Nutritional potential of bamboo leaves for feeding dairy cattle in Madagascar

Methods In the Highlands of Madagascar, dairy farming is an important source of income for many farmers. It involves almost half of farmers in this region. Milk productivity is still low compared to the cow’s genetic potential. The main constraint is the lack of fodder, essentially during the dry season. Natural pastures and crop residues are the main source of feed for ruminants during this period. They are usually rich in fibre and devoid of most essential nutrients. Bamboo produces a high amount of green leaves throughout the year. Bamboo leaves can be an alternative fodder for dairy cattle in order to maintain the milk production during the feed period shortage. However, the use of bamboo leaves as fodder has not been investigated in Madagascar. Information on their nutritive value is still limited. The aim of the present study is to determine the nutritive value of local bamboo leaves and to assess the impact of their use on the milk productivity.


INTRODUCTION
To meet the increasing global food demand, it is necessary both to increase the productivity and to use available resources more efficiently.Family farmers constitute approximately 60 % of the global agricultural production (FAO 2016).Around 98 % of farms in the world are family farms that are heavily Feed shortage during the dry season in the highlands of Madagascar negatively impacts the dairy cattle productivity, as well as the farmers' income.Bamboo can produce a high quantity of biomass and could be an alternative way to increase the fodder supply for cattle.The present study aimed to assess the compositional information and the optimal rate of bamboo as fodder for dairy cattle.Leaf samples from nine bamboo species were collected to determine their chemical composition and nutritive value.A feeding experiment was also conducted using ten dairy cows, over ten weeks.Bamboo leaves were mixed with maize silage in five proportions: SIL0:BAM100, SIL25:BAM75, SIL50:BAM50, SIL75:BAM25 and SIL100:BAM0.The contents of dry matter, total ash and crude protein in the bamboo leaves were, respectively, 44.5-64.6 %, 6.68-18.5 % and 7.71-15.4%.In the feeding trial, the dry matter intake of bamboo leaves was 1.6-7.1 kg per day, with an average of 4.8 kg per day.The dry matter apparent digestibility of bamboo leaves was 37. 4-56.4 %.The milk production reached 13.6-14.4L per cow, per day, but there was no significant difference concerning the rate of bamboo leaves in the mixed diet (p > 0.05).The introduction of bamboo leaves into the ruminants diet did not affect their milk production.KEYWORDS: Fodder, in vivo digestibility, woody grass.

Special Supplement: Bamboo
Around half of the famers in the highlands have a regular income based on dairy farming (Fofifa 2018).More than 80 % of the milk is produced in the Vakinankaratra region, in mixed farms with less than five cows and a low individual average of 2,600 L cow -1 year -1 (Penot et al. 2016).The low milk productivity is mainly due to feed shortage, especially fodder.Fodder deficit is very intense during the dry season, from April to November.During this period, the natural pastures and crop residues are the main feed for ruminants.However, these resources are not suitable for dairy cattle feeding, as they are often high in fibre content and low in most essential nutrients, including protein, energy, minerals and vitamins that are required for rumen microbial fermentation (Asaolu et al. 2009).Therefore, this inhibits the productivity, health, body condition and reproduction of genetically improved dairy cattle.
Bamboo species are integral components of agroecosystems from the highlands to the coastal areas in the east and west of Madagascar.They can also be grown on a variety of soil types and are a fast growing plant species.Bamboo is commonly used for feeding humans and animals, fuel, pharmaceuticals, building materials and chemicals, and is also applied to environmental purposes, such as erosion control and carbon sequestration (Halvorson et al. 2010).
Research has been conducted on the use of bamboo leaves as fodder for several animal species, including cattle, sheep and goats (Hayashi et al. 2005, Asaolu et al. 2009, Halvorson et al. 2010), in many Asian and African countries.However, bamboo leaves have not been investigated as a fodder resource for dairy cattle in Madagascar, and information about their nutritive value is limited.The use of bamboo leaves as fodder in several developing countries needs to be further developed and tested (Antwi-Boasiko et al. 2011, INBAR 2019).
Due to its fast growth, high biomass production and wide adaptability of green leaves during winter months, bamboo can be an alternative source of fodder for dairy cattle and maintain their milk production during the dry season.The present study was carried out to assess the compositional information, as well as the optimal rate, of bamboo species as fodder for dairy cattle.

