The aim of this study was to evaluate the mineral concentrations in the hoof horny capsule of healthy Holstein cows and cows with hoof problems associated with laminitis. Twenty-one multiparous Holstein cows with an average production of 24 L of milk/day, reared with semi-extensive nutritional management, were studied. The animals were evaluated and divided into two groups based on their locomotion score (LS, range: 0 to 4). LS greater than 2 indicated laminitis-associated lesions (lame cow group: LC), and LS = 0 indicated cows without laminitis (CWL). A sample of 30 mm 2 was collected from the hoof horny capsule at the abaxial wall to evaluate the concentrations of calcium, phosphorus, zinc, and magnesium. Calcium blood concentration was also evaluated. The LC group had lower magnesium concentration (P=0.008) and showed a trend (P=0.06) for lower calcium concentration compared to healthy animals (CWL), even though all animals were normocalcemic. The concentration of other minerals did not differ between the LC and CWL group. In conclusion, the magnesium concentration in the hoof horny capsule was lower in cows with lesions associated with laminitis, while phosphorus and zinc concentrations were not affected. The relationship between hoof lesions and calcium concentration requires further investigation.

Background: Reproductive efficiency is one of the most important factors affecting the performance dairy cattle, and fixedtime artificial insemination (TAI) is an important biotechnology factor employed in bovine livestock. The achievement of satisfactory results in TAI protocols depends of several factors, such as health and body condition, milk yield, environmental temperatures, ovulation time, semen manipulation, as well as semen quality. The goal of this study was to evaluate the conception rate of heifers and multiparous cows based on different Holstein bulls used for artificial insemination (AI). The effects of the type of management AI, animal category, and season of the year were also examined.Materials, Methods & Results: A three-year database on the reproductive management of a dairy farm was formed. All the cows and heifers were of the Holstein breed, in semi-intensive nutritional management, milked twice a day, and received a total mix ration. After 45 days in milk, when cows were observed twice daily with estrus signs, posterior artificial insemination occurred 12 h after estrus visualization was made. However, cows that were not observed in estrus were submitted to a timed artificial insemination (TAI). In this study, these fixed factors were considered: bulls utilized for the AI (totalizing 10 animals with at least 100 inseminations in each season, denoted by the letter B and a number - B1, B2, B3, B4, B5, B6, B7, B8, B9, B10); the season of the insemination (spring/summer being from November to April and autumn/winter from May to October), category animal (heifers, animals that never have been calved, or multiparous, animals that have already given birth more than once), and the type of AI (which included TAI using a protocol for synchronization, but cows having not necessarily shown estrus signs at the AI; ETAI: using protocol of synchronization, cows showing estrus signs at the AI; and AI with estrus visualization, without protocol of synchronization when animals were observed in estrus and were inseminated 12 h later. The fertility parameter of the bulls and reproductive performance in AI was based on conception rate. There was a statistical difference among different bulls in the same season (P ≤ 0.05). There was also a difference in reproductive performance of the same bulls between seasons, autumn/winter and spring/summer; B8 37.8% vs. 32.0% (P = 0.05) and B10 35.1% vs. 20.7% (P = 0.003). Regarding the individual animal category, only one bull (B6) demonstrated higher reproductive performance when utilized in the AI of heifers than multiparous 39.2% vs. 27.2% (P = 0.01). Similarly, regarding the effect of the type of AI, only one bull (B8) exhibited different results, obtaining better results for conception rate when utilized in fixed TAI with estrus visualization (35.5%) and in the AI with estrus visualization (39.0%) compared with that of TAI (19.9%) (P < 0.05).Discussion: From these results, it was observed that some bulls exhibited better performance in situations of greater challenge. In addition, some animals presented variation in efficiency with the demonstration of estrus or not. Therefore, bulls that present semen with higher fertility in certain types of AI could be utilized on a larger scale for to increase the reproductive rates in artificial insemination. The results of this study indicate that despite the tests indicating the semen that is submitted is adequate, there are still variations in quality and the reproductive efficiency of each bull. With the effects varying based on fertility and on different environmental and management situations.

