Influence of the suckling management on the estrus return in ewes at post-partum

Conduziu-se este estudo, com o objetivo de avaliar o retorno ao estro pós-parto de ovelhas submetidas a diferentes manejos de mamada. Foram utilizados 56 ovelhas Santa Inês e Bergamácia, 71 cordeiros e 3 rufiões. Os manejos de mamada (MM) foram: 1: contínua; 2: duas mamadas diárias; 3: mamada durante a noite. O período experimental foi dos 15 dias pós-parto até o desmame aos 60 dias. Até os 15, dias de idade os cordeiros permaneceram com suas mães em período integral. No MM 1, as ovelhas permaneceram com seus cordeiros em uma baia, em período integral. No MM 2, as ovelhas passaram a noite em uma baia e o dia em pastagem, momento em que não possuíam contato físico e visual com as crias. Seus cordeiros permaneceram em outra baia em período integral, para onde as ovelhas eram encaminhadas no momento da amamentação. No MM 3, as ovelhas passaram o dia em pastagem e a noite com seus cordeiros em uma baia, na qual os cordeiros permaneceram em período integral. Todas as ovelhas e todos os cordeiros receberam alimentação nas baias. Para identificação das ovelhas em estro foram utilizados rufiões, os quais permaneceram com elas em período integral. Os dados foram submetidos à análise de variância (PROC GLM, Sas®), e as médias comparadas por contrastes. O MM 2 possibilitou retorno ao estro pós-parto precoce quando comparado ao MM 3 e ao MM 1. Houve pouca ou nenhuma influência do anestro lactacional, pois 80% das ovelhas apresentaram estro durante a amamentação.The objective of this work was to evaluate the return to postpartum estrus of ewes submitted to different suckling managements. Fifty-six (56) Santa Ines and Bergamácia ewes, 71 lambs and 3 teasers were utilized. The suckling managements (MM) were: 1: Continuous; 2: Two daily sucklings; 3: suckling during the night. The experimental period was from 15 days postpartum to weaning at 60 days. The lambs stayed with their mothers until they were 15 days old. For MM 1, the ewes remained with their lambs in a pen for the duration of the study. For MM 2, the ewes spent the night in a pen and the day in pasture; they had no visual or physical contact with their sucklings during the day. Their lambs were kept in a separate pen during the day, where the ewes were led at suckling time. For MM 3, the ewes spent the day in pasture and the night with their lambs in a pen, in which the lambs remained the whole time. All the ewes and all the lambs were fed in the pens. For identification of the ewes in estrus, teasers were utilized, which remained with them the whole time. The data was submitted to an analysis of variance (PROC GLM, Sas®) and the means compared by contrasts. MM 2 made it possible for ewes to return to postpartum estrus early when compared with MM 3 and MM 1. There was little or no influence of lactation anestrous, since 80% of the ewes presented estrus during suckling

Progesterone production in superovulated holstein heifers and in crossbred recipient of embryo supplemented with betacarotene and tocopherol Produção de progesterona em novilhas Holandesas superovuladas e receptoras de embrião mestiças suplementadas com betacaroteno e tocoferol

Two experiments were conducted to evaluate the effect of the intramuscular injection of betacarotene associated to tocopherol on the plasma concentration progesterone of superovulated Holstein heifers (experiment 1) and in crossbred (Bos taurus x Bos indicus) heifers submitted to fixed-time embryo transfer (FTET, experiment 2). In experiment 1, after estrus synchronization and superovulation animals were inseminated 12 and 24 hours after estrus onset and embryos flushed 7 days later. Heifers were allocated randomly to one of three treatments: Control; T800 (800 mg of betacarotene plus 500 mg of tocopherol) and T1200 (1,200 mg of betacarotene plus 750 mg of tocopherol). The treatments were given on the day of ear implant placement and repeated on the first day of superovulation. Blood samples were collected on D0, D5, D9, D12 and D16. In experiment 2, treatments were imposed at intravaginal device insertion (D0). The same experimental design, as in experiment 1, was used. Blood samples were collected on D17 (embryos implanted) for progesterone determination by radioimmunoassay. In experiment 1, average plasma progesterone concentrations after corpora lutea formation (D12 plus D16 means) were 13.7±1.8 ng/ml, 14.5±2.3 ng/ml and 10.8±2.3 ng/ml for control, T800 and T1200, respectively, and did not differ (P=0.44). In experiment 2, progesterone concentrations on D17 in Control (8.88±0.57 ng/ml), T800 (7.48±0.64 ng/ml) and T1200 (5.90±1.33 ng/ml) groups were similar (P=0.11). Results indicate that the supplemental betacarotene and tocopherol injections did not influence peripheral progesterone concentrations in superovulated Holstein donors and crossbreed recipients heifers.<br>Dois experimentos foram conduzidos para avaliar o efeito da injeção intramuscular de betacaroteno associada ao tocoferol, na concentração plasmática de progesterona de novilhas Holandesas superovuladas (Experimento 1) e em novilhas cruzadas (Bos taurus x Bos indicus) submetidas à transferência embrionária em tempo fixo (TETF, experimento 2). No experimento 1, após a sincronização do estro e superovulação, os animais foram inseminados entre 12 a 24 h após o início do estro e os embriões recuperados após 7 dias. As novilhas foram divididas, aleatoriamente, em 1 de 3 tratamentos: Controle (duas injeções de soro); T800 (800 mg de betacaroteno mais 500 mg de tocoferol) e T1200 (1.200 mg de betacaroteno mais 750 mg de tocoferol). Os tratamentos foram administrados no dia da colocação do implante de progesterona e repetido no primeiro dia da superovulação. As colheitas de sangue foram realizadas no D0, D5, D9, D12 e D16. No experimento 2, os tratamentos foram realizados no momento da inserção do dispositivo de progesterona (D0). Utilizou-se o mesmo delineamento do experimento 1. A colheita de sangue para a determinação da progesterona por radioimunoensaio foi realizada no D17 (inovulação embrionária). No experimento 1, a concentração plasmática média, após formação do corpo lúteo (média da soma de D12 com D16) foi de 13,7±1,8 ng/ml, 14,5±2,3 ng/ml e 10,8±2,3 ng/ml para os grupos Controle, T800 e T1200, respectivamente, e não diferiram (P=0,44) entre os tratamentos. No experimento 2, a concentração de progesterona nas receptoras, no dia 17, foi semelhante (P=0,11) entre os grupos controle (8,88±0,57 ng/ml), T800 (7,48±0,64 ng/ml) e T1200 (5,90±1,33 ng/ml). Os resultados indicaram que as injeções de suplemento com betacaroteno e tocoferol não influenciaram na concentração plasmática de progesterona em novilhas Holandesas doadoras de embriões e em novilhas cruzadas, receptoras de embrião

