Nutritive value of maize silage in relation to dairy cow performance and milk quality

Abstract

Maize silage has become the major forage component in the ration of dairy cows over the last few decades. This review provides information on the mean content and variability in chemical composition, fatty acid (FA) profile and ensiling quality of maize silages, and discusses the major factors which cause these variations. In addition, the effect of the broad range in chemical composition of maize silages on the total tract digestibility of dietary nutrients, milk production and milk composition of dairy cows is quantified and discussed. Finally, the optimum inclusion level of maize silage in the ration of dairy cows for milk production and composition is reviewed. The data showed that the nutritive value of maize silages is highly variable and that most of this variation is caused by large differences in maturity at harvest. Maize silages ensiled at a very early stage (dry matter (DM) < 250 g kg(-1)) were particularly low in starch content and starch/neutral detergent fibre (NDF) ratio, and resulted in a lower DM intake (DMI), milk yield and milk protein content. The DMI, milk yield and milk protein content increased with advancing maturity, reaching an optimum level for maize silages ensiled at DM contents of 300-350 g kg(-1), and then declined slightly at further maturity beyond 350 g kg(-1). The increases in milk (R(2) = 0.599) and protein (R(2) = 0.605) yields with maturity of maize silages were positively related to the increase in starch/NDF ratio of the maize silages. On average, the inclusion of maize silage in grass silage-based diets improved the forage DMI by 2 kg d(-1), milk yield by 1.9 kg d(-1) and milk protein content by 1.2 g kg(-1). Further comparisons showed that, in terms of milk and milk constituent yields, the optimum grass/maize silage ratio depends on the quality of both the grass and maize silages. Replacement of grass silage with maize silage in the ration, as well as an increasing maturity of the maize silages, altered the milk FA profile of the dairy cows, notably, the concentration of the cis-unsaturated FAs, C18:3n-3 and n-3/n-6 ratio decreased in milk fat. Despite variation in nutritive value, maize silage is rich in metabolizable energy and supports higher DMI and milk yield. Harvesting maize silages at a DM content between 300 and 350 g kg(-1) and feeding in combination with grass silage results in a higher milk yield of dairy cows.

The utilisable value of the maize plant (biomass) for silage

“…The lowest contents of NDF, ADF and ADL were determined in the maize hybrid ZP 434 that is a dent with a hard endosperm. Obtained results are in accordance with results more recently published by foreign authors who had recorded higher contents of NDF, ADF and ADL in morphological parts, but also in the whole plant of dent maize in relation to hard forms of dent maize (Ferreira et al, 2013 andKhan et al, 2015).…”

Chemical composition and in vitro digestibility of whole-crop maize fertilized with synthetic fertilizer or digestate and harvested at two maturity stages in Boreal growing conditions

“…In their two year study at northern latitudes (56 o N-59 o N) the DM content of three forage maize hybrids varied between 160-370 g kg -1 at approximately 150 DAS. Khan et al (2015) concluded that the DM intake, milk yield and milk protein content increased with advancing maturity, reaching an optimum level for maize ensiled at DM contents of 300-350 g kg , and then declined slightly at further maturity beyond 350 g kg -1…”

“…This agrees with the in vitro results of Lynch et al (2012) between 126 DAS and 153 DAS while the further delay of harvest to 174 DAS decreased digestibility. Many investigations have revealed the negative effects of increasing maize maturity on digestibility, mainly when maize is harvested with high DM content (≤ 350 g DM kg -1 ; Khan et al 2015). This indicates changes in the cob/stover ratio and changes in the digestibility of the nutrient components while the profile of digestibility changes differ among hybrids (Lynch et al 2012, Khan et al 2015.…”

“…Many investigations have revealed the negative effects of increasing maize maturity on digestibility, mainly when maize is harvested with high DM content (≤ 350 g DM kg -1 ; Khan et al 2015). This indicates changes in the cob/stover ratio and changes in the digestibility of the nutrient components while the profile of digestibility changes differ among hybrids (Lynch et al 2012, Khan et al 2015. However, no reduction in OM digestibility was recorded when four maize silages containing between 220 and 380 g DM kg -1 were fed in dairy cow diets comprising 420 g maize silage kg -1 total DM intake .…”

“…Whole-crop maize (Zea mays L.) is an important and widely investigated forage for ruminants (Bal et al 1997, Jensen et al 2005, Cone et al 2008, Khan et al 2015, and is also used as an energy crop (Ericsson andNilsson 2006, Seleiman et al 2013). It has been used to produce silage because of its high nutritive value and potential for high yield in a single harvest (e.g.…”