INTRODUCTION
Latin American cattle rearing is one of the main productive activities of the region. Its economic importance lies on the use of great land extensions in agroecosystems, which contributes to a total supply of food and it is the main source of employment and incomes, especially in small and medium farms with double purpose (Rodríguez et al. 2011).
Therefore, it is important the introduction of new genus of grasses, which may adapt to different edaphoclimatic conditions, in order to develop more sustainable and productive systems in tropical areas. The forage species of Cenchrus and Lolium genus may be a solution for the previously mentioned problem (Posada et al. 2013).
Cenchrus clandestinum is characterized by being highly productive during rainy season. However, its production decreases during dry season. Understanding its performance and determining the adequate moment for harvesting, whether it is green or preserved, is essential for offering an excellent quality and quantity of this forage base to animals (Carulla and Ortega 2016 and Arango et al. 2017). On the other hand, Lolium perenne belongs to a genus of species that can be cultivated from the sea level, up to 4200 m o.s.l., which favors a high demand as animal food in different tropical areas (Bezada et al., 2017).
In general, these species may have a fast growth and maturation. Due to this feature, its nutritional quality also changes rapidly because, with age, they experience sensitive and gradual changes in their chemical composition (Valenciaga et al. 2009 and Álvarez et al. 2017).
Therefore, the objective of this study was to determine the quality of Cenchrus clandestinum and Lolium perenne forages in the form of hay at different regrowth ages.
MATERIALS AND METHODS
Localization of the study area. The research was performed at the Facultad de Ciencias Pecuarias of the Escuela Superior Politécnica from Chimborazo, Ecuador. It is located at the Panamericana Sur, km 1.5 with an altitude of 2,780 m.o.s.l., at 1o 38’ S and 78o38‘W. Mean temperature was 14ºC, with a humidity of 67%, and precipitations reached 561mm. Soil characteristics are shown in table 1.
Experimental procedure. An amount of 30 crossbred (Rambouillet x Criollo) male sheep, 14 months old, and 25 kg of average weight, were used. These animals were placed in metabolism cages of exclusion for digestibility tests, with two weeks for adapting to the food they were going to receive. They were also treated against ectoparasites and endoparasites before starting the test.
Cenchrus clandestinum and Lolium perenne forages were used in hay shape (FAO 2018). For the preparation of the material, these species were cut at five centimeters high at 30, 40 and 50 days (Cenchrus clandestinum) and 40, 50 and 60 days (Lolium perenne), without irrigation and fertilization.
Hay was supplied to animals at 8:00 and 16:00 h daily, with water ad libitum without the inclusion of other feeding source.
Treatment and experimental design. A completely at random design was used, with three treatments and five repetitions, for each of the species that were separately evaluated. For Cenchrus clandestinum, ages evaluated 30, 40 and 50 days of age, and for Lolium perenne at 40, 50 y 60 days. Each animal was considered as an experimental unit and a replication at the same time, within each treatment.
Hay preparation. For producing hay, an area with three years of establishment of Cenchrus clandestinum and Lolium perenne was used. A uniformity cut was performed at 5 cm from the soil, for, afterwards, cultivating these species at the age of 30, 45 and 50 days of regrowth for Cenchrus and 40, 50 and 60 days for Lolium.
For hay production, forage was manually harvested and the cut was carried out during the morning. Forage was dried under the sun for 8 days over a cement platform and a turning of material was performed every 48 hours. Later, it was homogenized depending on the studied age, and 200 g of each were taken for further lab analysis.
Evaluated variables. Dry and organic matter, ash, crude protein (CP), and crude fiber (CF) were determined according to AOAC (2016). Likewise, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were determined by Van Soest and Wine (1967).
Fecal feces analysis. Feces recollection was performed during afternoon hours, and they werer taken to an air circulation oven for their dying at 65°C (AOAC 2016). Knowing the previously established chemical composition, dry matter digestibility (DMD) and organic matter digestibility (OMD) were determined, as well as crude protein digestibility (CPD) and crude fiber digestibility (CFD), according to Tobal (2017).