MATERIAL AND METHODS
The study was conducted at the Fiompiana Fambolena Malagasy Norveziana (Fifamanor), or At the laboratory, all bamboo leaf samples were finely chopped and dried in a hot air oven at 60 ºC, for 72 h.Then, they were ground using a hammer mill to pass a 1 mm screen and analyzed using wet chemistry (AOAC 1995).The quantity of residual dry matter was determined after drying in a hot air oven at 105 ºC, for 8 h.Total ash was analyzed by incineration at 550 ºC, for 8 h, in a muffle furnace.Crude protein was determined using the Kjeldahl method (Shaw 2006).The crude fibre content was obtained by incineration after acid and base digestion.Neutral detergent fibre and acid detergent fibre were determined using the procedures of Goering & Van Soest (1970).Acid detergent lignin was evaluated by subjecting acid detergent fibre residue to 72 % sulphuric acid.Cow faecal samples were dried in an air oven at 60 ºC, for 72 h.
Ten Norwegian Red Pied cows at first lactation, with a mean body weight of 417 ± 25 kg, were used during the experiment.The cows were selected and divided into five groups by balancing the milk amount, length of lactation and body weight.The experimental design was a 5 x 5 Latin square, with five treatments and five groups of animals.The five treatments comprised a control group, which was not receiving bamboo leaves in its diet and was compared to four experimental groups consuming, respectively, 25 %, 50 %, 75 % and 100 % of bamboo leaves in their diet.The groups of animals were interchanged across the different treatments every two weeks, including four days of adaptation and ten days of data collection.The total duration of the trial was ten weeks.
The amount of feed offered to each animal was calculated on the assumption that one animal can consume 3.0 kg of dry matter of forage per 100 kg of body weight per day.This amount was constant throughout the study and was distributed to each animal in two equal feeds at 07.00 a.m. and 4.00 p.m. Refusals from the previous days feeding were weighed every morning, before the new feeding, to allow the calculation of the daily intake.
Faeces of each animal were collected at 07.00 a.m. and 03.00 p.m. each day and weighed.In order to measure the dry matter apparent digestibility, about 500 g of faecal sample were collected per day, per animal, and analyzed.
The amount of milk produced by each cow was measured at 07.00 a.m. and 03.00 p.m.
The daily ration was composed of maize silage, bamboo leaves and concentrate feed (Table 1).Bambusa vulgaris and Dendrocalamus giganteus leaves were collected by cutting them at the stem level, in the eastern region of Madagascar, and transported weekly to the research centre.Maize was planted and ensiled at Fifamanor.To establish the diet, the two collected varieties of bamboo leaves were mixed each week to create a single ration of bamboo leaves.The raw bamboo leaves were then mixed with maize silage, according to the different proportions in the treatments, on the basis of the dry matter content.Cows in group 2 received 75 % of maize silage and 25 % of bamboo leaves (SIL75:BAM25).Those in group 3 consumed equally maize silage and bamboo leaves (SIL50:BAM50).Those in group 4 received 25 % of maize silage and 75 % of bamboo leaves (SIL25:BAM75).Cows in group 1 were offered an unrestricted sole diet of maize silage (SIL100:BAM0), while those in group 5 received an unrestricted sole diet of bamboo leaves (SIL0:BAM100).Each cow received 4.0 kg of concentrate feed per day, during the trial.The concentrate feed composition was different for each treatment, in order to balance the nutritional intakes of the diets by using the Inration software, version 3.3 (Table 2).Fresh and clean water was available ad libitum to the animals throughout the duration of the trial.
The statistical analysis used a one-way analysis of variance (Anova) for the data treatment, after processing the Shapiro-Wilk normality and Levene's variance homogeneity tests.Data were analyzed using the XLStat software, version 2008 6.03, copyright Addinsoft 1995-2008.A level of p < 0.05 was chosen as the minimum for testing the significance.Significant differences between means were compared using the Tukey test.

