Ensiling characteristics and milk producing capacity of browse/maize forage mixtures

H Kato, F B Bareeba¹, C Ebong² and E N Sabiiti³

Department of Agriculture, Kyambogo University, P.O. Box 1, Kampala, Uganda
¹Department of Animal Science, Makerere University, P.O. Box 7062, Kampala, Uganda
fbareeba@agric.mak.ac.ug
²Namulonge Agricultural and Animal Production Research Institute, P.O. Box 7084, Kampala Uganda.
³Department of Crop Science, Makerere University, P.O. Box 7062, Kampala, Uganda
 

Abstract

An experiment was carried out to evaluate the ensiling characteristics and milk producing capacity of maize forage ensiled with Calliandra, Gliricidia and Leucaena foliage. The browse/maize silages made in pit silos and contained 20% browse (DM basis); the control silage was maize forage ensiled at milk stage. Molasses was added to all the silages at the rate of 5% (fresh weight) while urea was added to the maize forage alone at ensiling at 0.5% ( fresh weight) to raise the crude protein content to a comparable level as that in the browse/maize silages. The silages were fed to four lactating crossbred cattle (Friesian x indigenous cattle) supplemented with maize bran in a 4x4 Latin square design.

The silages fermented well with higher (P<0.05) lactic acid content in the browse/maize silages compared to maize silage. Silage DM intake and total DM intake were higher (P > 0.05) for Calliandra/maize silage which had correspondingly higher (P > 0.05) DM content. Dry matter digestibility was higher (P < 0.05) for maize silage but similar (P>0.05) for the other silages. Crude protein digestibility was similar (P>0.05) for Gliricidia/maize, Leucaena/maize and maize silages, but lower (P < 0.05) for Calliandra/maize silage. Milk yield was similar for Gliricidia/maize and Leucaena/maize silages (6.4 and 6.5 kg/day respectively), but higher (P < 0.05) than for Calliandra/maize silage (5.7 kg/day) and was least (P < 0.05) for the control maize silage (5.2 kg/day).

The results demonstrated the advantage of ensiling maize forage with the browses in terms of DM intake and milk yield.

Key words: browse/maize silages, digestibility, ensiling, milk producing capacity

Introduction

To optimize the utilization of low quality forages, and maintain adequate animal production, it is necessary to enhance feed intake and digestion through the provisions of supplemental nutrients (Mugerwa 2001). Generally, providing supplements with adequate crude protein (CP) to ruminants has promoted dry matter intake (DMI), rumen degradation, and nutrient flow to the small intestine and culminated in higher animal performance (Muinga et al 1995; Mpairwe et al 2003). Improvements in voluntary intake of low quality forages as a result of supplementation are frequently associated with increases in the rate of passage and forage digestion (Köster et al 1996). Browses have been fed to cattle as a source of supplemental protein (Preston and Leng 1987). In Uganda, Calliandra calothyrsus, Gliricidia sepium and Leucaena Leucocephala have been identified and recommended as the most suitable species (Sabiiti 2001). However, they contain antinutritional factors (Bareeba and Aluma 2000), which could be ameliorated by ensiling. The objective of the study was to investigate the ensiling characteristics and milk producing ability of ensiled browse/maize fodder mixtures.

Materials and methods

Calliandra, Gliricidia and Leucaena foliage (leaf and petiole, and edible soft stems) were harvested three months after pruning. They were mixed with maize forage (25% DM) at 20% (DM basis) and ensiled in trench silos. Urea was added to maize forage alone at 0.5% (fresh weight) at ensiling to raise the CP content to comparable levels with those of browse maize silage. This acted as a control. Molasses (5% fresh weight) was added to all the ensiled materials to aid fermentation.

A 4x4 Latin square design was used for a feeding trial with four lactating crossbred cows (Friesian x indigenous cattle) in early lactation. There were four feeding periods of 28 days each in which the adjustment period was two weeks and data were collected for two weeks. The animals were confined in stalls and fed from troughs. Fresh silage was offered ad libitum twice a day at 8 and 14 hrs. In addition, each animal received 3 kg of maize bran offered in two equal halves during milking. The animals were weighed for three consecutive days at the beginning of the experiment and at the end of each feeding period using a portable electronic weighbridge.

During the second and third week of each period, the animals were dosed with 30g of chromic oxide daily in two equal halves of 15g for the a.m. and p.m. feeding. Grab faecal samples were taken daily in the morning and afternoon during the third week and were composited.

Milk yield was recorded daily for the morning and afternoon milking during the last two weeks of each period. The am and pm milk samples were obtained after the milk was thoroughly mixed. The samples were strained through a clean piece of cloth and preserved with 3 to 4 drops of 10% potassium dichromate. The am and pm samples were composited and mixed thoroughly to make the day's sample and were kept in a cold room until analysed.

The DM of the silages and faeces was determined by drying samples to constant weight at 60^oC in a forced-air oven. Water extracts of silages were prepared by shaking 100 g of the silages in 800 ml of water for two hours on a mechanical shaker. After shaking, water was added to make 1 L. The extracts were filtered through two layers of cheesecloth. Lactic, butyric and acetic acids were determined by fractional distillation and titration using standard procedures in the Department of Animal Science, Makerere University. The pH of the water extracts was also determined. Determination of NH3-N was done by distillation into boric acid and titration. DM losses were determined as the difference between the total DM of the ensiled materials in buried bags before and after ensiling.

