João José Assumpção de Abreu Demarchi

Efeito da inclusão de polpa cítrica peletizada na confecção de silagem de capim-elefante (Pennisetum purpureum, Schum.)

The objectives of this trial were to evaluate the effects of regrowth age of elephantgrass (Pennisetum purpureum Schum. cv. Napier), and citrus pulp addition on the fermentation pattern and aerobic stability of their silage. In addition to that, this research also aimed to create a recommendation index of citrus pulp addition taking into account the moisture concentration of the grass, in order to decrease costs of technology adoption. Laboratory silos (6 L-capacity each) were used and 20 treatments were tested, corresponding to 5 different grass regrowth ages (40, 60, 80, 100, or 120 days after harvesting) and four levels of citrus pulp pellets (0, 3, 6, or 9%, based on grass fresh matter) in a factorial arrangement 5 x 4, with four replicates. Regrowth age and citrus pulp addition level interacted for acetic, propionic, butyric, and lactic acid concentrations, lactic/acetic acid ratio, pH, ammoniacal nitrogen, and maximum temperature, but did not for alcohol concentration, in vitro DM digestibility, time to achieve the maximum temperature, rate for increasing temperature, and time for increasing temperature in 2oC. In general, the addition of citrus pulp improved fermentation pattern of silages, with greater effect when silages were produced with high moisture grasses. Based on acetic acid concentration and using derivations from the surface equation, it was possible to recommend the addition of 0.7% of citrus pulp (based on grass fresh matter) for each percentage unit of grass DM lower than 32%. Therefore, the optimum addition level of citrus pulp which optimizes silage quality is equal to (32 - DM) x 0.7.

Combined use of ionophore and virginiamycin for finishing Nellore steers fed high concentrate diets

Zebu cattle fed high concentrate diets may present inconsistent performance due to the occurrence of metabolic disorders, like acidosis. The isolated use of ionophores and virginiamycin in high grain diets can improve animal performance and reduce the incidence of such disorders, but recent studies suggested that their combination may have an additive effect. Thus, 72 Nellore steers, 389 ± 15 kg initial body weight (BW), were confined and fed for 79 days to evaluate the combination of virginiamycin and salinomycin on performance and carcass traits. Animals were allocated to a randomized complete block design by BW, in a 2 × 2 factorial arrangement of treatments, with two concentrate levels (73 and 91 %) and two virginiamycin levels (0 and 15 mg kg-1), and salinomycin (13 mg kg-1) included in all diets. The interaction was not significant (p > 0.05). Dry matter intake (DMI), average daily gain (ADG), gain-to-feed ratio (G:F), starch consumed, and fecal starch content were higher (p 0.05) between treatments. Starch consumed and estimated dietary net energy for maintenance (NEm) and gain (NEg) were higher (p < 0.05) for virginiamycin-treated animals, with no substantial effects on carcass traits. The inclusion of virginiamycin in finishing diets containing salinomycin reduced DMI while maintaining ADG and improving NEm and NEg, suggesting an additive effect of virginiamycin and ionophores, but without affecting carcass quality.

Erradicação do herpesvírus bovino - 1 (BHV-1) de um rebanho bovino leiteiro em manejo semi-intensivo

To eradicate the BHV-1 from a dairy cattle herd without vaccination, a preliminary serological survey was performed in 154 animals, that revealed 15.6% seropositives for BHV-1. The test used was serum neutralization with the microtitration technique. The seropositive nonpregnant cows were immediately eliminated from the herd and the pregnant cows were isolated and eliminated after parturiation. The calves with colostral antibodies were kept in the herd. There were no seropositive animals between the 6 to 12 months old calves and the heifers. The animals were monitored serologically every 3 months for 21 months and afterwords in 2 semestral intervals. The seropositive nonpregnant, pregnant and the nursing cows were the source of BHV-1 infecction. In order to maintain a BHV-1 free herd, measurements of control had been taken, as the utilization of virus-free semen, quarantine when animals were introduced into the herd, and semestral serological surveys. Through these measurements the farm has been BHV-1 free for 18 months.

Effect of short term non-protein nitrogen feeding for superovulated beef cows without previous adaptation and at different periods of the oestrus cycle.

The aim of this study was to evaluate the effects of short term non-protein nitrogen feeding at different periods of the oestrus cycle in superovulated cows, without previous adaptation, on yield, quality and development degree of recovered embryos. A total of sixty-eight Nelore cows were distributed in three groups: the control group (C) and two groups with urea supply before (UB; urea supply from day -5 to day 0) and after (UA; supply from day 0 to day 5) artificial insemination. Animals were kept grazing and received 3.0 kg/animal/day of concentrate during 16 days. Two concentrates were formulated and the total diets (concentrate and estimate forage intake) showed 12.0% (control diet) and 14.6% (non-protein diet) of crude protein. Animals were synchronized, superovulated and inseminated. The embryos were collected and analysed seven days (day 7) after insemination (day 0). Blood samples were collected on days -5, 0 and 5 to determine concentration of plasmatic urea nitrogen, glucose, insulin and progesterone. The time of urea supply affected average plasmatic urea nitrogen concentration on days -5, 0 5 but it did not affect concetrations of glucose, insulin and progesterone. The moment of urea inclusion had effect on compact morula percentage in relation to the total number of structures (UB = 51.4 vs. UA = 15.3%), to the total number of fertilized oocytes (UB = 62.5 vs. UA = 30.6%) and to the total number of viable embryos (UB = 68.8 vs. UA = 38.6%). In the after insemination group of urea supply there was 70.2% of reduction on compact morula proportion over the total structures in relation to the group that received urea before insemination. Non-protein nitrogen feeding immediately after insemination promotes faster rates of embryo development.

Slow-release urea in supplement fed to beef steers

Replacing regular urea (RU) by slow-release urea (SRU) at two levels of non-protein nitrogen (NPN) in concentrate, offered with low-quality roughage, was evaluated in beef steers on dry matter intake (DMI), ruminal fermentation parameters, plasma urea nitrogen (PUN), total tract apparent digestibility of diets and in situ degradability of nitrogen sources. Eight ruminally cannulated steers were allocated into two 4x4 Latin squares, totalizing four treatments: 40 NPN/0 SRU: 40% of concentrate crude protein (CP) as NPN, resulting from 0% of SRU and 100% of RU; 40 NPN/50 SRU: 40% of concentrate CP as NPN, resulting from 50% of SRU and 50% of RU; 40 NPN/100 SRU: 40% of concentrate CP as NPN, resulting from 100% of SRU and 0% of RU; 80 NPN/100 SRU: 80% of concentrate CP as NPN, resulting from 100% of SRU and 0% of RU. Results showed that partial substitution of regular urea by slow-release urea did not alter dry matter intake, pattern of ruminal fermentation or plasma urea nitrogen concentrations and increased the total tract apparent digestibility of crude protein in steers diets. The increase in non-protein nitrogen content in crude protein of the concentrate could compromise feed intake and the efficiency of nutrient utilization in the steers fed complete diets based on low quality forage.