**1. Introduction**

Whole-plant corn silage is a major ingredient of diets fed to dairy cattle; therefore, producing high-yielding and good-quality corn silage is critical for minimizing production costs in dairy farming systems. The US dairy industry is composed of 9.2 million cows and approximately 4.5 million replacement heifers [1], which consume approximately 60 million (metric) tons of corn silage per year (**Table 1**). The high inclusion of corn silage in diets for dairy cows is attributed to multiple factors. First, corn silage is an attractive feed source because of high yield potential.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

For example, dry matter (DM) yields per acre are substantially greater for corn silage than for alfalfa hay (12,600 and 7200 kg/ha, respectively) [2]. Second, corn silage is also characterized by having high concentrations of energy. Under normal climatic conditions, the corn plant contains a great proportion of starch-containing grains. This starch is highly digestible and therefore is an important source of energy for cattle. Finally, corn silage also provides fiber in ruminant diets. Dairy cows require a minimum amount of dietary fiber to ensure ruminal and whole-animal health [3].

Drought and heat stresses, also known as abiotic stresses, are two common and interrelated environmental factors that frequently affect corn silage yield and quality [4]. The impact of these factors can be substantial. For example, the drought of 2012 reduced US national silage yields by 16.3 % when compared to 2011 (**Figure 1**). This reduction in yield caused the United States an economic loss between \$700 and \$800 million for 2012. This loss does not take into account the overall impact to the dairy industry, such as increases in feed prices for hay and

Environmental Factors Affecting Corn Quality for Silage Production

http://dx.doi.org/10.5772/64381

41

Even though drought stress and heat stress are uncontrollable factors that affect corn silage yield and quality, certain management practices can be utilized to attenuate their potential negative impact. The objective of this chapter is to describe such practices so that crop managers can minimize the negative effects of abiotic stresses in yield and quality of corn silage.

The corn plant is characterized by having a single erect stem that is divided into basic units known as phytomers. Each phytomer consists of a leaf blade, a leaf sheath, a node, an internode, and the axillary bud. Different from most other grasses, the corn plant has two separate inflorescences per plant, the tassel and the ear, which are the male and the female inflorescen‐ ces, respectively. The husks are leaves that cover the ear, where corn kernels develop after pollination. Corn kernels are arranged and inserted in lines on an inner cylinder called the cob,

**Figure 2.** The proportion of grain in the corn plant has a major impact on corn silage yield and nutritional quality. The bigger ear in plant A will result in greater yields of dry matter and greater energy concentration than in plant B.

which is originated from the axillary bud from the phytomers.

corn grain.

**2. The corn plant**

Different crop management practices, such as planting density, nitrogen fertilization rates, harvesting time, or harvesting height, can affect corn silage yield, corn silage quality, or both [4]. One way or another, most of these factors, if not all, can be controlled based on managerial decisions. In addition to controllable factors, there are several uncontrollable environmental factors that can substantially affect the dry matter yield and the nutritional composition of corn used for whole-plant corn silage.


**Table 1.** Consumption and expenditure for corn silage by the US dairy industry.

**Figure 1.** National US corn silage yields (kg/ha, as-fed basis). Spring and summer drought of 2012 will be remembered as one of the "worst agricultural calamities in the United States" [21].

Drought and heat stresses, also known as abiotic stresses, are two common and interrelated environmental factors that frequently affect corn silage yield and quality [4]. The impact of these factors can be substantial. For example, the drought of 2012 reduced US national silage yields by 16.3 % when compared to 2011 (**Figure 1**). This reduction in yield caused the United States an economic loss between \$700 and \$800 million for 2012. This loss does not take into account the overall impact to the dairy industry, such as increases in feed prices for hay and corn grain.

Even though drought stress and heat stress are uncontrollable factors that affect corn silage yield and quality, certain management practices can be utilized to attenuate their potential negative impact. The objective of this chapter is to describe such practices so that crop managers can minimize the negative effects of abiotic stresses in yield and quality of corn silage.