Facilities were maintained in good physical and hygienic conditions for avoiding collateral variations due to the effects of external factors.
Statistical analysis. A one-way analysis of variance and mean comparisons were performed. Bartlett (1937) tests were used for verifying homogeneity of variances and for determining Kolmogorov-Smirnov data normal distribution according to Massey (1951). Means were compared regarding Duncan (1955) test.
RESULTS
Results of chemical composition of Cenchrus hay (table 2) showed high values of DM, which is a component that guarantees a good haymaking. On the other hand, there are high contents of CP, with the best value at day 30, with significant differences among treatments. Neutral detergent fiber showed values superior to 34%, and they increased with the increase of the age of hayed plant material, showing significant differences among treatments. For acid detergent fiber, the highest value appeared at 50 days old, and it showed differences among the evaluated treatments. In the case of lignin, values increased with age of the hayed material, although it was not higher than 2.3%. There were differences among the evaluated treatments.
Variables % | Ages (days) | SE± | P | ||
---|---|---|---|---|---|
30 | 40 | 50 | |||
DM | 90.81a | 91.11a | 93.98b | 1.36 | 0.001 |
OM | 92.96a | 91.40b | 90.40c | 0.78 | 0.002 |
Ashes | 9.60a | 8.60b | 7.04c | 0.69 | 0.01 |
CP | 14.95a | 13.48b | 12.15c | 1.04 | 0.001 |
CF | 34.84a | 35.46b | 37.22c | 1.21 | 0.003 |
NDF | 34.40a | 35.90b | 37.60c | 1.16 | 0.002 |
ADF | 26.30a | 28.80b | 29.70c | 0.98 | 0.01 |
ADL | 1.90a | 2.10b | 2.30c | 0.09 | 0.002 |
Different letters in the same line differ at P≤0.05
Lolium perenne showed high contents of DM (table 3), which demonstrated a good haymaking of the evaluated material. CP reached high values, which were higher than 15%, guaranteeing a good quality food. The studied treatments showed significant differences among them for this indicator. In the case of CF and NDF, there were differences among treatments, observing an increase of these indicators with the increase of age of the hayed plant. The best results for these two variables appeared at 30 days old. In the specific case of ADF, the best value obtained in the first treatment, with significant differences among them (table 3). The ADL content in treatments with 40 and 50 days showed no differences among them, which was similar between 50 and 60 days. However, it is necessary to highlight that the lowest age was different from the highest age. In all the study, ADL increased with the age of the hayed material.
Variables % | Ages (days) | SE± | P | ||
---|---|---|---|---|---|
40 | 50 | 60 | |||
DM | 83.47a | 85.45b | 87.23c | 1.84 | 0.001 |
OM | 92.15a | 89.81b | 88.47b | 2.05 | 0.002 |
Ashes | 11.53a | 10.19b | 7.12c | 0.85 | 0.02 |
CP | 18.33a | 18.17a | 16.34b | 1.06 | 0.001 |
CF | 27.47a | 30.64b | 32.09c | 1.38 | 0.01 |
NDF | 61.20a | 62.60b | 63.70c | 1.16 | 0.003 |
ADF | 50.80a | 51.90b | 52.10b | 0.95 | 0.001 |
ADL | 4.10a | 4.20ab | 4.30b | 0.09 | 0.001 |
Different letters in the same line differ at P≤0.05
In the evaluation, it was evident that there were high percentages of dry and organic matter digestibility, which guarantees a good quality food to be hayified (table 4). In these two evaluated variables, there were significant differences among the studied treatments. For crude protein digestibility, the best result appeared at 30 days of age, with significant differences among treatments. Crude fiber digestibility showed the highest value for the first of treatment days, with significant differences among them.
Variables | Ages (days) | SE± | P | ||
---|---|---|---|---|---|
30 días | 40 | 50 | |||
DMD | 81.71a | 74.02b | 65.13c | 2.14 | 0.001 |
OMD | 82.68a | 75.39b | 68.54c | 3.24 | 0.02 |
CPD | 89.27a | 82.17bc | 71.16c | 2.45 | 0.01 |
CFD | 81.08a | 71.64b | 63.18c | 3.52 | 0.01 |
Different letters in the same line differ at P≤0.05
For Lolium perenne, DMD had no significant differences between the first two studied ages, but there were differences with the third. Something similar happened with organic matter digestibility. In the case of CPD and CFD, the best results appeared in the first treatment, showing differences with the other two evaluated treatments. For these two variables, digestibility decreased with the increase of age of the hayed material (table 5).
