Macrominerals and trace element requirements for beef cattle

Eighty-seven Nellore animals were utilized in this study to estimate net requirements for the maintenance and growth of beef cattle as well as the retention coefficients of 13 minerals: macrominerals (Ca, P, Mg, K, Na, and S) and trace elements (Cu, Fe, Mn, Se, Zn, Co, and Cr). The net requirements for maintenance and the true retention coefficient were estimated by using the regression between apparent retention and intake for each mineral. The net requirement for maintenance (μg/kg BW) and retention coefficients (%) were 163 and 85 for Cu, 2,097 and 53 for Fe, 32.3 and 24 for Mn, 3.72 and 48 for Se, 669 and 0.80 for Zn, 18.4 and 86 for Co, and 22.9 and 78 for Cr. The dietary requirements of macrominerals (g/kg DMI) were 5.12 for Ca, 2.38 for P, 0.96 for Mg, 2.40 for K, 0.79 for Na, and 1.47 for S. This is the first study using Nellore cattle to estimate mineral requirements; considering that Nellore cattle are the most common breed in Brazil and that Brazil is a major beef producer globally, this knowledge can help producers to improve animal performance by supplying the correct amount of minerals

Construção e validação de modelos de regressão a partir de espectros NIR para predição da composição da cana-de-açúcar, farelo de soja e fubá de milho

Objetivou-se desenvolver e avaliar modelos de regressão para a predição da composição química da cana-de-açúcar, farelo de soja e fubá de milho por NIR portátil aliado a técnicas quimiométricas. Foram utilizadas 95 amostras de cana-de-açúcar, 92 amostras de farelo de soja e 120 amostras de fubá de milho. Após a moagem das amostras, foi realizada aquisição dos espectros de cada amostra. Os valores referência foram obtidos através de análises químicas convencionais. Para construção dos modelos, foi utilizada a regressão por quadrados mínimos parciais e a validação cruzada leave one out. Os modelos com menor raiz quadrada do erro quadrático médio da validação cruzada foram submetidos a validação externa. Para avaliar a qualidade de ajuste dos modelos, os valores preditos foram comparados com os valores obtidos pelos métodos laboratoriais convencionais. Os modelos construídos estimaram corretamente todos os constituintes avaliados para a cana-de-açúcar, farelo de soja e fubá de milho (P ≥ 0,056). Os modelos construídos para predição dos teores de amostra seca em estufa a 55°C (ASA) e a 105°C (ASE), matéria seca total (MS), matéria orgânica (MO), fibra insolúvel em detergente neutro (FDN), FDN corrigida para cinzas e proteína (FDNcp), proteína insolúvel em detergente neutro (PIDN), fibra insolúvel em detergente ácido (FDA), proteína bruta (PB), carboidratos não fibrosos (CNF) e nutrientes digestíveis totais (NDT) da cana-de-açúcar; ASE, MO, FDN, FDA, FDN indigestível (FDNi), PB, NDT e amido de farelo de soja; e ASE, PB do fubá de milho apresentaram elevada acurácia e precisão (R2 ≥ 0,50 e CCC ≥ 0,60). Contudo os modelos construídos para predição dos teores de cinzas insolúveis em detergente neutro (CIDN) da cana-de-açúcar; extrato etéreo (EE) e CIDN do farelo de soja; e FDN, FDNi, CIDN, CNF e EE do fubá de milho foram acurados, porém pouco precisos (R2 ≥ -0,04 e CCC ≥ 0,03). Conclui-se que os modelos de regressão por NIR portátil estimaram acuradamente e, portanto, são recomendados para estimar a composição química da cana-de-açúcar, farelo de soja e fubá de milho

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Performance, enteric methane production, efficiency of use of energy, muscle protein metabolism and nutrient requirements of growing crossbred Holstein × Zebu heifers fed corn silage or sugar cane

