I don’t like interacting, but it’s necessary: a brief overview of factorial experiments in animal science

The factorial experiments are useful in animal science, as they allow us to evaluate how different causative factors affect directly the animal responses and, mostly important, how the factors can interfere with each other on that responses. The animal production is naturally an interactive process. Therefore, interactions must be an important aspect to be considered when we look at a better understanding of nutritional and metabolic aspects of animal production. In this overview, I present the most basic aspects of factorial experiments applied do animal science and some ways to avoid the most common mistakes that can be made when carrying out this kind of experiment

Variations in Methods for Quantification of Crude Ash in Animal Feeds

Background Crude ash is categorized as an empirical method playing an important role in the nutritional interpretation of animal feeds, allowing indirect estimation of total organic matter (OM). Objective Our objective was to evaluate variations in laboratory procedures for crude ash quantification regarding physical parameters (i.e., time, temperature) and ashing aids and their influences on crude ash, repeatability, and discrimination power among feeds. Methods The "control" method was based on a simple ignition time of 3 h at 550 degrees C. The variations are briefly described: increasing ashing time to 6 h; increasing temperature to 600 degrees C; and using two 3 h ignition cycles at 550 degrees C with ashing aids inclusion between them: fresh air supply, fresh air supply plus distilled water, and fresh air supply plus hydrogen peroxide. A color evaluation was also performed using a colorimetric technique. Twenty-four study materials from eight different feed types were evaluated. Results The crude ash results differed among the method variations, but a consistent decrease in the estimates was observed when liquid aids were applied, which also improved repeatability. Ash residues did not present a consistent color pattern among methods, but the residues were darker when the control method was applied. Conclusion The method of obtaining ash residues in animal feeds based on 550 degrees C x 3 h does not have enough robustness and may overestimate crude ash in some feeds. Adjustments in either ignition time or temperature might improve crude ash test results, but the best test results are obtained using liquid ashing aids between two ignition cycles

Does frequency of protein supplementation affect performance of cattle under grazing in tropical pastures?

Our objective was to evaluate the effects of protein supplementation frequency on performance and voluntary intake of cattle under grazing in tropical pastures by using a meta-analytical approach. The dataset used to evaluate the voluntary intake was compiled from 18 experiments carried out in Brazil between 2009 and 2021, totaling 75 treatment means. In order to evaluate the animal performance, treatment means were collected from 19 experiments carried out in Brazil between 2003 and 2018, totaling 69 treatment means. The data were analyzed using meta-analysis techniques, considering the random effect of the experiments on the model parameters. There was no effect of supplementation (P > 0.11) or supplementation frequency (P > 0.18) on forage intake and dietary digested organic matter content (DOM). On the other hand, supplementation increased (P 0.84). The ADG increased linearly (P 0.05) among supplementation frequencies. The additional weight gain (AWG) caused by supplementation decreased as forage CP increased and became null at 150 g CP/kg dry matter. There was a quadratic pattern (P 0.05). Maximal responses occur when 5.0 g of supplement and 1.14 g of supplemental CP per kg BW were provided. Reducing protein supplementation frequency down to thrice a week does not affect voluntary intake and performance of cattle under grazing in tropical pastures. There is a positive response to protein supplementation on animal performance even with medium to high-quality forages. However, that response decreases as forage CP increases and becomes null at 150 CP/kg dry matter

Biochemical and genetic diversity of carbohydrate-fermenting and obligate amino acid-fermenting hyper-ammonia-producing bacteria from Nellore steers fed tropical forages and supplemented with casein

