The objective of the present study was to perform a meta-analysis that compared the chemical composition of corn silage produced for different experimental purposes, i.e., by research groups that studied corn silage (SCS) or by research groups that only used corn silage (UCS) as a form of roughage. We analyzed 203 papers that were published between January 1994 and December 2014 and contained a total of 647 treatments and the analysis of 1701 silos. We found a significant difference (P < 0.0001) in the dry matter (DM) content of SCS silage (33.00%) and that of UCS silage (30.64%). The DM contents of neutral detergent fiber for the SCS and UCS silage were high (54.72 and 55.14% DM, respectively) but were not significantly different from one another (P = 0.5936), and the acid detergent fiber content of the UCS silage (31.04% DM) was higher than that of the SCS silage (29.65%, P = 0.0214), which indicated that the UCS silage was less digestible than the SCS silage. This was also corroborated (P = 0.0064) by the mean content of total digestible nutrients (64.18% DM) in the UCS silage, which likely results from the lower level of care taken when using standard silage production methods, compared to that taken by SCS researchers. Therefore, we concluded that the corn silage produced by research groups in Brazil are not analyzed in full and that, as a result, there is a paucity of important information, such as the content of organic acids. In addition, we also found that corn silage produced in Brazil contains a high level of neutral detergent fiber. Key words: Starch. Carbohydrate. Fiber. Ruminant. Conserved roughage. Zea mays. ResumoObjetivou-se analisar metanaliticamente a composição bromatológica de silagens de milho, estudadas ou utilizadas em dietas para ruminantes, em condições experimentais brasileiras. Foram utilizados artigos publicados entre janeiro de 1994 e dezembro de 2014, totalizando 203 artigos científicos com 647 tratamentos, envolvendo a análise de 1.701 silos. Observou-se diferença (P < 0,0001) no teor de matéria seca (MS) encontrado nas silagens entre pesquisas que estudam especificamente silagem de milho (ESM, de 33,00% de MS), para as que utilizam silagem de milho como suporte em outras avaliações científicas USM, 30,64% de MS). Os teores de fibra em detergente neutro são elevados para ESM (54,72% da MS) e para USM (55,14% da MS), não havendo diferença (P=0,5936). As USM apresentam valores maiores (P = 0,0214) de fibra em detergente ácido (FDA) (31,04% da MS), ou seja, fornecem volumoso de menor digestibilidade que as ESM. Este fato é também corroborado (P = 0,0064) pelo nível médio de nutrientes digestíveis totais (NDT) (64,18% da MS) nos estudos USM, pois geralmente não há o mesmo cuidado com as premissas básicas de produção de silagem, comparado com o grupo ESM cujas silagens apresentaram em média 29,65% de FDA e 66,79% de NDT. As silagens de milho de planta inteira produzidas em condições experimentais no Brasil não são analisadas por completo, faltam informações imprescindíveis como...

Our objective was to quantify the relationship between seasons of the year, milk production, and milk composition of a dairy farm based on data for 48 consecutive months, using multivariate statistical analyses. The dataset contained information on productive indexes and milk composition from the bulk tank milk, which was measured from milk samples, collected monthly and used to determine the total dry extract and defatted dry extract, lactose, fat, protein, somatic cell count, and total bacterial count. Seasons of the year and milk production/hectare were also considered. Factor, cluster, and discriminant analysis were used to study the relationships between the above-mentioned variables. A positive relationship was noted between season and total dry extract, defatted dry extract, milk fat, and protein, with higher values being observed in winter and spring. Similarly, a positive relationship was noted between season and milk production/hectare, lactose content, with an increase in milk production and lactose content in winter and spring, which was negatively related to the somatic cell count and total bacterial count. Milk production and composition varied mainly with seasons. Multivariate analyses facilitated a better understanding of the relationship between milk production and composition on this dairy farm.

The objective of this study was to conduct a meta-analysis of scientific publications from January 1994 to December 2014, to evaluate the chemical composition of corn plants, green forage, and silages of three different types of maize hybrids (simple, double, and triple) used in experimental conditions in Brazil. The sub-bases Corn Cultivation and Green Fodder were composed of 49 experiments, consisting of 481 treatments, and the sub-base Silage consisted of 24 studies composed of 163 treatments, involving 478 silos. In the Corn Cultivation sub-base, the variables of spacing, plant height, grain yield, organic matter content, and total carbohydrates of maize silage differed (P < 0.05) according to the hybrid type. The number of corn plants per hectare, number of spikes per plant, and the levels of neutral detergent fiber, acid detergent fiber, hemicellulose, and lignin did not differ (P > 0.05) according to the hybrid type. In the Green Forage sub-base (ensilage), the main difference (P < 0.05) was regarding the in vitro dry matter digestibility, whereby the triple hybrids (59.38%) had lower values than the simple (73.05%) and double (72.74%) hybrids. In the Silage sub-base, the variables of organic matter, total carbohydrates, cellulose, in vitro dry matter digestibility, and pH differed (P < 0.05) according to the hybrid type. While the variables dry matter, non-fibrous carbohydrates, neutral detergent fiber, acid detergent fiber, hemicellulose, lignin, total digestible nutrients, ethereal extract, crude protein, and ammonium nitrogen did not differ (P > 0.05) according to the hybrid type. The variability in the determination of parameters, such as dry matter yield, dry matter content, and non-fibrous carbohydrates of corn silage, and the non-determination of the starch content demonstrated that the chemical compositions of Brazilian corn silage have not yet been fully clarified. The types of maize hybrids (simple, double, and/or triple) mainly differ in terms of grain production. In many situations, the silage processes are not conducted in an ideal way, and the differences as a function of the maize plants (type of hybrid) are minimized due to losses during the ensiling process.

The objective of this study was to conduct a meta-analysis of scientific publications from January 1994 to December 2014, to evaluate the chemical composition of corn plants, green forage, and silages of three different types of maize hybrids (simple, double, and triple) used in experimental conditions in Brazil. The sub-bases Corn Cultivation and Green Fodder were composed of 49 experiments, consisting of 481 treatments, and the sub-base Silage consisted of 24 studies composed of 163 treatments, involving 478 silos. In the Corn Cultivation sub-base, the variables of spacing, plant height, grain yield, organic matter content, and total carbohydrates of maize silage differed (P < 0.05) according to the hybrid type. The number of corn plants per hectare, number of spikes per plant, and the levels of neutral detergent fiber, acid detergent fiber, hemicellulose, and lignin did not differ (P > 0.05) according to the hybrid type. In the Green Forage sub-base (ensilage), the main difference (P < 0.05) was regarding the in vitro dry matter digestibility, whereby the triple hybrids (59.38%) had lower values than the simple (73.05%) and double (72.74%) hybrids. In the Silage sub-base, the variables of organic matter, total carbohydrates, cellulose, in vitro dry matter digestibility, and pH differed (P < 0.05) according to the hybrid type. While the variables dry matter, non-fibrous carbohydrates, neutral detergent fiber, acid detergent fiber, hemicellulose, lignin, total digestible nutrients, ethereal extract, crude protein, and ammonium nitrogen did not differ (P > 0.05) according to the hybrid type. The variability in the determination of parameters, such as dry matter yield, dry matter content, and non-fibrous carbohydrates of corn silage, and the non-determination of the starch content demonstrated that the chemical compositions of Brazilian corn silage have not yet been fully clarified. The types of maize hybrids (simple, double, and/or triple) mainly differ in terms of grain production. In many situations, the silage processes are not conducted in an ideal way, and the differences as a function of the maize plants (type of hybrid) are minimized due to losses during the ensiling process.