RESULTS AND DISCUSSION
The proximate compositions of sampled bamboo leaves are presented in Table 3.
The dry matter content ranged from 44.5 % in D. asper to 64.6 % in P. aurea, averaging 57.1 %; total ash from 6.68 % in B. bambos to 18.5 % in D. strictus, averaging 13.5 %; crude fibre from 25.9 % in D. strictus to 32.6 % in D. asper, with an overall mean of 29.1 %; and crude protein from 7.71 % in B. balcooa to 15.4 % in B. bambos, with an average of 12.5 %.The mean values for neutral detergent fibre, acid detergent fibre and acid detergent lignin across the species were, respectively, 76.2 %, 51.5 % and 12.1 %.P. aurea had the highest (79.3 %) neutral detergent fibre level, while D. giganteus had the lowest (72.4 %) one.The lowest content of acid detergent fibre was recorded in P. aurea (43.8 %) and the highest one in G. pseudoarundinacea (55.1 %).A small variation across the species from 10.4 % BAM: bamboo leaves; CP: crude protein; DM: dry matter; FUL: feed unit for lactation; RBP: rumen bypass protein; SIL: maize silage.The FUL unit corresponds to the amount of energy value in a feed and is obtained by finding the ratio of the net energy of the feed to the net energy provided by 1 kg of barley dry matter (1,700 kcal of net energy/kg of dry matter).In general, fodder species containing more than 30 % of dry matter and having 50 % of organic matter digestibility and less than 10 % of total ash content are considered a good fodder (Bhandari et al. 2015).A dry matter content of fresh fodder less than 15 % may restrict the voluntary intake in ruminants, as a higher water content within the plant cell causes bulkiness in the feeds (Tinworth et al. 1999).
The mean values for dry matter content in the bamboo species analyzed in the present study were well above 15 %.The total ash content is considered a good criterion of the total mineral content of the plant material.Excluding B. bambos, which had a total ash content of less than 10 %, the mean total ash content of all bamboo species was 14 %, which is considered acceptable.
Bhandari et al. ( 2015) reported crude protein contents of bamboo leaves averaging 12.3 % and ranging from 8.4 % to 17.1 %, which are comparable to our results.B. balcooa showed a particularly low crude protein content (less than 10 %), which is considered a poor quality feed, in terms of protein.
Indeed, below this level, the rumen fermentation is adversely affected (Norton 2003, Bhandari et al. 2015).A good fodder for dairy cattle needs around 18 % of crude protein, less than 30 % of acid detergent fibre and less than 40 % of neutral detergent ADF: acid detergent fibre; ADL: acid detergent lignin; CF: crude fibre; CP: crude protein; DM: dry matter; NDF: neutral detergent fibre; SD: standard deviation.2015), which ranged from 20.7 % to 45.9 % and averaged 26.5 %.Crude fibre is a measure of the quantity of feed indigestible components and has little nutritive value, but provides the bulk necessary for a proper peristaltic action in the intestinal tract and is important for maintaining the rumen health (McDonald et al. 2010, Bhardwaj et al. 2018).The higher the crude fibre content, the more indigestible the fodder will be, as it contains more lignin, a non-nutrient component.Indeed, lignin can be associated with polysaccharides and proteins, particularly in shrubs, making it difficult for rumen microbes to enzymatically degrade it.Only 30 % of the analyzed bamboo species contained crude fibre content above 30 %, what may be due to the maturity of the bamboo leaves, as the crude fibre content increases with the age and maturity of the plant species (Anele et al. 2008).

