Dimas C. Rocha

Efeito da sincronização e da indução de estros em novilhas sobre a prenhez e o índice de repetição de crias na segunda estação reprodutiva

This research was aimed at verifying the pregnancy rate in beef heifers submitted to a protocol for estrus induction and synchronization on the parturition period and its effect on the repetition of pregnancy at the second reproductive season. The experimental animals where composed of 194 Hereford and Braford heifers divided in two groups. The treatment group included a protocol of estrus observation and synchronization and fixed-time insemination (FTAI). The control group was submitted to a conventional artificial insemination management, with estrus observation and insemination in the next turn. Both groups were submitted to a natural mating period with clean-up bulls. The heifers were also observed as primiparous on the next reproductive season. The pregnancy rate was 91.7% in the first season for both groups. In the treatment group, 82% of the treated cows calved on the first 40 days of the groups calving season, against 51.7% of the control animals, resulting in a better conception rate in treated heifers (73 vs. 55%) in the second breeding season. The estrus synchronization and FTAI management on the first breeding season of beef heifers produce better pregnancy results also on the second breeding season.

Mineral deficiencies in beef cattle from southern Brazil

Os minerais sao de grande importância no metabolismo dos bovinos, tendo impacto no desempenho produtivo e reprodutivo dos animais. Atualmente ha poucos relatos no Rio Grande do Sul com relacao ao diagnostico de deficiencias minerais mediante a analise de fluidos biologicos em animais a campo. A regiao da Depressao Central do Rio Grande do Sul e caracterizada pela producao extensiva de gado de corte em campo nativo com manejo precario da suplementacao mineral, apresentando baixos niveis de alguns minerais nas pastagens. O objetivo do presente trabalho foi diagnosticar possiveis deficiencias minerais em vacas de corte na regiao da Depressao Central mediante a dosagem de indicadores minerais em fluidos biologicos e na pastagem. Foram determinadas concentracoes de fosforo, calcio, cobre, zinco, glutation peroxidase (como indicador de selenio) e tiroxina (como indicador de iodo) no sangue, sodio e potassio na saliva e sodio, e calcio, fosforo, potassio, zinco, cobre, sodio e ferro na pastagem. Foram estudadas quatro propriedades em Cachoeira do Sul, em quatro momentos do ciclo reprodutivo: periodo de servico (inseminacao artificial), periodo de repasse de touros, final da gestacao e inicio da lactacao, num total de 112 animais. O perfil mineral indicou deficiencia marginal de fosforo, cobre, iodo e selenio. O calcio serico apresentou-se diminuido, possivelmente relacionado com o baixo conteudo de proteina na pastagem. Os periodos mais afetados foram o final da gestacao e o inicio da lactacao indicando que essas categorias de producao tem maior exigencias metabolicas.

Desempenho e características de carcaça de novilhos terminados em pastagem de aveia preta e azevém anual com diferentes níveis de suplementação energética

The impact of energy supplementation on the performance and carcass caracteristics of 24 Aberdeen Angus x Charolais steers grazing an annual ryegrass (Lollium multiflorum L.) and Oats (Avena strigosa Schreb) pasture managed in order to avoid constrains to animal performance was evaluated. Treatments were levels of supplementation of 0; 0.4; 0.8 and 1.2% BW with a corn and mineral based supplement. Animals were slaughtered as they achieve 4,5mm of fat cover in the rump (P8) evaluated ultrasonography. No differences were observed in fat deposition, measured in live animals with ultrasound at the end of performance period, and in live weight gain, which showed average values of 3,9mm and 1,54kg d-1 respectively. Blood serum levels of urea were linearly decreased and cholesterol linearly increased by energy supplementation, with no differences in the serum levels of glucose and triglicerides. Energy supplementation linearly increased the killing-out proportion and carcass weight gain, but no differences were observed on the rib eye area, slaughter weight and hot carcass weight, wich averaged 67,85cm2, 438,95kg e 227,75kg. Increasing the levels of supplementation resulted in higher killing-out proportion and higher carcass daily gains, without changes in performance and carcass parameters evaluated.