Ao elaborar um manejo alimentar para vacas em lactação é necessário analisar o nível de produção, o estágio da lactação, o consumo esperado de matéria seca, o estado corporal do animal, entre outros aspectos, com a finalidade de atender as exigências nutricionais da mesma. A partir disso, é possível formular dietas para o rebanho leiteiro que irão combinar adequadamente os nutrientes de maneira a atender a demanda requerida, e estimular o potencial de produção dos animais de modo eficiente para o sistema. Entretanto, o balanceamento correto é apenas um dos componentes para um bom manejo nutricional, sendo que a mensuração de sobras é um fator importante, já que o excesso de alimento no cocho gera perdas financeiras. Com isso, o presente estudo tem como objetivo abordar as exigências nutricionais das vacas leiteiras, assim como cálculos de dieta e mensuração de sobras, pontos importantes para aumentar a lucratividade do produtor em seu sistema.

Background: Low reproductive efficiency has been one of the main factors that lead to dairy herd culling in the reproductive age. In multiparous animals, such inefficiency and culling can occur because of various factors and may be associated with occasional endocrine failures. To avoid revenue losses that incur due to lack of lactation, lactation is artificially induced in the animals that are not pregnant, using a defined protocol. The aim of this study was, therefore, to evaluate and compare the reproductive performance of heifers submitted to the induction protocol with that of pregnant heifers during the transition period. Materials, Methods & Results:Sixty Holstein heifers, 32 ± 0.6 months of age, were divided into two groups: Control Group (Control, n = 30) comprising pregnant heifers that were accompanied since 21 days before the expected calving date until 224 days in milk (DIM) and an Induction Group (Induction, n = 30) comprising non-pregnant heifers submitted to a lactation induction protocol, accompanied from the beginning of the protocol until 224 DIM. For evaluation of the endocrine profile (progesterone and estradiol concentrations) of these animals, blood samples were collected at two periods: the pre-lactation (weeks -3, -2 and -1) and post-lactation (weeks 1 and 4). Heifers from both groups were submitted to weekly reproductive evaluations, from the beginning of lactation until 35 DIM. Uterine examinations were performed using ultrasonography and vaginoscopy to evaluate uterine content, cervical opening, and mucosal aspect. Females in good reproductive health were subjected to a hormonal protocol for timed artificial insemination (TAI). The pregnancy rate of heifers that could reproduce (Control, n = 13, and Induction, n = 20) were evaluated and inseminated until 49 DIM. Progesterone levels were similar (P > 0.05) in the two groups at both pre-and post-start of lactation. Estradiol concentrations were different (P < 0.01) among groups only in the pre-lactation period. Higher levels of progesterone (P = 0.06) were observed in the induced heifers (Induction Group = 1.07 ± 0.23 ng/mL and Control Group = 0.38 ± 0.28 ng/mL). Therefore, in the fourth week, induced heifers exhibited higher luteinic activity, the progesterone concentration was above 1 ng/mL in 42% of the animals, while just 12.5% of the Control heifers had it. The overall pregnancy rate was 47.75%. The pregnancy rate recorded for induced heifers and Control heifers was 40% and 55.55%, respectively. Discussion: Progesterone and estradiol evaluations were performed in the first week after the beginning of the lactation to evaluate the metabolism and physiological concentration of the hormones used during the protocol. The measurements were again performed in the fourth week to evaluate the return to cyclicity of the heifers in both groups. The high serum concentrations of estradiol attained during the induction, in the pre-lactation period, may have possible interfered with the uterine environment and follicular population of these anima...

The aim of this study was to evaluate the economic viability of the use of a lactation induction protocol in Holstein heifers. Were collected data of nutritional, reproductive and sanitary management pre and post-lactation period from 30 induction heifers (IG) and 30 pregnant heifers (CG). All animals were inseminated around 14 months of age and started lactation at 23±4 months. The animals of IG were heifers do not pregnant after two inseminations and natural service e were induced to lactation according to protocol: from the 1st to the 8th day, 30 mg of estradiol benzoate were administered daily, together with 300 mg of progesterone. From the 9th until the 14th, animals only received daily doses of 20 mg estradiol benzoate. On 16th day, 0.56 mg of sodium cloprostenol was administered and injections of 40 mg of dexamethasone sodium phosphate were administered daily from the 19th to the 21st day. On the 1st, 8th, 15th and 22nd day, the animals received a dose of sometribove zinc. The animals of CG were managed according to the farm routine. The costs of the CG during pre and post lactation (nutrition, sanitary, reproduction management) e were higher than the IG, however, when evaluating the economic viability due to lower milk production, the induced group did not leave profit in the first year of use. When comparing the lactation induction with the sale of animals that did not conceive and purchase of animals for replacement, this last scenario showed itself as a better alternative.