Investigation on change of forage quality at harvesting, during hay making and storage of hay harvested at different growth stages in the Adamawa plateau of Cameroon

M B Enoh, C Kijora*, K J Peters*, V N Tanya, D Fonkem and J Mbanya

Wakwa Institute of Agricultural Research for Development, P.O Box 65 Ngaoundere, Cameroon
^*Institute of Animal Sciences, Humboldt-University Berlin, 10115 Berlin, Germany
claudia.kijora@rz.hu-berlin.de

Abstract

An experiment was carried out to assess the dry matter and nutrient loss during hay making and storage of hay from native (dominated by Hyparrhenia species) and cultivated (Brachiaria ruziziensis Germain and Evrard) pasture at the Wakwa Research Centre of Cameroon in the subtropical Africa. The dry matter and quality losses were assessed for three stages of the pasture regrowth (8, 0 and 12 weeks) at harvesting, at baling and at storage of the hay for different length of weeks (0, 12 and 20 weeks). 

There were significant differences in yield and quality between harvested pasture and dried hay, which were affected also by pasture type and regrowth length. The DM yield was decreased during the hay making process by 12%, which indicates the good conditions for hay making in this region of Cameroon during the experimental period. Storage of hay in a shed did not remarkable change the quality except the protein content. The quality of Brachiaria was higher than the native pasture throughout the experimental period of storage, however the quality loss of Brachiaria at hay cutting compared to at harvesting was high. The loss of quality evaluated by in vitro and in situ methods (Nylon bag degradability and enzyme cellulase degradability) showed inconsistent results.

Keywords: Brachiaria ruziziensis, hay yield loss, native pastures, storage of hay

Introduction

One of the most common methods of forage conservation is hay making. The primary goal of forage conservation is to maintain its quantity and quality with minimal loss during harvesting and storage (Rotz and Muck 1994). Loss is influenced by the type of forage species, kind of hay making equipments, storage facilities, and the weather conditions at harvesting, drying and storing. The energy loss from forage during hay making can vary in a wide range between 5 and 100% (Rotz and Muck 1994). Under good drying conditions dry matter losses are between 15 and 18% (Rotz and Abrams 1988), and with rain damage, up to 30 % DM. In general, average hay making processes lead to a 24 to 28% loss in forage dry matter yield, most of which is during harvest and about 5% loss during storage (Buckmaster et al 1989 a,b)

The objective of this study was to assess the level of nutrient losses of different pasture species during the process of hay making and storage over a period of 20 weeks under the subtropical environmental condition at Adamawa, Cameroon

Material and methods

This investigation was carried out at the Wakwa research centre (Institute of Agricultural Research for Development, Wakwa) of Cameroon. Wakwa is located at an altitude of 1200 m above sea level. The plateau has a mild highland subtropical climate (mean annual temperature of 22 ˚C and a relative humidity of 40 - 60 %), with a precipitation of 1600 - 1700 mm per annum, falling mainly between April and October. The vegetation of the study area is sudano-guinean savanna.

The experiment was carried out in a randomised complet blockdesign with 6 replications involving two types of pastures (cultivated- Brachiaria ruziziensis and native pasture). After being grazed at a fixed stocking rate (1.5 TLU/ha) the pastures were maintained to three regrowth length treatments (8, 10, 12 weeks) by cutting the different paddocks at intervals of two weeks. All experimental pastures were cut for hay making at the beginning of dry season using a tractor driven grass cutter. The harvested herbage was allowed for sun drying on the field for four days and immediately made to round bales of about 150 kg each. While drying the herbage was turned and made into windrows after the second day. The bales were stored in a shed with straight-through ventilation and were sampled with a coring device at entry into storage (0 days storage period), after 12 and 20 weeks of storage.

Samples for laboratory analysis were dried at 65ºC for 48h and for DM determination at 105ºC over 24h. Quality measurements consisted of proximate and detergent analysis (Naumann and Bassler 1997), the nylon bag method (Osuji et al 1993) and the pepsin cellulase- solubility method (De Boever et al 1986; Naumann and Bassler 1997).

Data were analysed using the general linear models (GLM) procedure of SAS (1991). Type III sums of squares were used to separate treatment means.

Results and discussion

The average dry matter (DM) percentage of hay was 88.9 ± 0.24 % with a significant increase during storage from 88.0, 88,9 and 89.9 % at week 0, 12 and 20, respectively, which however, demonstrated a rather satisfactory storability. A comparison between estimated total dry matter at harvesting and hay making for the different growing lengths of the two pasture types are indicated in Figure 1.

