were calving season, reproductive experience, breed standard, tick infestations, stocking density, and milk yield. The antibodies against A. marginale were tested in indirect enzyme-linked immunosorbent assays. A primary screening using a 2 x k contingency table of the exposed variables with the outcomes was performed. All variables for which p < 0.20 were included in a fixed effects log regression. The risk factors investigated to anaplasmosis were calving (OR 2.61, IC 1.08-7.63), breed standard (OR 3.83, IC 0.08-0.28), reproductive experience (OR 33.7, IC 2.14-5.16), milk yield (OR 3.9, IC 2.24-7.03), Rhipicephalus microplus infestations (OR 10.3, IC 0.05-0.17), and stocking density (OR 22.3, IC 0.05-0.17). Low titers of antibodies against A. marginale during peripartum had been characterized as a period previous to development of clinical anaplasmosis. Thus, studies on anaplasmosis should consider each farm as an epidemiological unit, where environmental and immunological factors may influence the endemic status of the pathogen.

Comportamento ingestivo de vacas leiteiras alimentadas com silagem de milheto ou milho

The objective of this study was to evaluate the ingestive behavior of dairy cows fed corn and millet silage with a 5 mm particle size without inoculant, millet silage with a 5 mm particle size with inoculant, millet silage with a 20 mm particle size without inoculant, millet silage with a 20 mm particle size with inoculant. Five cows Holstein x Gir, with approximately 100 days of lactation at the beginning of the experiment and a mean body weight of 550 kg, producing an average of 15 kg of milk per day were used. The animals were arranged in a randomized 5 x 5 Latin square. The total feeding time, rumination time, chewing time, number of alimentary bolus, rumination time for bolus and number of chews was determined. The variables that make up the feeding behavior were not affected when the cows were fed different millet silages compared with corn silage. Cows fed corn silage and millet silage of 5 mm particle size had a higher intake of dry matter and neutral detergent fiber. A particle size between 5 and 20 mm, the presence or absence of inoculum and the type of silage with DM at 28%, does not affect the total feeding time, ruminating and resting of cows with an average production of 15.2 kg per day. The presence of the inoculant does not affect the intake of dry matter and neutral detergent fiber. Cows fed diets containing corn silage or pearl millet silage with a 5 mm particle size fed more DM.

Relationships between growth of the preovulatory follicle and gestation success in lactating dairy cows

This report summarizes three studies conducted with lactating dairy cows aiming to increase pregnancy rates to fixed time artificial insemination (TAI) protocols. Experiment 1 was designed to determine if changing the timing of PGF2 alpha treatment during an E2/P4-based program would affect fertility to TAI or fixed-time embryo transfer (TET). In experiment 2, pregnancy rates to AI were compared following synchronized ovulation using two protocols that have been developed to reduce the period between follicular wave emergence and TAI. The Ovsynch-type protocol utilizes GnRH to synchronize the follicular wave by inducing ovulation of a dominant follicle at the beginning of the protocol, and to synchronize ovulation at the end of the protocol allowing TAI. In contrast, E2/P4-based protocols utilize E2 products in the presence of P4 to induce atresia of antral follicles and synchronize emergence of a new follicular wave. At the end of E2/P4-based protocol another E2 treatment in the absence of P4 is used to induce LH release and synchronize ovulation and allow TAI. Experiment 3 was designed to determine whether increasing the length time interval with reduced circulating P4 (proestrus) would increase fertility in a TAI program that utilized E2 and P4 to synchronize ovulation of cycling, lactating dairy cows. The overall conclusions are that circulating concentrations of progesterone and estradiol prior to and circulating concentrations of progesterone following ovulation can affect fertility in cattle. In addition, small increases in P4 concentrations near the time of AI, due to lack of complete CL regression, result in reductions in fertility. Earlier treatment with PGF2 alpha should allow greater time for CL regression, an increase in estradiol and subsequent reductions in circulating P4 that could be critical for fertility. Optimization of follicle size in TAI programs is clearly an intricate balance between oocyte quality, adequate circulating E2 near AI, and adequate circulating P4 after AI.