DISCUSSION
Grass quality is affected with the increase of age, mainly with the decrease of protein and energy, which is a limitant for cattle rearing systems in tropical areas (Álvarez et al. 2016). However, haymaking process is a method that allows to preserve forage with adequate chemical composition and quality for periods of low yield.
This research demonstrated that Cenchrus clandestinum, properly preserved in hay shape, may constitute a food option for cattle during periods of low forage availability due to its high percentage of dry matter, superior to 90%, and crude protein over 12, at the ages it was preserved. These results are inferior to those reported by Escobar (2018), who obtained values between 18-19% of crude protein at 30 and 60 days of regrowth. This author states that the quality of this plant and its preservation forms is affected by the age of plant material, with a significant influence on the environment in which it develops (Ramírez et al. 2015, and Correa et al. 2018).
However, it is known that, with low temperatures, grasses remain with good quality for more time (Herrero et al. 2000 and Escobar 2018). This previous statement justifies this research and opens a wide range of studies in Riobamba region, where temperatures oscillate depending on altitude, which generated morphological changes in this species, influencing on the quality of grass and its preserved forms (Arango et al. 2017).
In the specific case of Lolium perenne, DM and CP reached values superior to 83 and 16%, respectively, guaranteeing a good quality of this species in the haymaking process, with differences among all treatments. Literature results report similar values to those of this research (Castro et al. 2017). These authors informed between 89-90 % of DM and between 14-18% of CP, with different cut frequencies, pointing out that these values are obtained by a very close relation of processes occurring within the plant with the increase of age and interaction of climate elements, which justifies the results of this study.
Another study refers similar NDF values (66%), when evaluating Lolium perenne in experimental conditions with temperatures close to 18°C (Dimaté 2016). This author showed that these high fiber contents were favored by climate conditions of this area, which confirmed reports of Escobar (2018), referring that forages developed in places with lower temperatures, took more time to diminish their quality because they had a slower growth, similar to what happened in this research.
For both species, digestibility of dry matter and organic matter reached values superior to 66% and sometimes superior to 80%, which is very important for this research, especially when constant changes of structure and chemical composition are stimulated by the interaction of age with climate elements, according to Ledea et al. (2018), limiting their use by ruminal microflora. Ruiz and De-Arriba (1987) referred that concentration of organic matter in the cell wall (35-80%) is only degraded between 65-67% of the established form. These values are inferior to those obtained, stimulated by differences in climate conditions.
On the other hand, CP digestibility values in both species were superior to 70%, which is an element that guarantees a good quality of hay at the different regrowth ages evaluated in both species under study, especially if regrowth age stimulates the development of complex relations and interrelations established in the cell wall (Ledea et al. 2018), limiting its degradation because the animal has few pluri-enzymatic microorganisms in relation to the biota within the rumen (Galindo et al. 2014).
Several authors refer that, with the increase of regrowth age, structural carbohydrates prevail, along with the reduction of microbial access to the organic part of the cell lumen and cell wall. Therefore, organization of constituents of cell wall predisposes the access of microorganisms and enzymatic action on specific substrata, which is shown on degradability of different fractions (Fortes 2014, Pedraza 2014, and Caro and Dihigo 2015). However, fiber digestibility values obtained in this study, for both species, surpassed 60%.
Considering the previous criteria, the results of this research are vital and ratify the fact that at higher altitudes, quality of plants and its preserved forms has a slower decrease (Herrero et al. 2015, Escobar 2018).
Forages of Cenchrus clandestinum and Loliun perenne, at the evaluated ages, have an adequate quality to be preserved as hay under the climate conditions described in this study.
Further studies are suggested to evaluate other quality indicators at different latitudes in the region under study.