Bamboo
The measurement range of neutral detergent fibre was narrow, if compared to that reported by Bhandari et al. (2015), which varied from 61.7 % to 80.9 %, averaging 68.1 %.Neutral detergent fibre includes hemicellulose, cellulose, lignin, heat damaged protein and silica.It is strongly related to the feed voluntary intake and the availability of net energy from digestible energy (Bhandari et al. 2015).Generally, the neutral detergent fibre content of a fodder should be more than 25 % or 30 % (Upreti & Shrestha 2006).However, all the species analyzed had neutral detergent fibre contents over 70 %, and so were considered poor-quality fodder, in terms of fibre.
The acid detergent fibre contents of the bamboo species in the present study were comparable to those reported by Bhandari et al. (2015), which ranged from 41.3 % to 50.6 % and averaged 46.4 %.A higher value of acid detergent fibre represents a lower digestibility.Indeed, the digestibility of plant walls is strongly influenced by cellulose and lignin concentrations.These results confirm that the bamboo species available in Madagascar have a potential as fodder for ruminants.The high quantity of crude protein in the leaves of these bamboo species suggests that they are a good source of nitrogen supplement for ruminants that feed on poor-quality grasses and crop residues with low protein content, especially during the dry season.On average, the analyzed bamboo leaves had lower contents of protein than Lolium multiflorum (20 % of crude protein) and Avena sativa (15 % of crude protein), which are commonly planted and used during the dry season by farmers (Fifamanor 2009).The nutritive value of bamboo leaves was much better than that of crop residues such as rice straw (on average, 5 % of crude protein and 35 % of crude fibre), which is commonly fed to ruminants during this season.
The determination of the nutritional quality of bamboo leaves is an important aspect of ruminant feeding and a step towards creating a balanced diet (Bhandari et al. 2015).The knowledge of the nutritional potential of bamboo leaves in dairy cattle feeding will increase the adoption of these multipurpose resources by farmers.Bamboo leaves can provide an important component for ruminants diets and enable the maintainance of the animal performance throughout the year, especially during seasons of fodder shortage.However, it is also important to measure the nutrients intake and digestibility.
The dry matter intake of bamboo leaves was 1.6-7.1 kg of dry matter per day, with an average of 4.8 kg per day (Table 4).The SIL0:BAM100 treatment showed a significantly higher dry matter intake, while SIL75:BAM25 had the lowest one (p < 0.05).The dry matter apparent digestibility in bamboo leaves was significantly higher for SIL50:BAM50, at 56.4 % (p < 0.05).In contrast, the dry matter apparent digestibility was lower for SIL75:BAM25, at 37.4 % (p < 0.05).Concerning maize silage, the dry matter intake ranged from 2.1 kg per day to 8.5 kg per day, while the dry matter apparent digestibility ranged from 71.6 % to 74.6 %.SIL100:BAM0 had a significantly higher value for dry matter intake than the other treatments, while the intake of SIL25:BAM75 was lower, if compared to the other treatments (p < 0.05).Although the dry matter digestibility of maize silage was numerically higher in SIL50:BAM50, when compared to the other treatments, the differences were not significant (p > 0.05).
Intake values and the ingestion capacity of the animal determine its dry matter voluntary consumption.Generally, the intake of treatments where both bamboo and silage were offered (SIL25:BAM75, SIL50:BAM50 and SIL75:BAM25) were lower than those with single bamboo or silage (SIL0:BAM100 and SIL100:BAM0).The equal complementation of maize silage with bamboo leaves, which are rich in crude protein, was interesting, in terms of digestibility of both fodders.In contrast, the incorporation of 25 % of bamboo leaves improved the dry matter intake and digestibility of maize silage to the detriment of bamboo leaves.Bamboo leaves fed to animals during the trial were relatively mature and had a high fibre content.The animals tended to choose the maize silage over bamboo leaves, in a mixed diet of both fodders.Indeed, maize silage had a good intake and was very readily consumed by the dairy cattle, perhaps because it was less fibrous and less bulky (Vignau-Loustau & Huyghe 2008).The forage intake decreases with the age of the plants, as the proportions of stems, lignified tissues and cellwalls increase.In practice, a high fodder intake by animals can be achieved by harvesting plants at early stages.Hutjens (1998) also confirmed that roughage, which has higher contents of neutral detergent fibre, acid detergent fibre and acid detergent lignin, can restrict the consumption for ruminants.
Bamboo leaves and maize silage were nutritionally balanced and complementary.Vignau-Loustau & Huyghe (2008) reported that silage is an unbalanced forage, that has a high energetic value but a lower nitrogen value, with a crude protein content of less than 10 %.It is important to identify the optimal stage and period to harvest bamboo leaves, in order to achieve a moderate fibre content and improve intake and digestibility.
The daily milk production of dairy cows in the feeding trial provides an indication of the production value of the different diets.Bamboo leaf consumption enabled cows to maintain the milk production during the period of forage shortage, which varied from 13.6 L to 14.4 L per cow, per day, but displayed no significant difference between treatments (p > 0.05; Figure 1).SIL50:BAM50 showed the maximum milk production and SIL0:BAM100 the minimum one.
The incorporation of bamboo leaves into the basal diet of dairy cattle did not affect their milk production.Instead, bamboo leaves enabled the cows to achieve a milk production rate comparable to that seen with a sole diet of maize silage and concentrate feed.Bamboo provided an important constituent of daily rations for the ruminants (Datt et al. 2006, Bhandari et al. 2015).Among the available shrubs, bamboo can be exploited as forage, to reduce the fodder scarcity and feed ruminants and meet their nutritional requirements, especially during the dry season (Anurudu et al. 2004, Bhardwaj et al. 2018).The nutritional complementarity of maize silage and bamboo leaves could be leveraged in the daily ration of cows during the experiment.According to Delaby & Peyraud (2009), the combination of fodder with maize silage is beneficial, in terms of milk production.The high protein and mineral contents of bamboo leaves complemented the high energy content and intake of maize silage.Maize silage is often fed with forage in rations to balance the energy * Means in the same row without common letters are different (p < 0.05).BAM: bamboo leaves; DM: dry matter; p: p-value; SIL: maize silage.