FACTORS AFFECTING PREGNANCY RATES AFTER OVUM PICK UP-DERIVED EMBRYO TRANSFER IN LACTATING HOLSTEIN RECIPIENTS UNDER TROPICAL CONDITIONS

ABSTRACTHigh milk production, heat, physiological status and management impair reproduction in Holstein cows. The use of in vivo-produced embryos has been reported as an alternative to enhance pregnancy outcome in the tropics; however there are several limitations for its production, especially from variations in superovulatory responses. The in vitro production of embryos would avoid such variations, but few studies have been reported. This study aims to verify the effects of variables related to recipients under a program of routine in vitro embryo transfer on a commercial dairy farm in southeastern Brazil. It was hypothesized that pregnancy rates after transfer of ovum pick up or OPUderived embryos (ET) to lactating Holstein recipients may be influenced by recipient GnRH-treatment at ET, parity, milk production and body condition score. Recipients (267) were allocated to one of three i.m. treatments given at ET: Control (92) - 2.5 ml saline; Buserelin (86) - 10 μg Buserelin acetate; Deslorelin (89) - 750 μg Deslorelin acetate. Ultrasound images and blood samples were taken at ET and seven days later. The first pregnancy diagnosis was performed between 30-40 days and the second between 60-80 days post ET. Data were analyzed by GENMOD (SAS(r)). The proportion of pregnant cows was greater (P&lt;0.05) in Buserelin-treated recipients (38.3%) at the first pregnancy diagnosis than Controls (24.1%), but similar to Deslorelin and control cows at the second diagnosis (13.0, 20.9 and 14.6% in Control, Buserelin and Deslorelin, respectively). In conclusion, Buserelin improved pregnancy rate only transitorily, under the present conditions

Estimation methods and correction factors for body weight in Mangalarga Marchador horses

ABSTRACT The objective was to evaluate the accuracy of six body weight (BW) estimating methods in Mangalarga Marchador horses (MM) (n = 318): method A - tape placements at three different positions around the thoracic girth; B - Crevat and Quetelec's formula; C - Hall's formula; D - Hintz and Griffiths’ table; E - Santos’ table; and F - Cintra's formula. For additional analyses, gender, age, and gestational stage were considered. Estimated average BW was compared to the actual scale weight by the paired T test, mean predicted error, and determination coefficient. In the general population, methods A (position 3), B, and C estimated BW that were different from that of the scale. Method A, at positions 1 and 2, was more accurate in predicting the scale weight results compared with all other methods. For pregnant mares, the tape in positions 1 and 2 in method A did not differ from those of the scale. Method A in positions 1 and 2 and the table (method E) may be used to estimate the BW of males and females of different ages and/or gestational stages. To use Methods B and C, correction factors are necessary to precisely estimate the body weights in this breed

Use of sex-sorted and unsorted frozen/thawed sperm and in vitro fertilization events in bovine oocytes derived from ultrasound-guided aspiration

The objective was to investigate the effects of sex-sorting on early fertilization events in ovum pick up (OPU) derived oocytes fertilized in vitro with frozen-thawed sperm at different co-incubation lengths. Eighty-four OPU sessions were carried out in 18 cyclic, dry and non-stimulated Holstein Friesian and German black pied cows. Ovum pick up oocytes were matured in vitro for 24 hours and fertilized with frozen-thawed sex sorted or unsorted sperm from the same ejaculate. Fertilization was achieved by two experimental protocols: 1) short gamete co-incubation length: 4, 8 and 12 hours; and 2) long gamete co-incubation length: 18 and 24 hours. After in vitro fertilization, ova were fixed and stained to identify early fertilization events. Sperm penetration, monospermy, pronuclear formation and syngamy did not differ, whether sexed or unsexed sperm was used. Overall, the findings demonstrate similar fertilizing potential between sex-sorted and unsorted sperm