Samples of feed and faecal were analysed for crude protein (CP), calcium (Ca) and phosphorus (P) according to AOAC (1990) procedures. Non-protein nitrogen (NPN) was determined by the trichloroacetic acid method (Gaines 1977). Neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) were determined as described by Van Soest and Robertson (1985). Milk samples were analysed for total protein by the Kjeldahl method; butterfat by the Gerber method; total solids by evaporation and total-solids-not fat by difference between butterfat and total solids.

Estimation of energy intake and energy and protein requirements of the cows was done according to MAFF (1987) guidelines.

The data obtained were subjected to analysis of variance using the General Linear Model (GLM) procedures of SAS (1999). Where significant differences were obtained, means were compared using SE at probability level of 5%.

Results and discussion

Fermentation characteristics and chemical composition of the silages

Calliandra/maize silage had the best fermentation on account of its higher lactic acid and lower pH levels (Table 1). However, fermentation of Gliricidia/maize, and Leucaena/maize silages was also good as all the browse silages had lactic acid content higher than 4.5% and low pH ranging between 3.62 and 3.88 (Mahana 1998). Maize silage on the other hand, had lower lactic acid content, a higher pH and lower NH₃-N content.

Therefore, while addition of molasses to the silages could have improved the fermentation of the browse/maize silages, addition of urea to the maize silage could have restricted proteolysis hence, the lower levels of NH₃-N in maize silage (Bareeba 1979; Mahana 1998). The lower levels of NH₃-N could also be an indication of restricted fermentation, hence the lower lactic acid level and higher pH of the maize silage (Mahana 1998). Also urea could have had a buffering action during fermentation as well as exerting a protein sparing effect on the natural protein in the maize silage (Bareeba 1979).

The browse/maize silages had higher CP content than maize silage (Table 2) in spite of addition of urea. However, maize silage had higher soluble N (NPN) content, indicating that much of the NH₃-N combined with the organic acids and formed ammonium salts. The higher content of soluble NPN would make maize silage more degradable in the rumen (Bareeba 1979).

Silage dry matter consumption and digestibility

Silage DMI was higher for Calliandra/maize and Leucaena/ maize silages than for Gliricidia/maize or maize silage (Table 3). The higher (P<0.05) DM consumption of Calliandra/maize silage compared to the rest of the silages could have been due to the initial higher DM and low butyric acid of the silage (Cushnahan and Gordon 1995). The higher level of butyric acid and NPN in Leucaena/maize silage (Table 1) could have resulted into low DM intake (Cushnahan and Gordon 1995). Gliricidia/maize silage had a relatively higher level of butyric acid, which together with the low DM content and higher level of NH₃-N (Table 1) could have contributed to its lower DM intake (Mahana 1998).

Maize silage had less acidity and NH₃-N levels (Table 1), which should have increased its intake. However, maize silage had a high level of NPN (Table 2) perhaps as a result of urea addition, which could have limited its DMI (Mahana 1998).

There were no significant differences (P>0.05) in the digestibility of DM, between the silages (Table 4). The digestibility of CP was lower (P<0.05) for Calliandra/maize silage probably due to presence of tannins. While there were no significant differences in the digestibility of NDF between the silages, the digestibility of ADF was higher (P<0.05) with maize silage. The low lactic acid level, higher pH and lower NH₃-N level (Table 1) in spite of urea addition, meant that fermentation in maize silage was buffered (Bareeba 1979) and its fermentation was therefore, limited (Table 1). This could have left part of the more soluble forms of cellulose unfermented, which was then degraded in the rumen giving rise to the higher digestibility of ADF observed with maize silage. Metabolisable energy intake was similar among the treatments and met the animal's requirements. However CP intake was far below the requirements, which together with the early lactation stage led to loss in weight of the animals.

Milk yield and composition

Milk and FCM yields were higher (P<0.05) with Gliricidia/maize and Leucaena/maize silages (Table 5), which could have been as a result of the relatively higher intake of digestible CP of the two silages (Table 4). Also, although CP intake with all the silages could not meet the protein requirements for maintenance and milk production of the cows (Table 4), the ratio of digestible CP intake to CP requirement was higher with Gliricidia/maize and Leucaena/maize silages (Table 4), which could have resulted in higher milk yield with the two silages. Although Calliandra/maize silage supported higher (P<0.05) milk yield than the control maize silage (Table 5), feed efficiency of the silages for milk production (milk kg/kg of total DM intake) was similar between Calliandra/maize and maize silages (Table 5). Maasdorp et al (1999) found no beneficial effect of feeding Calliandra calothyrsus hay for milk production in lactating dairy cows.

Milk protein content was higher (P<0.05) with Calliandra/maize and maize silages (Table 5). Addition of urea to maize silage increased its soluble N content and could have been beneficial for increasing the milk protein content (Sanz Sampelayo et al 1999; Kalscheur et al 1999).

