Effect of Inclusion of Albizia saman Pods in the Diet on the Performances of Dairy Cows

Corresponding Author: Min Aung Department of Physiology and Biochemistry, University of Veterinary Science, Yezin, Nay Pyi Taw, Myanmar Email: minaung.uvs@gmail.com Abstract: Ruminants can achieve high productivity when the diet includes concentrates; however these are often expensive due to competition with humans and mono-gastric animals. This experiment was conducted to determine the effect of partial inclusion of Albizia saman pods (ASP) in a Commercial Concentrate (CC) on the performances of dairy cows. Twelve cross-bred Holstein Friesian cows (472±13 kg) in the 12th week of lactation were randomly allocated into four treatment groups with three replicates accoding to the completely randomized design. The four treatments were control diet-CD [35% urea-treated-rice-straw (URS; 79g crude protein (CP)/ kg dry matter (DM)) and 65% CC (contained 40% cottonseed cake, 35% broken chickpea and 25% chickpea husk on an as fed basis and provided 200g CP/kg DM)], D1[35% URS + 60% CC + 5% ASP (189g CP/kg DM)], D2 (35% URS +55% CC + 10% ASP) and D3 (35% URS + 50% CC + 15% ASP). Cows were fed treatments for 60 days. Dry matter intake was significantly higher (p<0.05) for cows in the D3 treatment compared with the other three treatments, however there were no significant differences in the DM digestibility of treatments. Nitrogen intake and faecal-nitrogen of cows offered the D3 treatment were significantly higher (p<0.05) than those of cows offered the other three treatments. In contrast urine-nitrogen and nitrogen utilization were not significantly different among the treatments. The average milk yield (4% fat-corrected-milk) increased as the percentage of ASP was increased in the diets, however the composition of milk did not differ significantly between treatments. The costs of TDN/kg and per kg of milk was highest for the CD treatment and the lowest was found in D3 treatment (p<0.05). These results suggest that Albizia saman pods could be replace up to 15% of the commercial concentrate fed to lactating Holstein Friesian cross-bred cows without detrimental effects.


Introduction
The ruminants can achieve high productivity with the supplementation of concentrates in the diets. However these are often expensive due to competition with humans and mono-gastric animals. Therefore, many researchers have been considering the alternative ways to replace for the concentrates. In the region of Asia, Africa and Pacific, the tree leaves and pods have been traditionally used as sources of forage for ruminants (Le Houérou, 1980). Among them, Albizia saman pods (ASP) are highly palatable and suitable as a feed supplement in dry season (Durr, 2001). ASP are black brown, oblong, lumpy and filled with a sticky, brownish pulp that is sweet and edible (Staples and Elevitch, 2006). Moreover, ASP has the advantage for the enhancing microbial growth in the rumen of cattle because of its higher values of digestibility, total sugar and protein contents (Jetana et al., 2010).
However, ASP contained the low level of toxic substances such as tannin. The low level of dietary condensed tannin (2-3%) has the beneficial effects to the ruminants and reduces the wasteful protein degradation in the rumen (Barry, 1987). Consumption of higher amount of tannin (>5%) significantly reduces voluntary feed intake, while medium or low consumption (<5%) did not affect on the feed intake (Barry and Duncan, 1984;Barry and Manley, 1984;Waghorn et al., 1994).
ASP were used as a valuable feed supplement in the pasture system for cattle, goats and sheep (Flores, 2002). Using ASP, the feed cost for the ruminants can be significantly reduced (Hosamani et al., 2005). Babayemi and Igbekoyi (2008) stated that ASP could be replaced guinea grass up to 40% for silage as dry season feed without detrimental effects on performances of WAD ram. Adeniji et al. (2010) also reported that ensiling with cassava wastes and ASP would give a good feed resource, however sole diet as a dry season feed for sheep might be unsuitable, but their Conversely, there was still little information on the use of ASP for ruminant feed, especially for the feed of dairy cattle. Therefore, this experiment was conducted to determine the effect of partial inclusion of ASP in the commercial concentrate (CC) on the performances of dairy cows.

Measurements
During the feeding trial, all of the feedstuffs were weighed and sampled before feeding. Moreover, milk yield was also recorded three consecutive days in one week. Milk was analyzed once in every two weeks with Lactoscan. During collection period, milk samples, feedstuffs offered samples and refused (orts) samples were collected for chemical analysis. The orts were weighed and sampled before morning feeding and then removed. Faeces voided and urine outputs were recorded daily during the collection period.

Chemical Analysis
Ground samples of feed offered, residues (orts) and faeces were analyzed for DM, organic matter (OM) and ether extract (EE) by the method described by AOAC (1990) and analyzed for neutral detergent fibre (NDF) and acid detergent fibre (ADF) by Goering and Van Soest (1970). Faeces and urine were analyzed for nitrogen by using Kjeldahl method (Fross 2020 digester and Foss 2100 Kjeltec distillation unit) and CP was calculated as 6.25 × N (AOAC, 1990).

Statistical Analysis
The data were subjected to the analysis of variance (ANOVA) and the significance of differences between treatments means were compared by Duncan's Multiple Range Test (DMRT) using SPSS (version 16.0) software.