Parameters
SIL0:BAM100 SIL25:BAM75 SIL50:BAM50 SIL75:BAM25 SIL100:BAM0  ) and the protein in the diet, as well as to improve the digestion quality (Gauthier 2016, Férard & Carel 2017).The diversity of forage species increases the forage availability and animal productivity in farms, ensuring the food security of farmers.
Furthermore, the collection and transport costs of bamboo leaves are not a constraint for farmers, especially if they are available close to the farms.Thus, the feed cost is reduced, improving the longterm viability and profitability of farms.At the time of harvesting bamboo culms for various uses, bamboo leaves can be recovered and fed to dairy cattle.Farmers can also integrate the bamboo cultivation to their forage system, in order to improve the feed sufficiency.Bamboo cultivation is also advantageous, in that it is a low input system and does not require irrigation.A thorough study including the effects of the harvesting stage of bamboo leaves, as well as the collecting season, on their chemical composition and nutritive value would identify the appropriate harvesting time for this forage.

CONCLUSION
Bamboo leaves have potential as a forage for ruminants in the highlands of Madagascar.Bamboo leaves are a good source of nitrogen for ruminants and may be complementary to silage in a mixed ration, without compromising the milk production.This allows cows to maintain their performance during the dry season, which is a period of forage shortage.Farmers can integrate bamboo cultivation in their forage system to enhance the feed sufficiency and diversity, in order to improve the animal productivity, as well as the food security.It is important to identify the optimal stage and period to harvest bamboo leaves, in order to reach a moderate fibre content and improve intake and digestibility.

Table 3 .
Chemical composition of bamboo leaves.

Table 2 .
Composition and nutritive value of concentrate feed per treatment.fibre.Fodder is considered low grade if the crude protein content is less than 8 %, acid detergent fibre is more than 45 % and neutral detergent fibre content is more than 65 % (Upreti & Shrestha 2006).B. bambos presented more than 15 % of crude protein content and was considered a good fodder.The other species had crude protein values between 10 % and 15 % and were considered to be of moderate quality.The use of forage resources that are rich in crude protein enabled reducing the concentrate feed in the ruminant diet, thus reducing the milk production cost.The crude fibre measurements obtained in the present study are comparable to those reported by Bhandari et al. (

Table 4 .
Mean intake and apparent digestibility of bamboo leaves and maize silage per treatment.