Milk butterfat content was similar among silages. However digestibility and intake of ADF were higher for maize silage (Table 4) and could have influenced the relatively higher butter fat content with maize silage (Table 5), as milk fat content is a reflection of dietary roughage intake (Sutton et al 1994). Solids-not-fat and total solids content was higher (P<0.05) with Calliandra/maize and maize silages. Butterfat and milk protein yields were higher with Gliricidia/maize and Leucaena/maize silages as a result of higher milk yield with the two silages (Table 5).

Conclusions

• Ensiling browses with maize forage at 20% (DM basis) did not affect fermentation and increased CP content of the resultant silage.

•  Browse/maize silages supported higher milk yield than maize silage alone even when maize silage was enriched with addition of urea.

• The results of this study indicate that ensiling Calliandra, Gliricidia and Leucaena browses with maize forage improved their utilisation for milk production in lactating cows and that Gliricidia and Leucaena browses were utilised better than Calliandra.

References

AOAC 1990 Official methods of analysis, 15^th Edition. AOAC Inc. Arlington, Virginia 22201 USA

Bareeba F B 1979 Use of Pro-sil-treated corn silage and Fababean silage in rations for lactating dairy cows. Ph D Thesis, University of Manitoba

Bareeba F B and Aluma J 2000 Chemical composition, phenolics and in vitro organic matter digestibility of some multipurpose tree species used for Agroforestry in Uganda. Uganda veterinary Journal, 6(1):89-92

Cushnahan A and Gordon F J 1995 The effects of grass preservation on intake apparent digestibility and rumen degradation characteristics. Animal Science 60: 429-438.

Gaines T P 1977 Determination of protein nitrogen in plants.  Journal of the AOAC, 60: 590.

Kalscheur K F, Vandersall J H, Erdman R A, Kohn R A and Russek-Cohen E 1999 Effects of dietary crude protein concentration and degradability on milk production responses of early, mid and late lactation dairy cows. Journal of Dairy Science 82: 545-554. http://jds.fass.org/cgi/reprint/82/3/545

Koster H H, Cochran R C, Titgemeyer E C, Vanzak E S, Abdelgadir I and St Jean G 1996 Effect of increasing degradable intake protein on intake and digestion of low quality tall grass-Prairie forage by beef cows. Journal of Animal Science 74: 2473-2481. http://jas.fass.org/cgi/reprint/74/10/2473

Maasdorp B V, Muchenje V and Tetterton M 1999 Palatability and effect on dairy cow milk yield of dried fodder from the forage trees Acacia boliviana, Calliandra calothyrsus and Leucaena leucocephala. Animal Feed Science and Technology 77: 49 - 59

MAFF 1987 Energy allowances and feeding systems for ruminants. Ministry of Agriculture, Fisheries and Food, Department of Agriculture and Fisheries for Scotland. Reference Book 433. Her Majesty, Stationary Office, London

Mahana B 1998 Trouble-shooting silage problems. Crop management research and technology. Pioneer Hi-bred International Inc. USA.

Mpairwe D R, Sabiiti E N, Ummna N N, Tegegne A and Osuji P 2003 Integration of forage legumes with cereal crops. I. Effects of supplementation with graded levels of Lablab hay on voluntary intake, digestibility, milk yield and milk composition of cross bred cows fed maize-Lablab stover or oats vetch hay ad libitum. Livestock Production Science 79: 193-212.

Muinga R W, Topps J H, Rooke J A and Thorpe W 1995 The effect of supplementation with Leucaena leucocephala and maize bran on voluntary food intake digestibility, liveweight gain and milk yield of Bos indicus x Bos Taurus diary cows and rumen fermentation in steers offered Pennisetum purpureum ad libitum in the semi-humid tropics. Animal Science 60: 13-23.

Mugerwa J S 2001 Animal feed resources. in Agriculture in Uganda. Volume IV Livestock and Fisheries IV. Editor: Mukiibi J K, NARO, pg. 196-236.

Sabiiti E N 2001 Pastures and range management. in Agriculture in Uganda. Volume IV Livestock and Fisheries. Editor: Mukiibi J K, NARO, 4: 237-297.

SAS Institute Inc. 1999 Statistical Analysis Systems Institute Inc., SAS/STAT User's Guide, Cary, NC, USA 84 699.

Sanz Sampelayo M R, Perez M L, Gil Exremera F, Boza J J and Boza J 1999 Use of different dietary protein sources for lactating goats: Milk production and composition as functions of protein degradability and amino acid composition. Journal of Dairy Science 82: 555-565. http://jds.fass.org/cgi/reprint/82/3/555

Sutton J D, Aston K, Beever D E and Fisher W J 1994 Milk production from grass silage diets: the relative importance of the amounts of energy and crude protein in the concentrates. Animal Production 59: 327-334.

Topps J H 1992  Potential, composition and use of legume shrubs and trees as fodder for livestock in the tropics. Journal Agricultural . Science. Cambridge, 192 (118)

Van Soest P J and Robertson J B 1985 Analysis of forage and fibrous foods. A laboratory manual for Animal Science 613. Cornell University, Ithaca. New York, USA