Genetic correlations between categorical morphological traits in Nelore cattle by applying Bayesian analysis under a threshold animal model

P>In this study, Bayesian analysis under a threshold animal model was used to estimate genetic correlations between morphological traits (body structure, finishing precocity and muscling) in Nelore cattle evaluated at weaning and yearling. Visual scores obtained from 7651 Nelore cattle at weaning and from 4155 animals at yearling, belonging to the Brazilian Nelore Program, were used. Genetic parameters for the morphological traits were estimated by two-trait Bayesian analysis under a threshold animal model. The genetic correlations between the morphological traits evaluated at two ages of the animal (weaning and yearling) were positive and high for body structure (0.91), finishing precocity (0.96) and muscling (0.94). These results indicate that the traits are mainly determined by the same set of genes of additive action and that direct selection at weaning will also result in genetic progress for the same traits at yearling. Thus, selection of the best genotypes during only one phase of life of the animal is suggested. However, genetic differences between morphological traits were better detected during the growth phase to yearling. Direct selection for body structure, finishing precocity and muscling at only one age, preferentially at yearling, is recommended as genetic differences between traits can be detected at this age.

13,14-Dihydro-15-Keto Prostaglandin F-2 alpha Release in Response to Oxytocin Challenge Early Post-Partum in Anoestrous Nelore Cows Submitted to Temporary Calf Removal and Progesterone Priming

The study evaluated, in early post-partum anoestrous Nelore cows, if the increase in plasma oestradiol (E2) concentrations in the pre-ovulatory period and/or progesterone priming (P4 priming) preceding ovulation, induced by hormonal treatment, reduces the endogenous release of prostaglandin PGF(2)alpha and prevents premature lysis of the corpus luteum (CL). Nelore cows were subjected to temporary calf removal for 48 h and divided into two groups: GPE/eCG group (n = 10) and GPG/eCG group (n = 10). Animals of the GPE/eCG group were treated with a GnRH agonist. Seven days later, they received 400 ID of eCG, immediately after PGF(2)alpha treatment, and on day 0, 1.0 mg of oestradiol benzoate (EB). Cows of the GPG/eCG group were similarly treated as those of the GPE/eCG group, except that EB was replaced with a second dose of GnRH. All animals were challenged with oxytocin (OT) 9, 12, 15 and 18 days after EB or GnRH administration and blood samples were collected before and 30 min after OT. Irrespective of the treatments, a decline in P4 concentration on day 18 was observed for cows without P4 priming. However, animals exposed to P4 priming, treated with EB maintained high P4 concentrations (8.8 +/- 1.2 ng/ml), whereas there was a decline in P4 on day 18 (2.1 +/- 1.0 ng/ml) for cows that received GnRH to induce ovulation (p < 0.01). Production of 13,14-dihydro-15-keto prostaglandin F-2 alpha (PGFM) in response to OT increased between days 9 and 18 (p < 0.01), and this increase tended to be more evident in animals not exposed to P4 priming (p < 0.06). In conclusion, the increase in E2 during the pre-ovulatory period was not effective in inhibiting PGFM release, which was lower in P4-primed than in non-primed animals. Treatment with EB promoted the maintenance of elevated P4 concentrations 18 days after ovulation in P4-primed animals, indicating a possible beneficial effect of hormone protocols containing EB in animals with P4 priming.

Effects of flunixin meglumine, recombinant bovine somatotropin and/or human chorionic gonadotropin on pregnancy rates in Nelore cows