BACKGROUND: Dietary protein plays a major role in ruminant nutrition, and protein supplementation is a widespread practice among farmers in the tropics. Ruminal bacteria are the main agents of dietary protein and amino acid degradation, yet few studies have focused on the isolation and characterization of hyper-ammonia-producing bacteria in animals fed tropical diets or supplemented with rumen-degradable proteins. This work investigated the bacterial community diversity of the rumen of Nellore steers fed tropical forages, with or without casein supplementation. We also isolated and characterized ruminal bacteria showing high levels of ammonia production. RESULTS: Polymerase chain reaction–denaturing gradient gel electrophoresis analysis indicated no differences in the ruminal bacterial community composition between the control and supplemented animals. Amino acid-fermenting bacteria (n = 250) were isolated from crossbred Nellore steers fed Tifton 85 (Cynodon sp.) using trypticase as the sole carbon and organic nitrogen source in the enrichment and isolation media. The deamination rates in isolates obtained from steers supplemented with casein showed a higher incidence of deamination rates >350 nmol NH(3) mg protein(−1) min(−1) (P < 0.05), whereas isolates obtained from steers without supplementation showed deamination rates <200 nmol NH(3) mg protein(−1) min(−1). Although most isolates (84%) could ferment carbohydrates, none could hydrolyze proteins or use urea to sustain growth. All isolates were sensitive to lasalocid and monensin (1 μmol l(−1)), and similarity analysis of the 16S rRNA sequences indicated a predominance of bacteria from the order Clostridiales, with variable homology (73–99%) to known bacterial species. CONCLUSIONS: These results expand what is known about the biochemical and genetic diversity of hyper-ammonia-producing bacteria, and emphasize the role of carbohydrate-fermenting bacteria in ammonia production in the rumen. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12866-015-0369-9) contains supplementary material, which is available to authorized users

Estratégias de suplementação pré e pós-parto no desempenho e no estado metabólico de vacas de corte em pastejo

The objective of this work was to evaluate the effect of energy-protein supplementation in pre- and postpartum periods on the productive and metabolic responses of grazing beef cows on tropical pasture. A group of 48 multiparous Nellore cows, with an initial gestation period of 6.4 months, body weight (BW) of 514.9 kg, and body condition score (BCS) of 5.4, was distributed in a completely randomized design, in a 2×2 factorial arrangement. The evaluated treatments were: UNS-UNS, unsupplemented during prepartum and postpartum; UNS-SUP, unsupplemented during prepartum and supplemented during postpartum; SUP-UNS, supplemented during prepartum and unsupplemented during postpartum; and SUP-SUP, supplemented during pre- and postpartum. The energy-protein supplement was offered at an amount of 1.5 kg per animal per day. Prepartum supplementation increased average daily gain and BCS at calving. Prepartum supplementation reduced non-esterified fatty acids (NEFA) and increased serum concentrations of total proteins and globulins during postpartum. Postpartum supplementation increased the BCS of cows and BW of calves at the end of the experiment. Postpartum supplementation increased blood concentrations of progesterone, while NEFA decreased. Supplementation with 1.5 kg per day of the energy-protein supplement during the last 84 days of gestation improves productive performance and metabolic status during the pre- and postpartum periods of grazing cows.O objetivo deste trabalho foi avaliar o efeito da suplementação energético-proteica no pré e pós-parto sobre as respostas produtivas e metabólicas de vacas de corte, em pastagem tropical. Um grupo de 48 vacas Nelore multíparas, com tempo de gestação inicial de 6,4 meses, peso corporal (PC) de 514,9 kg e escore de condição corporal (ECC) de 5,4, foi distribuído em delineamento inteiramente casualizado, em arranjo fatorial 2×2. Os tratamentos avaliados foram: UNS-UNS, não suplementado no pré e pós-parto; UNS-SUP, não suplementado no pré-parto e suplementado no pós-parto; SUP-UNS, suplementado no pré-parto e não suplementado no pós-parto; e SUP-SUP, suplementado durante o pré e o pós-parto. O suplemento energético-proteico foi oferecido na quantidade de 1,5 kg por animal por dia. A suplementação pré-parto aumentou o ganho médio diário e o ECC ao parto. A suplementação pré-parto reduziu os ácidos graxos não esterificados (AGNE) e aumentou as concentrações séricas de proteínas totais e globulinas durante o pós-parto. A suplementação pós-parto aumentou o ECC das vacas e o PC dos bezerros ao final do experimento. A suplementação pós-parto aumentou as concentrações sanguíneas de progesterona, enquanto os níveis de AGNE diminuíram. A suplementação com 1,5 kg por dia de suplemento energético-proteico durante os últimos 84 dias de gestação melhora o desempenho produtivo e o status metabólico durante os períodos pré e pós-parto de vacas em pastejo