Figure 1. DM yield at harvesting and hay baling of native and Brachiaria pastures
harvested at different lengths of growing period

DM yield at harvesting and hay baling of native and Brachiaria pastures harvested at different lengths of growing periodThe average dry matter yield loss from Brachiaria was higher than native pasture (15% vs. 9%) and the total dry matter loss increased as the growing period increased. The yield loss during the hay making process is a result of three main affecting factors, weather conditions, mechanical influences and the respiration. Owing to the very good weather condition at harvesting time (no rainfall and a relative humidity of 62%) the drying process was very fast. After 4 days (the time of baling the hay) the average dry matter content was 88.9%. The total loss in DM yield of 12% is rather low. An obligatory respiratory loss between 5 and 6% is reported by Henning and Wheaton (1993).

At the longer growing period of 12 weeks the dry matter yield obtained from hay at baling was 18% lower than the yield at harvesting, while it was only 4% at 8 weeks growing period. The higher yield loss of Brachiaria especially at the later stage of maturity at cutting (12 weeks re-growth) (Figure 1) seems to be mainly a result of mechanical influences. According to Savoie (1988) and Shinners et al (1991) the maturity of grass from late vegetative to full bloom stage can double the dry matter loss. This is due mainly to the lower moisture content at harvesting and the weakened attachment of leaves. In this experiment the DM loss was increased by four folds when the regrowth harvesting time prolonged from 8 to 12 weeks. This is a higher dry matter loss than described in the literature. This may be a result of the low moisture content for the 12 week regrowth (dry matter content at baling was 90.3%), which made the hay too brittle. A minimum moisture content of hay at baling is not well described in the literature, but dry matter below 20-22% is required for low yield loss (Pyatt and Berger 2003; Henning and Wheaton 1993). Rotz (2003) pointed out that a mechanical manipulation like raking or tedding late at the drying process leads to DM losses of more than 10%. The tedding of hay after two days drying in this experiment could be the reason for the high DM yield loss in hay at the late maturity stage.

The nutrient content of the pasture at harvesting and the hay is indicated in Table 1. All the measured nutrients of the pasture at harvesting or hay showed a significant variation.

The crude protein and NFE contents decreased while CF, NDF, ADF and ADL increased in the process of hay making. On average the fibre content of the hay was higher by 10% than the pasture without remarkable differences between the several analysed fibre fractions. Brachiaria at harvesting had a significantly higher crude protein content and lower CF and ADF value than native pasture. However, the quality lost during the hay making process was higher for the Brachiaria than the native pasture (Table 1). The crude protein content of Brachiaria was decreased by 25 %, compared with 10% for the native pasture; thus the advantage of Brachiaria hay over native hay at baling was reduced to 4%. Brachiaria hay showed a higher increment in the fibre content than the native hay especially for the ADL and crude fibre fractions.

The main factor for the loss differences between the two pasture types could be also mechanical influences, caused by the higher leaf to stem ratio in Brachiaria. The chemical analysis of both pasture types underlines this assumption, because the quality loss from Brachiaria was higher than the native hay. The higher crude protein loss from Brachiaria (24%) relative to the native hay (19%) seems due to the high proportion of leaves lost in Brachiaria. During the 20 weeks storage of hay the change in quality was negligible, except for protein content, which declined from 43.8g/kg DM at baling time to 40.3 g/kg DM at week 20. This indicates that storing hay in a shed is an appropriate way under Adamawa (subtropical) and similar areas. The slight reduction of the crude protein content could be related to a continuous slow dissipation of NPN formed by respiration associated with the drying process. As described by Brady (1960), Melvin and Simpson (1963) and Carpintero et al (1979), the protein at hay making breaks down at a first step to simpler non protein nitrogen compounds. The hemicellulose content (NDF-ADF) is constant during the experimental period. The cellulose content (ADF-ADL), however, increased from pasture at harvesting (330 g/kg DM ) to the longest period tested, 20 weeks (370 g/kg DM). This indicates that the hemicellulose loss was related to the DM loss while the cellulose content (mainly in stems) was not changed.

The relative dry matter and nutrient yields of the two pasture types at harvesting and of hay at baling are illustrated in Figure 2. It clearly indicates the lower yield and quality advantage of Brachiaria over the native pasture when they were made hay.

Figure 2. Relative dry matter and nutrient yield of pasture at harvesting
and hay at baling - average values of pasture and hay is zero

The change of water solubility, in vitro and in situ parameters measured during the experiment is shown in Table 2.