The objective was to compare pharmacological strategies aiming to inhibit prostaglandin F2 alpha (PGF(2 alpha)) synthesis (flunixin meglumine; FM), stimulate growth of the conceptus (recombinant bovine somatotropin; bST) and progesterone (P(4)) synthesis (human chorionic gonadotropin; hCG), as well as their combinations, regarding their ability to improve pregnancy rates in beef cattle. Lactating Nelore cows (N = 975), 35 to 70 days postpartum, were synchronized and inseminated by timed artificial insemination (TAT) on Day 0. on Day 7, cattle were allocated into eight groups and received one of the following treatments: saline (S) on Days 7 and 16 (Group Control); S on Day 7 and FM on Day 16 (Group FM); bST on Day 7 and S on Day 16 (Group bST); bST on Day 7 and FM on Day 16 (Group bST + FM); hCG on Day 7 and S on Day 16 (Group hCG); hCG on Day 7 and FM on Day 16 (Group hCG + FM); bST and hCG on Day 7 and S on Day 16 (Group bST + hCG), or bST and hCG on Day 7 and FM on Day 16 (Group bST + hCG + FM). The aforementioned treatments were administered at the following doses: 2.2 mg/kg FM (Banamine (R); Intervet Schering-Plough, Cotia, SP, Brazil), 500 mg bST (Boostin (R); Intervet Schering-Plough), and 2500 IU hCG (Chorulon (R); Intervet Schering-Plough). Pregnancy diagnosis was performed 40 days after TAI by transrectal ultrasonography. Pregnancy rates were not significantly different among treatments. However, there was a main effect of hCG treatment to increase pregnancy rates (63.0 vs. 55.4%; P = 0.001). Concentrations of P(4) did not differ significantly among groups on Day 7 or on Day 16. However, consistent with the higher pregnancy rates, hCG increased P(4) concentrations on Day 16 (10.6 vs. 9.6 ng/mL, respectively; P = 0.05). We concluded that hCG treatment 7 days after TAI improved pregnancy rates of lactating Nelore cows, possibly via a mechanism leading to induction of higher P(4) concentrations, or by reducing the luteolytic stimulus during maternal recognition of pregnancy. (C) 2011 Elsevier B.V. All rights reserved.

Aspectos da reprodução e alimentação de Neoplecostomus microps (Loricariidae, Neoplecostominae) na microbacia do Ribeirão Grande, serra da Mantiqueira oriental (Estado de São Paulo)

Reproduction and feeding aspects of Neoplecostomus microps (Loricariidae, Neoplecostominae) in the Ribeirao Grande system, eastern Serra da Mantiqueira (São Paulo State). The Ribeirao Grande system is located in the slope of the Serra da Mantiqueira and is surrounded by Atlantic forest. Eight sites were surveyed in the Ribeirao Grande system, during the winter (July 2001), spring (October 2001), summer (February 2002) and fall (April 2002). Samples were made with an electrofishing device. Gonad maturation, levels of stomach fullness and fat content were analyzed and their distributions reported in an annual cycle. Neoplecostomus microps has a spawning in the spring through to summer. The size at sexual maturity is about 5.9 cm total length for males and 6.9 cm for females. The high values in October and February by the gonadosomatic index and the relative condition factor coincided with the spawning period. In the diet of N. microps were found Diptera larvae (Simulium, Chironomus), Plecoptera nymphs and Coleoptera aquatic Larvae (Psephenus). The increased feeding from summer to fall provided fat accumulation. During subsequent seasons, fish may utilize visceral fat reserves for maintenance and reproduction. The reproductive pattern and feeding are interpreted as being an adaptation with respect to temporal and spatial variation and food availability.

Reprodução de Meloidogyne incognita, M. javanica e Pratylenchus coffeae em Diferentes Cultivares de Bananeira

Banana (Musa spp.) is one of the most consumed fruits in the world, and it is cultivated in many tropical countries. In Brazil, the productivity is low due to several factors such as the incidence of pests and diseases. The nematodes are among the most important problems found in the production of bananas. This research studied the reproduction of Meloidogyne incognita race 2, M. javanica and Pratylenchus coffeae in different cultivars of banana. The evaluation of the experiments with Meloidogyne spp. was carried out 120 days after the inoculation. The analyzed parameters were: number of gall, number of the external masses of eggs, number of eggs per gram of root, reproduction factor and number of juveniles in the soil. The evaluation of the experiment with P. coffeae was carried out 90 days after the inoculation; the final population was evaluated. The cultivars PV-0344, Maca, Grande Naine, FHIA 01, Thap Maeo and Prata Ana allowed greater multiplication of P. coffeae than Caipira, SH-3640 and FHIA-18. For M. javanica, the cultivars Calypso, Bucanneer, Grande Naine, PV-0344, Nanicao Magario, FHIA-02, SH-3640, Pacovan, and Prata Ana exhibited larger populations, decreasing in Maca. All cultivars allowed high multiplication rates of M. incognita.