O presente trabalho foi desenvolvido a partir de dois experimentos com o objetivo de avaliar o efeito de dietas contendo silagem de milho ou cana-de-açúcar com 30 ou 50% de concentrado sobre desempenho, características de carcaça, produção de metano entérico, eficiência de utilização da energia, metabolismo proteico muscular e estimar as exigências nutricionais de energia e proteína bem como as eficiências de utilização da energia e proteína metabolizável para ganho de peso de novilhas F1 Holandês × Zebu em crescimento. No experimento 1 foram utilizadas 16 novilhas F1 Holandês × Zebu com peso inicial de 218 ± 36,5 kg e idade média de 12 ± 1 meses, às quais foram distribuídas as dietas em delineamento inteiramente casualizado em esquema fatorial 2 x 2, sendo dois volumosos (silagem de milho e cana-de-açúcar) e dois níveis de concentrado (30 e 50%) com base na matéria seca total das dietas. O experimento teve duração total de 112 dias. Os animais alimentados com dietas à base de silagem de milho (SM) ou com 50% de concentrado apresentaram maior (P0,05), sendo maior relação ED:NDT observada para as dietas à base de SM. A eficiência de conversão da ED em energia metabolizável (EM:ED) não foi influenciada pelo tipo de volumoso ou nível de concentrado na dieta (P>0,05), contudo, o valor médio observado para esta relação está acima dos propostos pelos principais sistemas de avaliação de alimentos e exigências nutricionais de ruminantes. Conclui-se que dietas à base de SM permitem melhor desempenho para novilhas Holandês × Zebu em relação às dietas utilizando CA, assim como o viiaumento no nível de concentrado também melhora o desempenho de animais em crescimento. O aumento no nível de concentrado nas dietas à base de CA permite melhora nas emissões de metano por unidade consumida ou por unidade de ganho. O valor para EM:ED é de aproximadamente 86%. O experimento 2 foi realizado por abate comparativo utilizando-se 20 novilhas F1 Holandês × Zebu, com peso inicial de 218 ± 36,5 kg e idade média de 12 ± 1 meses. Quatro novilhas foram designadas ao grupo referência e as dezesseis restantes foram alimentadas ad libitum, às quais foram distribuídas as dietas em delineamento inteiramente casualizado em esquema fatorial 2 x 2, sendo dois volumosos (silagem de milho e cana-de-açúcar) e dois níveis de concentrado (30 e 50%) com base na matéria seca total das dietas. O experimento teve duração total de 112 dias. As equações obtidas para a estimação das exigências líquidas de energia (EL g ) e proteína (PL g ) para ganho de peso foram: EL g (Mcal/dia) = 0,0685 × PCVZ 0,75 × GPCVZ 1,095 e PL g (g/dia) = 203,8 × GPCVZ - 14,80 × ER, respectivamente. As eficiências de utilização da energia (k g ) e proteína (k) metabolizável para ganho foram de 40,8 e 25,2%, respectivamente. As taxas fracionais de síntese (FSR) e degradação (FDR) não foram influenciadas (P>0,05) pelo tipo de volumoso ou níveis de concentrado, contudo, os animais alimentados com dietas contendo 50% de concentrado apresentaram maior (P0.05) by roughage type offered, wherein higher DE:TDN ratio was observed for CS diets. The DE use efficiency (ME:DE) was not influenced by roughage type or concentrate level in the diet (P>0.05), however, the mean value observed to this efficiency is above that proposed by the principal feed and nutritional requirements evaluation systems of ruminants. It is concluded that CS diets promotes better performance than SC diets for crossbred Holstein × Zebu heifers, as well as the increased level of concentrate improves performance of growing animals. The increased level of concentrate in SC diets decreases methane emissions per consumed or gain unit. The DE:ME value is approximately 86%. The experiment 2 was realized using a comparative slaughter technique. We used 20 F1 crossbred Holstein × Zebu heifers with an initial body weight of 218 ± 36.5 kg and a ixmean age of 12 ± 1 months. Four heifers were slaughter to make up the reference group and the sixteen others were distributed in a completely randomized design, 2 x 2 factorial arrangement, two roughage (corn silage and sugar cane) and two concentrate levels (30 to 50%) on dry matter basis (DM) of total diet, during 112 days. The equations obtained to net energy (NE g ) and net protein (NP g ) requirements for gain were: NE g (Mcal/day) = 0.0685 × EBW 0,75 × EBG 1,095 and NP g (g/day) = 203.8 × EBG - 14.80 × RE, respectively. The efficiency of utilization of metabolizable energy (k g ) and protein (k) for gain were 40.8 and 25.2%, respectively. The fractional synthesis (FSR) and breakdown (FBR) rates were not influenced (P>0.05) by roughage type or concentrate level, however, animals fed diets with 50% of concentrate had higher (P<0.05) daily 3-methyl-histidine excretion, final muscle protein and FSR:FBR ratio. Heifers fed CS diets or with 50% of concentrate had higher muscle protein gain and consequently, fractional growth rate (FGR) than those fed SC diets or with 30% of concentrate (P<0.05), respectively. It is concluded that the net energy and protein requirements for gain of crossbred Holstein × Zebu heifers can be obtained by the equations: NE g (Mcal/day) = 0.0685 × EBW 0,75 × EBG 1,095 and NP g (g/day) = 203.8 × EBG - 14.80 × RE, respectively. The k g and k are, respectively, 40.8 and 25.2%. The FSR and FBR of crossbred Holstein × Zebu heifers are not influenced by roughage type or concentrate level, however, the FGR is increased when these animals are fed with better quality diets, resulting in greater muscle protein gain.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Nellore cows and their calves during the lactation period: performance, intake, milk composition, and total apparent digestibility