The nylon bag degradability of hay at baling was 5% lower than the pasture at harvesting and the cellulase solubility of organic matter (ELOS) was 18% lower. The greatest difference was measured in the water soluble part, which decreased more than 20%. The storage time has only a small influence on nylon bag degradability and pepsin - cellulase solubility.

The large discrepancy between these two methods underlines the problems of using standardised methods developed and used for intensively managed temperate (C3) grasses for quality determination of tropical (C4) grasses.

Conclusions

• This study has shown that hay making of native and Brachiaria pastures is an appropriate management method of forage conservation in the Adamawa region of Cameroon and other similar subtropical areas.

• Stage of maturity, overdrying especially for leafy pastures and time of baling contributed to the major loss of dry matter and nutrients during the process of hay making. A careful follow-up of the optimum harvesting stage, length of drying period and time of baling is of paramount importance.

• Despite high dry matter forage productivity of the cultivated Brachiaria relative to the native pasture, the dry matter and nutrient loss from Brachiaria was very high, suggesting the need of intensive care during hay making of highly productive cultivated pastures like Brachiaria.

Acknowledgements

The authors gratefully acknowledge the financial support of the Deutscher Akademischer Austausch Dienst (DAAD) for its financial support. Our thanks are also due to the former Director of the Institute for Animal and Veterinary Research (IRZV) in Yaounde, Dr. Banser and to the head and staff of the Wakwa research centre (IRAD Wakwa). Thanks are also to the Institute of Animal sciences of the Humboldt University of Berlin, Germany, for making available their laboratory facilities.

References

Brady C J 1960 Redistribution of nitrogen in grass and leguminous fodder plants during wilting and ensilage. Journal of the Science of Food and Agriculture 11, 276-284.

Buckmaster D R, Rotz C A and Mertens D R 1989a. A model of alfalfa storage. Transactions Association of Agricultural Engineers (ASAE), USA 32, 30-36.

Buckmaster D R, Rotz C A and Muck R E 1989b. A comprehensive model of forage changes in the silo. Transactions Association of Agricultural Engineers (ASAE), USA. 32: 1143-1152.

Carpintero C M, Henderson A R and McDonald P 1979. The effect of some pre-treatments on proteolysis during the ensiling of herbage. Grass and Forage Science 34, 311-315

De Boever J L, Cottyn B G, Buysse F X, Wainmann F W and Vanacker J M 1986 The use of an enzymatic technique to predict digestibility, metabolizable and net energy of compound feedstuffs. Animal Feed Science and Technology 14: 203 - 214.

Henning J C and Wheaton HN 1993 Making and storing quality hay. 301.2004 1-5 http://muextension.missouri.edu/explore/agguides/crops/g04575.htm

Melvin J F and Simpson B 1963 Chemical changes and respiratory drift during the drying of ryegrass. Journal of the science of food and agriculture 14: 228-234

Naumann C and Bassler R 1997 Die chemische Untersuchung von Futtermitteln. In: Methodenbuch, Band III, 3. Ergänzungen, 1993. VDLUFA Verlag, Darmstadt, Germany, pp.1-6.

Osuji P O, Nsahlai I V and Khalili H 1993 Feed Evaluation. ILCA Manual no.5. Addis Ababa, Ethiopia. 40pp.

Pyatt N A and Berger L L 2003 Storage and feeding losses of large round bales in Illini BeefNet- the online resource for the beef industrie  http://www.traill.uiuc.edu/beefnet/paperDisplay.cfm?Type=Both&ContentID=434

Rotz C A 2003 Effectiveness of equipment to speed hay drying in Symposium and joint meeting of professional nutrient applicators of Wisconsin forage council. p 1-5;  http://www.uwex.edu/ces/forage/wfc/proceedings2003/speedhaydrying.htm

Rotz C A and Abrams S M A 1988 Losses and quality changes during alfalfa as hay harvest and storage. Trans American Association of Agricultural Engeneering 31: 330-355.

Rotz C A and Muck R E 1994 Forage quality, evaluation and utilisation In: Forage quality. Evaluation and Utilization. (Editor: Fahey C Jr). University of Nebraska, Lincoln, USA. pp. 828 - 868.

SAS, 1991 Statistical Analytical Systems Institute. SAS/STAT user's guide release 6.03. Statistical analysis systems Institute, Inc., Cary, NC, USA.

Savoie P 1988 Hay tedding losses. Canadian agricultural Engineering 30: 39-42.

Shinners K J, Koegel R G and Straub R J 1991 Leaf loss and drying rate of alfalfa as affected by conditioning roll type. Applied Engineering in Agriculture 7: 46-49.