**4. Discussion**

without inoculant, one-hour wilting precluded the rise of pH, but two-hour wilting did not (p < 0.05), while with the addition of inoculant, wilting led to rises in pH (p < 0.05), in phases

**Figure 2.** Classes of alfalfa and orchard grass silages harvested at 08:00 or 14:00, submitted to 0, 1 or 2 h of wilting and

DM d−<sup>1</sup> 5.8 17.2 16.2

**Class 1 2 3** Harvest at 14:00 proportion (%) within class 89% 26% 17% Harvest at 08:00 proportion (%) within class 11% 74% 83% Wilting 75% 58% 83% Inoculant 46% 50% 67% Events rainfall 11% 16% 100% Amount rainfall (mm/6 h) 0.3 0.2 0.7 Evapotranspiration (mm/6 h) 2.5 0.7 0.3 DM % Freshly cut forage 25% 20% 19% DM % Silage 29% 20% 18% pH 4.56 4.80 5.18

Temperature °C 20.4 19.1 19.9

**Table 7.** Attributes of three classes of alfalfa and orchard grass silages harvested at 08:00 or 14:00, wilted 0, 1 or 2 h and

two and three there was no effect of this interaction (p > 0.05).

with or without addition of bacterial inoculant.

CO<sup>2</sup>

116 Forage Groups

Production rate mmol CO<sup>2</sup>

with or without addition of bacterial inoculant.

g−<sup>1</sup>

## **4.1. Properties of forage to be ensiled**

The pH of forage to be ensiled was not affected by treatments and ranged between 6.5 y 7.0 in the scope of results quoted by Coblentz and Muck [4], but somewhat higher than the range between 6.1 and 6.2 reported by Santos and Kung [17]. The results attained in terms of buffering capacity with no effect of treatments, differ from those reported by Zheng et al. [18] who found that wilting resulted in an on average reduction in 5% of the buffering capacity of alfalfa forage; but, the effect of wilting on the buffering capacity is highly dependent on the weather conditions during wilting [4].

As expected from results reported by Tremblay et al. [3] DM content of forage cut in the afternoon was higher than that of forage cut in the morning, which was coupled with higher humidity and lower ambient temperature, solar radiation and wind speed in the morning hours, leading to lower evapotranspiration which concurs with Owens et al. [19]. During morning hours low evapotranspiration is the probable cause of the lack of effect of wilting on DM content of forage to be ensiled; conversely, in forage harvested at 14:00 in phases two and three there was a linear increase in DM content as the wilting time increased.

The content of ASC of fresh forage in phase one did not show significant differences, while in phases two and three forage treatments harvested at 14:00 had higher concentrations of ASC, which was to be expected [3]. On the other hand, the wilting time did not affect the concentration of ASC; on the contrary, Zheng et al. [18] found reductions of 8 and 17% when wilting alfalfa forage for 2 and 4 h.

The NDF content of forage harvested at 14:00 was lower than that of forage harvested at 08:00, probably due to the accumulation of photosynthetic products in the cell content [19]. This represents advantages in terms of the nutritional composition and fermentative characteristics of the original forage [3].

#### **4.2. Characteristics of silages**

Silage temperatures (in the range between 18 and 21°C) were adequate, Borreani and Tabacco [20] report that in well preserved silage the temperature should be close to the ambient temperature.

Silage pH is one of the main factors that influences the degree of proteolysis [21] in silages; the results attained (**Table 3**) were not conclusive since treatments effects differed between phases and short-term weather variables are a feasible explanation for these differences. The pH values fluctuated between 4.6 and 4.9; analogously, in alfalfa silage with *L. buchneri* inoculant [22] detected a pH of 5.0. In phase two, the pH values of silage from forage harvested at 14:00 were lower, which would coincide with higher levels of MS and ASC contents, conditions that optimize LAB activity and explain the advantage of harvesting forage in the afternoon hours [19]. According to Tyrolová and Výborná [23] for forages with less than 20% DM, it is necessary to acidify the forage up to a minimum pH of 4.2 and for forages with 30% DM a pH of 4.45 is acceptable, which implies that average pH in silages of this experiment were somewhat high. Concurrently, Kung [24] states that pH values higher than 4.6 to 4.8 in legume silages may be due to ensiling at DM contents lower than 30%.

two classes were harvest time (Class 2 mostly harvested at 08:00) and, during the previous 6 h to sealing of silos, 72% lower evapotranspiration and 47% higher proportion of rain events. Class 3 comprised a low proportion of spoiled silage which faced heavy rainfall in the 6 h