An experiment was conducted to evaluate intake and nutrient digestibility, performance, milk composition, and microbial efficiency of Nellore cows and their calves during lactation. Fifteen Nellore cows were fed corn silage and concentrate (85:15). After calving, calves were kept with their dams for 2 months then separated and housed in individual pens adjacent to their dams. Cows were milked every 15 days over 7 months to estimate milk intake of the calves. During lactation, nutrient intake decreased (P  0.05) in either cows or their calves during lactation period. However, nutrient digestibility decreased for calves during this period. Nellore cows produced milk with average of 4.58 % lactose, 5.61 % fat, and with milk protein increasing from 3.6 to 4.0 % as lactation progressed

Effect of phase-feeding crude protein on performance and carcass characteristics of crossbred beef bulls: an application to reduce nitrogen compounds in beef cattle diets

Beef cattle (24) with an average initial body weight of 417 ± 54 kg were assigned in a 2 × 2 factorial design with six repetitions. The factors studied were two levels of CP: 11 (low CP) or 13 % (high CP) in the initial feedlot phase (days 1–36) and in the final phase (days 37–72). After 36 days, half of the bulls fed with each level of CP were selected to reverse the CP level. No interaction was observed (P > 0.05) between the level of protein in the initial and final phases on the intake of the nutrients evaluated. There was no effect (P > 0.05) of the protein levels in the initial and final phases on intake of dry matter, organic matter, CP, non-fiber carbohydrates, and total digestible nutrients. No differences were observed among treatments (P > 0.05) for average daily gain (X = 1.99 kg/day) and carcass traits. We conclude that it is possible to feed Holstein-Zebu crossed bulls with an average daily gain of approximately 2 kg using a fixed level of 11 % CP during the entire feedlot period, and this diet is economically viable and environmentally sound

The net requirement for maintenance and the true retention coefficients of trace element minerals for beef cattle.

<p>(<b>A</b>) Copper, (<b>B</b>) Iron, (<b>C</b>) Manganese, (<b>D</b>) Selenium, (<b>E</b>): Zinc, (<b>F</b>) Cobalt, (<b>G</b>) Chromium.</p

The net requirements for maintenance and the true retention coefficients of the macronutrient minerals for beef cattle.

<p>(<b>A</b>) Calcium, (<b>B</b>) Phosphorus, (<b>C</b>) Magnesium, (<b>D</b>) Potassium, (<b>E</b>) Sodium, (<b>F</b>) Sulfur.</p