Results and Discussion
The chemical compositions of ASP shown in Table 1 were consistent to the report of Hosamani et al. (2005;Babayemi et al., 2010). Nutrient intakes dry matter intake (DMI), organic matter intake (OMI) and crude protein intake (CPI)] of cows fed on D3 were significantly higher (p<0.05) than those of cows fed on other diets (Table 2). This finding was consistent with the reports of Babayemi and Igbekoyi (2008) and Adeniji et al. (2010) who reported that the feed intake of sheep could be improved with the increased inclusion level of ASP ensiling and cassava waste. ASP are palatable (Durr, 2001) and filled with a sticky, brownish pulp that is sweet and edible (Staples and Elevitch, 2006) and rich in soluble carbohydrate. The supplementation of starch in diets linearly increased the amount of OM digested and outflow rates of solid and liquid which resulted the increased microbial yield. The increased passage of microbial protein to the small intestine occurred as a result of the increased passage of both fluids and solids with increased intake (Gomes et al., 1994;Djouvinov and Todorov, 1994).
Although all of digestibilities were not significantly different (p>0.05) among them, it was noted that dry matter digestibility (DMD), organic matter digestibility (OMD) and crude protein digestibility (CPD) slightly decreased when inclusion level of ASP was increased in the diets (Table 3). This finding supports the report of Babayemi and Igbekoyi (2008). They observed that DMD, OMD and CPD slightly decreased when the inclusion level of ASP was increased in the ensiling guinea grass diet for sheep. The greater amount of sugar contained in ASP might decrease pH and cellulolytic microbial activity in the rumen which depressed the fibre digestion (Hoover, 1986). Increasing the inclusion level of ASP in the diets increased the feed intake which leads to decrease digestibility. This assumption agreed with the finding of Tyrrel and Moe (1975) who reported that the digestibility of dairy cow diets was reduced with increasing intake. Moreover, the changes in digestibility observed with increased intake have been associated with reduced digesta retention time in the rumen.       Table 6.  Nitrogen intake and faecal-nitrogen of cows offered the D3 were significantly higher (p<0.05) than those of cows offered the other three treatments (Table 4). In contrast urine-nitrogen and nitrogen utilization were not significantly different (p>0.05) among the animals offered the experimental diets. It might be due to the higher output of the faecal-nitrogen. This assumption agreed whit the report of Yan et al. (2010), who stated that the main factor influencing the excretion of nitrogen from dairy cows was protein intake and there was a very strong and positive relationship between manure nitrogen output and dietary protein intake. Moreover, when the level of ASP was increased in the diets, the amount of the hard seeds contained in the ASP was also increased. All of these seeds could not be digested by the ruminants and contained in the faeces after passing through the digestive tract.

Milk composition (%) of dairy cattle offered experimental diets Experimental diets -----------------------------------------------------------------------------------
Although, the average milk yield (4% fat-correctedmilk) were not statistically different (p>0.05), increasing the percentage of ASP in the diets lead to slightly higher in milk yield (11.99, 12.05, 12.77, 13.02 kg/day for CD, D1, D2 and D3, respectively) ( Table 5). This findings was consistent with the report of Anantasook et al. (2015), who observed that the supplementation of ASP into the basal diets of dairy cows improved the rumen environment and increased milk yield contents (protein and milk fat). It could be due to the higher amount of readily fermentable carbohydrate (sugar) contained in ASP. The end product of fermentation of starch and sugar is propionate. Increased propionic acid concentration in the rumen lead to increase lactic acid and glucose production, which improved the milk yield of host animals. Moreover, most of energy needed for live weight gain and for the mammary system to produce lactose, is also obtained from propionate. Another reason for this finding is the low level tannin included in ASP which increased the milk yield of animal with the reduceing of the wasteful protein degradation and increaseing microbial protein synthesis in the rumen. Schwab and Boucher (2005) presented that deficiency of rumen degradable protein (RDP) lead to poor microbial growth which reduce microbial protein synthesis, carbohydrate digestion, feed intake and consequently milk production.
The composition of milk did not differ significantly between treatments; however, milk fat percentage of cows fed on D3 was slightly decreased than those of others (Table 6). While the inclusion level of ASP was increased in the diets, the fibre content (NDF and ADF) was slightly decreased and increased the amount of sugar content of diets which decreased the milk fat content. An alteration in rumen fermentation and availability of endogenous fatty acid sources were probably involved in the causes of decreasing milk fat content (Christie, 1979). Feeding of readily fermentable carbohydrates depressed fiber digestion and pH of rumen. Therefore, it decreased acetic and butyric acid production and increased propionic acid production. Increased propionic acid concentration in the rumen lead to increase lactic acid and glucose production which stimulated insulin production, reducing free fatty acid release from adipose tissue. Therefore, the production of acetic and butyric acids, the main precursors of milk fat, could be affected by diet through changes in rumen fermentation or addition of fats in diets. Moreover, in 1980 and 1989, Sutton reported again that milk fat concentration was affected by the amount of fibre, the forage-to-concentrate ratio, the carbohydrate content of concentrate mix, lipids, intake and meal frequency.
The costs of TDN/kg and per kg of milk produced was highest for the CD treatment and lowest for D3 treatment (p<0.05) ( Table 7). According to this result, it was found that cost for each group decreased when the inclusion level of ASP was increased. The cost for ASP and CC were 61 and 316 kyats per kg, respectively. It might be the main reason for the feed cost effectiveness of all treatment groups.

Conclusion
According to the results, Albizia saman pods could be replace up to 15% of the commercial concentrate fed to lactating Holstein Friesian cross-bred cows without detrimental effects.