Ensiling Alfalfa (*Medicago sativa* L.) and Orchard Grass (*Dactylis glomerata* L.) Forage Harvested…

http://dx.doi.org/10.5772/intechopen.81509

119

From the above, it follows that the harvest in the afternoon after consulting weather forecasts trying to ensure that there will not be rain events and that there will be conditions for high evapotranspiration are essential factors for the success of ensiling; these results concur with those of Coblentz and Muck [4]. If these conditions are met, wilting and inoculation can con-

Harvesting alfalfa and orchard grass forage at 14:00 was advantageous since it led to silage with higher contents of dry matter and alcohol soluble carbohydrates and lower content of

Absence or rain and high evapotranspiration favored the achievement of positive effects of harvesting in afternoon hours. The effect of wilting and inoculation were bound to rainfall and evapotranspiration conditions during ensiling; under good weather conditions of wilting and inoculation contributed to improve the silage quality in terms of high dry matter content,

The authors are grateful to CONACYT for the M Sc Studies grant of the second author.

\*, Renato González-Ortiz1

1 Animal Science Graduate Program, Autonomous University Chapingo, Texcoco, Mexico

and Pedro Topete-Pelayo3

2 CIMMYT. International Maize and Wheat Improvement Center, El Batán, Mexico 3 Animal Science Department, Autonomous University Chapingo, Texcoco, Mexico

, Luis A. Miranda-Romero1

,

prior to the closure of silos.

**5. Conclusions**

neutral detergent fiber.

**Acknowledgements**

**Conflict of interest**

**Author details**

Ricardo D. Améndola-Massiotti1

Juan A. Burgueño-Ferreira<sup>2</sup>

tribute to improve the silage quality.

low pH and better aerobic stability.

Authors declare they have no conflict of interest.

\*Address all correspondence to: r\_amendola@yahoo.com

The NH3-N content is an important indicator, since it shows the amount of protein that has been degraded to ammonia. High NH3 -N contents such as found in this experiment (except for silages from forage harvested at 14:00 and with inoculant added) result from extremely high breakdown of protein, which is frequent in silages with DM contents lower than 30% [24].

The concentration of ASC in the original forage was on average 4.1% and was reduced in all silages in increasing proportion as the initial content was higher (P < 0.01), indicating that they were efficiently used by LAB [21]. If there had been a higher concentration of ASC in the original forage, the silage pH would have been even lower; therefore, according to the results of the review by Yitbarek and Tamir [25], the addition of a source of highly fermentable carbohydrates such as molasses would be a suitable alternative.

In the three phases the content of NDF in silage decreased as the wilting time increased, an effect that coincides with the results of Hashemzadeh-Cigari et al. [26] who found that wilting alfalfa before ensiling decreased the NDF content in silage.

The in vitro disappearance of DM presented average values of 59, 50 and 52% in phases one, two and three respectively and are lower than the values reported by Rizk et al. [27] who reported an average of 65%, these differences can possibly be attributed to the fact that in the present study the ensiled forage had low DM content.

#### *4.2.1. Aerobic stability of silages*

Forage silages harvested at 08:00 h and inoculated were less stable than those ensiled without inoculants; on the other hand, in forage harvested at 14:00, inoculated silages were more stable. Similarly inoculants were more effective in improving different silage attributes when applied to wilted forage than to fresh forage [26]. Improvement of the aerobic stability characteristics of silages, as in the present study, might be expected with the use of heterofermentative LAB inoculants or mixed heterofermentative and homofermentative LAB [7].

## **4.3. Results of principal component analysis**

In Class 1 the best quality silages were found, with lower pH, lower aerobic deterioration and higher DM content, the silages of that class were, in a very high proportion, harvested at 14:00 with very low proportion of rain events, relatively high evapotranspiration, mostly subjected to wilting (75% versus 66% expected), with highest DM% of original forage, and as in the other two classes no clear effect of inoculant addition. The highest proportion of silages was identified in Class 2, of lower quality than Class 1. The main differences between these two classes were harvest time (Class 2 mostly harvested at 08:00) and, during the previous 6 h to sealing of silos, 72% lower evapotranspiration and 47% higher proportion of rain events. Class 3 comprised a low proportion of spoiled silage which faced heavy rainfall in the 6 h prior to the closure of silos.

From the above, it follows that the harvest in the afternoon after consulting weather forecasts trying to ensure that there will not be rain events and that there will be conditions for high evapotranspiration are essential factors for the success of ensiling; these results concur with those of Coblentz and Muck [4]. If these conditions are met, wilting and inoculation can contribute to improve the silage quality.