Comparison of methane production from individual feeds and total diets – an in vitro evaluation

The objective of the current study was to compare methane (CH4) production from the in vitro gas production system by incubating feeds either individually or as mixed total diet. Eleven diets varying in the forage to concentrate ratio were tested. The forages were tropical grass or corn silages and the concentrate mixtures consisted of soybean grain, soybean meal, corn grain, wheat bran, urea and minerals in different proportions. There were three replicates for each diet. Methane production was reported as weighted mean for individual feeds and total diet separately. The mean of CH4 production from total diet was 30.1 mL g-1 dry matter (DM) and 30.8 mL g-1 DM from the weighted mean of individual feeds. There was a weak correlation between weighted CH4 production from individual feeds and complete diet (r = 0.15). It can be concluded that individual feeds cannot be used as a proxy to estimate CH4 production from total mixed diets

Association of virginiamycin and multiple supplement for cattle fed a high-quality tropical forage

The aim of this study was to evaluate the effect of adding virginiamycin to either mineral mixture or multiple supplement on intake, digestion, ruminal fermentation profile, rumen microbial production, blood metabolites, and liver metabolism of zebu heifers fed a high-quality tropical forage. Eight Brahman heifers were assigned to a replicated 4 × 4 Latin Square design. The treatments were: mineral mixture, mineral mixture with virginiamycin, multiple supplement, and multiple supplement with virginiamycin. The basal diet consisted of a high-quality Tifton 85 hay (Cynodom sp.) chopped at 10-cm particle size and fed twice daily. The mineral mixture was provided daily at 120 g/animal. The multiple supplement was formulated to provide 300 g of crude protein (CP)/kg as fed, contained mineral mixture, corn grain, and urea: ammonium sulfate, and was daily provided at 200 g/animal. The mineral mixture and multiple supplement provided the same daily amount of minerals. The amount of supplemental virginiamycin was based on a maximum theoretical response on animal performance (50 mg/100 kg body weight) and daily mixed to the supplements types. The treatments were compared according to a 2 × 2 factorial arrangement (mineral mixture and multiple supplement, with or without virginiamycin). The virginiamycin supplementation did not alter either voluntary intake or digestibility (P≥0.44). Using the multiple supplement decreased forage (

Relações de troca com efeito tecnológico no mercado doméstico de arroz, milho, café e soja

The objective of this work was to evaluate, by means of the exchange rate, the profitability of two products directed toward the domestic market and two export products. Other objective was to identify productivity growth compensated the decrease of prices. The geometric rates of the production, area and productivity growth were estimated. The exchange rate was estimated by the relation between the index of the inputs prices and the index of the product prices. The results show a great trend of deterioration of the exchange terms for all the analyzed products. Evidenced that these effects more was been accented for rice and maize. Such behavior associates it the fact of the rice cultures and of maize to be destined to the domestic market, its demands have been not elastic in relation to the coffee and soy cultures.Terms of exchange, Grains, Inputs, Prices, Productivity, Income, Productivity Analysis,

Questão agrária e desenvolvimento econômico e social nas regiões Norte e Noroeste fluminense

The research has as objective to analyze the evolution of the agrarian structure, and the behavior of the economic and social development indicators, for the North and Northwest regions of the Rio de Janeiro state. Moreover, it searchs to verify if the land distribution is an important variable in the explanation of the divergences between the degree of economic development of the cities. The results show that, for the considered regions, the differences in the agrarian structure, separately, can not explain the differences in the degree of economic and social development. The size of the population, in turn, seems to be an important variable in this process. This can be associated to the greater potential demand, what is attractive the private investments. Another reason is, possibly, the greatest politics power, due to the size of the electorate, what can influence in the destination of the public investments.Agrarian structure, Economic and social development, Royalties, Community/Rural/Urban Development,