The effect of follicle age on pregnancy rate in beef cows

The effect of the age of the ovulatory follicle on fertility in beef cows was investigated. Multiparous (n = 171) and primiparous (n = 129) postpartum beef cows in 2 groups (G1 and G2) received estradiol benzoate (EB; 1 mg/500 kg BW, intramuscular [i.m.]) 5.5 d (G1; n = 162) and 6.5 d (G2; n = 138) after the final GnRH of a synchronization program (5d CO-Synch + CIDR) to induce emergence of a new follicular wave (NFW), followed by prostaglandin F2 alpha (PGF2 alpha; 25 mg, i.m.) administration either 5.5 d (young follicle, YF; n = 155) or 9.5 d (mature follicle, MF; n = 145) after EB. Estrous detection coupled with AI 12 h later (estrus-AI) was performed for 60 h (MF) and 84 h (YF) after PGF(2 alpha); cows not detected in estrus within this period received timed AI (TAI) coupled with GnRH at 72 and 96 h, respectively. Within the first 72 h after PGF(2 alpha), more (P < 0.01) cows in the MF (76.3%) than YF treatment (47.7%) exhibited estrus, but through 96 h, the proportion detected in estrus (P < 0.05) and interval from PGF(2 alpha) to estrus (P < 0.01) were greater in the YF than MF treatment (88.6% vs. 76.3%, 78.9 +/- 0.8 vs. 57.5 +/- 1.6 h, respectively). Age of the ovulatory follicle at AI was greater (P < 0.01) in the MF (9.32 +/- 0.04 d) than YF (6.26 +/- 0.02 d) treatment, but follicle diameter at AI and pregnancy rates did not differ between MF (13.1 +/- 0.2 mm; 72.0%) and YF (12.9 +/- 0.1 mm; 67.1%) treatments. Regardless of treatment, the diameter of the ovulatory follicle at AI and pregnancy rate were greater (P < 0.01) with estrus-AI (13.1 +/- 0.1 mm; 75.0%) than TAI (12.6 +/- 0.2 mm; 55.4%). Cows in the MF treatment that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 47) were induced to ovulate with GnRH and TAI at 72h, when ovulatory follicles were 4 d old and 10.2 +/- 0.2 mm in diameter. Pregnancy rate for TAI (51.1%) in MF2 did not differ from TAI pregnancy rate (55.4%) across the MF and YF treatments. In summary, the age of the ovulatory follicle affected interval to estrus and AI but did not influence pregnancy rate in suckled beef cows.

Morphometric and Functional Characteristics of Buffaloes and Cows Corpus Luteum at Different Stages of the Estrous Cycle

The aims of the present study were to evaluate the morphometry of corpus luteum (CL) and progesterone (P-4) plasma concentration of 86 buffaloes (33 pregnant and 53 non-pregnant) and 95 cows (36 pregnant and 59 non-pregnant) at the moment of slaughter. Seventy CLs of buffaloes and 110 CL of cattle were analyzed. The CL classified as II and III were more common in both species (35.7 and 41.4% for buffaloes and 43.6 and 35.5% for cows). The 29 non-pregnant buffaloes had a total of 36 CL, being 19.4% CLI; 33.3% CL II; 27.8% CL III and 19.4% CL IV. The 51 nonpregnant cows had a total of 71 CL, being 26.8% CL I; 47.9% CL II; 21.1% CL III and 4.2% CL IV. The average diameters of bubaline and bovine CL were 5.2 +/- 0.9 and 6.4 +/- 1.8 mm (CL I); 17.6 +/- 2.6 and 19.8 +/- 3.2 mm (CL II); 17.2 +/- 2.1 and 20.0 +/- 3.2 mm (CL III); 7.8 +/- 1.8 and 8.7 +/- 2.7 mm (CL IV), respectively. The mean plasma concentrations of P4 were 5.6 (CL I); 5.4 (CL II); 4.7 (CL III) and 0.5 (CL IV) ng/mL for buffaloes and 0.02 (CL I); 6.3 (CL II) and 6.4 (CL III) ng/mL for cows. In both species, P4 concentration was similar between stages II and III. The results indicated that the characterization of the CL provides important information about the status of estrous cycle.

The influence of insemination dose on pregnancy per fixed-time artificial insemination in beef cows is affected by semen extender

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of methicillin-resistant coagulase-negative staphylococci in milk from cows with mastitis in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Diversity of Staphylococcus species and prevalence of enterotoxin genes isolated from milk of healthy cows and cows with subclinical mastitis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identification of Candida species isolated from cows suffering mastitis in four Brazilian states

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)