Degradabilidade ruminal das silagens e produtividade de cultivares de sorgo de tipo forrageiro e granífero

Forages for feeding dairy cows should conciliate the potential for high dry matter yield per unit area, maximizing animal stocking rate, with high nutritive value, which enables decreasing the amount of concentrate feedstuffs per milk unit produced. Eighteen sorghum cultivars were cultivated 0.70 m apart and with 12 plants per linear meter. Plants harvested at the milk-to-dough stage were ensiled in the laboratory. Eleven agronomic and chemical traits were evaluated. Silage samples were incubated in situ and the effective ruminal dry matter degradation (DEF) was calculated assuming a fractional passage rate of -0.04 h-1. Dry matter yield was 13.0 ± 2.3 (mean ± S.D.) t ha-1. The neutral detergent fiber content was 50.3 ± 3.8 and the DEF was 48.8 ± 2.8% (dry matter basis). The average sorghum DEF was 84% of the DEF of a composite sample of 60 corn hybrids simultaneously cultivated, ensiled and ruminally incubated. The 12 forage-type cultivars were taller, more productive, had higher fiber content and lower DEF than the 6 grain and dual purpose-type cultivars. The acid detergent fiber content had the greatest correlation with DEF (r= -0.64). The linear model correlating DEF with productivity was: DEF=54.694 - 0.4449 x t of dry matter ha-1 (r²=0.14). Although there are cultivars that show high productivity and digestibility, it seems to be difficult to conciliate the maximum nutritive value with the maximum productivity of the sorghum crop.Forrageiras para alimentação de vacas leiteiras devem conciliar a alta produção de matéria seca por área, maximizando a taxa de lotação animal, com o alto valor nutritivo, capaz de reduzir a necessidade de alimentos concentrados por litro de leite produzido. Dezoito cultivares de sorgo foram cultivados com espaçamento de 0,70 m e 12 plantas por metro linear. As plantas colhidas ao atingirem o estádio leitoso-pastoso foram ensiladas em laboratório. Onze características agronômicas e químicas foram avaliadas. As silagens foram incubadas in situ e a degradabilidade efetiva da matéria seca no rúmen (DEF) foi calculada assumindo uma taxa de passagem de -0,04 h-1. A produção de matéria seca foi 13,0 ± 2,3 (média ± D.P.) t ha-1. O teor de fibra em detergente neutro foi 50,3 ± 3,8 e a DEF foi 48,8 ± 2,8 (% da matéria seca). A DEF média do sorgo foi 84% da DEF de uma amostra composta de 60 cultivares de milho simultaneamente cultivados, ensilados e incubados no rúmen. Os 12 cultivares do tipo forrageiro foram mais altos, produtivos e fibrosos e tiveram menor DEF que os 6 cultivares graníferos e de duplo propósito. O teor de fibra em detergente ácido foi a característica mais correlacionada à DEF (r=-0,64). O modelo linear correlacionando a DEF à produtividade foi: DEF=54,69 - 0,4449 x t de matéria seca ha-1 (r²=0,14). Apesar de existirem cultivares com alta produtividade e digestibilidade, pode ser difícil conciliar o máximo valor nutritivo com a máxima produtividade na planta de sorgo

Desempenho de sementes de milho em relação à sua localização na espiga Corn seed performance and their position on the ear

As sementes arredondadas do ápice e da base da espiga de milho são separadas das achatadas quanto à espessura durante o beneficiamento, não sendo bem aceitas pelos agricultores. No entanto, no caso de produção de sementes básicas, essas sementes arredondadas têm sido comercializadas em razão de seu alto custo de produção. Com isso, objetivou-se neste trabalho estudar em duas cultivares de milho (AL 25 e BRS 106) o comportamento de sementes localizadas em pontos distintos da espiga (base, meio e ápice) quanto ao seu desempenho. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial 2x3x2 (2 genótipos; 3 localizações na espiga; submetidas ou não ao envelhecimento acelerado) com quatro repetições. A avaliação do desempenho das sementes foi realizada por meio dos testes de germinação, velocidade de germinação, emergência em solo + areia e teste de frio, e a sanidade, por meio do "Blotter test". Conclui-se que as sementes arredondadas localizadas no ápice da espiga apresentam desempenho inferior às sementes da base e do terço médio da espiga.Rounded seeds at the end and at the base of corn ears are separated from the flat ones by thickness during the processing as the former not well being accepted by farmers. Nevertheless, in the case of production of basic seeds, those rounded seeds have been marketed due to their high production cost. So, in this work it was aimed to study, in two corn cultivars AL 25 and BRS 106, the behavior of seeds situated on distinct spots on the ear (base, middle, and tip) regarding their performance. The experimental design was completely randomized in a 2 ' 3 ' 2 factorial scheme (two genotypes, three positions on the ear, submitted or not to accelerated aging) with four replications. Evaluation of performance was done by means of germination tests, germination velocity, emergence on soil + sand, cold test, and sanity by means of the "Blotter test''. It is concluded that a round seeds situated at the tip of the ear performs inferiorly compared to seeds at base and at the middle of the ear

Ruminal silage degradability and productivity of forage and grain-type sorghum cultivars

Forages for feeding dairy cows should conciliate the potential for high dry matter yield per unit area, maximizing animal stocking rate, with high nutritive value, which enables decreasing the amount of concentrate feedstuffs per milk unit produced. Eighteen sorghum cultivars were cultivated 0.70 m apart and with 12 plants per linear meter. Plants harvested at the milk-to-dough stage were ensiled in the laboratory. Eleven agronomic and chemical traits were evaluated. Silage samples were incubated in situ and the effective ruminal dry matter degradation (DEF) was calculated assuming a fractional passage rate of -0.04 h-1. Dry matter yield was 13.0 ± 2.3 (mean ± S.D.) t ha-1. The neutral detergent fiber content was 50.3 ± 3.8 and the DEF was 48.8 ± 2.8% (dry matter basis). The average sorghum DEF was 84% of the DEF of a composite sample of 60 corn hybrids simultaneously cultivated, ensiled and ruminally incubated. The 12 forage-type cultivars were taller, more productive, had higher fiber content and lower DEF than the 6 grain and dual purpose-type cultivars. The acid detergent fiber content had the greatest correlation with DEF (r= -0.64). The linear model correlating DEF with productivity was: DEF=54.694 - 0.4449 x t of dry matter ha-1 (r²=0.14). Although there are cultivars that show high productivity and digestibility, it seems to be difficult to conciliate the maximum nutritive value with the maximum productivity of the sorghum crop