Feedlot performance, feeding behavior and rumen morphometrics of Nellore cattle submitted to different feeding frequencies

Owing to the lack of information in the literature about the ideal feeding frequency adopted by feedlot systems, this study was designed to evaluate the effect of different feeding frequencies on performance, carcass traits, feeding behavior and rumen morphometrics of Nellore cattle. Forty-eight yearling bulls were housed in individual pens with an average initial body weight of 358.2 kg. The experiment was designed as a completely randomized block and the treatments were the feeding of cattle one, two, three, or four times daily (n = 12 per treatment). Orthogonal contrasts were used to assess linear, quadratic and cubic relationship between feeding frequency and the dependent variable. As feeding frequency increased, final body weight (p = 0.03) and average daily gain (p = 0.01; one: 0.98 kg d1; two: 0.96 kg d1; three: 1.18 kg d1; four: 1.14 kg d1) increased linearly and the feed:gain ratio decreased (p = 0.02). Also, as feeding frequency increased, hot carcass weight was affected cubically (p = 0.01; one: 246.9 kg; two: 243.0 kg; three: 263.1 kg; four: 258.1 kg). During the adaptation period dry matter intake variation was affected cubically (p 0.05; one: 16 %; two: 23 %; three: 14 %; four: 16 %). Increases in feeding frequency affected papillae height (p 0.01) and papillae surface area (p 0.01) cubically, as well as producing increases in the mitotic index (p = 0.05; one: 9 %; two: 11 %; three: 13 %; four: 13 %) and cells in proliferation (p = 0.05) linearly. Thus, Nellore yearling bulls should be fed three times daily in feedlot operations.

Feedlot performance, feeding behavior and rumen morphometrics of Nellore cattle submitted to different feeding frequencies

Owing to the lack of information in the literature about the ideal feeding frequency adopted by feedlot systems, this study was designed to evaluate the effect of different feeding frequencies on performance, carcass traits, feeding behavior and rumen morphometrics of Nellore cattle. Forty-eight yearling bulls were housed in individual pens with an average initial body weight of 358.2 kg. The experiment was designed as a completely randomized block and the treatments were the feeding of cattle one, two, three, or four times daily (n = 12 per treatment). Orthogonal contrasts were used to assess linear, quadratic and cubic relationship between feeding frequency and the dependent variable. As feeding frequency increased, final body weight (p = 0.03) and average daily gain (p = 0.01; one: 0.98 kg d1; two: 0.96 kg d1; three: 1.18 kg d1; four: 1.14 kg d1) increased linearly and the feed:gain ratio decreased (p = 0.02). Also, as feeding frequency increased, hot carcass weight was affected cubically (p = 0.01; one: 246.9 kg; two: 243.0 kg; three: 263.1 kg; four: 258.1 kg). During the adaptation period dry matter intake variation was affected cubically (p 0.05; one: 16 %; two: 23 %; three: 14 %; four: 16 %). Increases in feeding frequency affected papillae height (p 0.01) and papillae surface area (p 0.01) cubically, as well as producing increases in the mitotic index (p = 0.05; one: 9 %; two: 11 %; three: 13 %; four: 13 %) and cells in proliferation (p = 0.05) linearly. Thus, Nellore yearling bulls should be fed three times daily in feedlot operations.(AU)

Unexpected chromosomal alterations in Tayassu tajacu (Artiodactyla: Tayassuidae) in captivity / Alterações cromossômicas inesperadas em Tayassu tajacu (Artiodactyla: tayassuidae) de cativeiros

Os animais silvestres têm sido utilizados como bioindicadores quando o ambiente é exposto a estressores químicos. Em geral, os agentes químicos podem induzir às alterações cromossômicas dos tipos falhas e quebras. Tayassu tajacu, é uma espécie aparentada dos porcos verdadeiro e apresenta uma grande estabilidade cariotípica. As únicas alterações descritas são em relação a forma do cromossomo X. Foram observadas falhas e quebras cromossômicas durante as análise citogenética. Estas alterações foram detectadas em cromossomos autossômicos. Levantamentos realizados na literatura associados as dados observados nos exemplares estudados, indicam um vermífugo, a base de ivermectina, como o possível causador dessas alterações cromossômicas. (AU)

Wild animals have been used as bioindicators in situations in which the environment was exposed to chemical agents. In general, chemical agents may induce chromosomal aberrations, such as breaks and gaps. The peccary, Tayassu tajacu is a pig relative that exhibits a very stable karyotype with the only described alterations being of the form of the X chromosome. Chromosomal gaps and breaks were observed at high frequencies during cytogenetics analyses. These alterations were observed in the chromosomes autossomics. Reviews of the literature and of the data described herein suggests that an vermifuge, the ivermectin base, was the most likely cause of these chromosomal alterations. (AU)