Evaluation of rations supplemented with fibrolytic enzyme on dairy cows performance 3. Productive performance of lactating Friesian cows

M I Bassiouni, H M A Gaafar*, A M A Mohi El-Din*, A M Metwally and M A H Elshora*

Department of Animal Production, Faculty of Agriculture, Kafrelsheikh University, Egypt
* Animal Production Research Institute, Agricultural Research Center, Dokki, Giza, Egypt
dr.gaafar@hotmail.com

Abstract

Thirty multiparous lactating Friesian cows with body weight of 500±25 kg were used during the first 20 weeks of lactation. Cows were randomly assigned to six similar groups (5 in each) and fed the experimental rations consisted on DM basis of 60 % concentrate feed mixture (CFM) + 40 % berseem hay without  (BH) or with fibrozyme (BH-E), corn silage without  (CS) or with fibrozyme (CS-E) or rice straw without  (RS) or with fibrozyme (RS-E). Fibrozyme was added at level of 1 g/kg DM.

Results showed that cows fed ration containing CS-E showed the highest DM and TDN intake and those fed ration based on BH-E had the highest DCP intake,  those fed ration containing RS recorded the lowest intake (P<0.05). The BH-E ration showed the highest digestibility coefficients of DM, OM, CP and CF and DCP value, while CS-E the highest EE digestibility and TDN value.  

Cows fed CS-E ration had significantly (P<0.05) the lowest pH value and the highest TVFA's concentration, while those fed BH ration revealed the highest NH₃-N concentration. The pH value decreased, but TVFA's and NH₃-N concentrations increased gradually until 4 hours after feeding then showed opposite trend at 6 hours.

Cows fed CS-E ration recorded significantly (P<0.05) the highest actual milk and 4% FCM yield and the percentages of fat, lactose and TS in milk, while those fed BH-E had the highest protein and SNF percentages (P<0.05).

Cows fed CS-E recorded the lowest requirements of DM and TDN per kg FCM, while those fed RS-E showed the lowest DCP/ kg FCM (P<0.05). Cows fed RS ration revealed the lowest average daily feed cost, wile those fed CS-E recorded the lowest feed cost/ kg FCM and the highest income of FCM and economic efficiency.

Keywords: digestibility, economic efficiency, feed conversion, milk yield and composition, rumen activity

Introduction

In the different regions of the world, forages are used as a unique feed source for ruminants due to their abundance and low cost. However, their availability and quality are not constant throughout the year. Moreover, the digestion of forages in the rumen is relatively slow and incomplete, limiting animal performance and increasing feed cost of livestock production. Tropical forages in particular have limited energy value and its cell wall contents are rich in lignin, silica and that limit carbohydrate fermentation and therefore the VFA production and microbial mass in the rumen (Dominguez Bello and Escobar 1997).

Recent studies indicated that, adding fibrolytic enzymes to ruminant diets improved nutrient digestibility (Kung et al 2000 and Murillo et al 2000), growth rate (Ali 2006) and milk production (Rode et al 1999 and Zheng et al 2000). Moreover, fibrolytic enzymes were more effective when added to either concentrate or roughage portion of diets in early lactation period. These enzymes increased milk yield by 6 to 16% in Lactating dairy cows (Lewis et al 1999; Yang et al 2000). Furthermore, enzyme application was more effective with lower forage to concentrate ratio (38:62) than higher ratios (55:45, 57:43 and 60:40). Therefore, the effect of the dietary component to which the enzyme is added may depend on the forage to concentrate ratio and the uniformity of enzyme application to these components (Adesogan 2005).

Beauchemin et al (2003) indicated that using fibrolytic enzymes improves forage utilization and productive efficiency of ruminants and, adding enzymes to high-concentrate diets gave more consistent results than with high-roughage diets. They also found that, improvement in animal performance due to enzyme additives could be attributed mainly to improvements in ruminal fiber digestion resulting in an increase of digestible energy intake.

Ruminal pH plays an important role in fiber digestion, because the growth of ruminal fiber digesting bacteria is strictly limited at pH less than 6.00 (Russell and Wilson 1996) who hypothesize that the relative magnitude of the benefit to enzyme supplementation is a least partially dependent on ruminal pH (Murillo et al 2000).

Dairy cows fed forage treated with a fibrolytic enzyme additive ate more feed and produced 5 to 25% more milk (Lewis et al 1995; Stokes and Zheng 1995). The beneficial effects of fibrolytic enzymes in ruminant diets appear to be a result of, in part, improvements in feed digestibility (Beauchemin et al 1995,1999, Feng et al 1996, Lewis et al 1995; Yang et al 1999). If exogenous feed enzymes increase the digestibility of the diet, the beneficial effects on animal performance are likely to be greatest for ruminants in negative energy balance, such as cows in early lactation.

The objective of the present study was to investigate the effect of fibrolytic enzyme (Fibrozyme) additive on feed intake, digestibility, milk production and composition, rumen fermentation, feed and economic efficiency of lactating Friesian cows.

Materials and methods 

Experimental animal and rations

Thirty multiparous lactating Friesian cows with body weight of 500±25 kg were used during the first 20 weeks of lactation. Cows were randomly assigned to six similar groups (5 in each) and fed the experimental rations consisted on DM basis as follows:

BH    : 60% concentrate feed mixture (CFM) + 40% berseem hay (BH) without enzyme.

BH-E: 60% CFM + 40% BH with 1 g enzyme / kg DM.

CS    : 60% CFM + 40% corn silage (CS) without enzyme.

CS-E: 60% CFM + 40% CS with1 g enzyme/ kg DM.

RS    : 60% CFM + 40% rice straw (RS) without enzyme.

RS-E: 60% CFM + 40% RS wit1 g enzyme/ kg DM.

Fibrolytic enzyme (fibrozyme) ingredients are Aspergillus niger, Trichodema longibrchiatum, fermentation extracts and fermentation solubles. Also, it contains 20% CP, 8% ash and 100 U xylanase / g (International Free Trade Co., Cairo, Egypt). The fibrozyme was added to the feedstuff at the level of 1 g/kg DM, diluted with water at 100 g/liter and sprayed with 10 ml per kg of feedstuffs according to the procedure stated by Kung et al (2000).

Cows were individually fed the experimental rations to cover the recommended requirements for dairy cows according to NRC (2001). Feeding allowances were adjusted every week according to changes in body weight and milk production. Concentrate feed mixture was fed in two equal meals daily at 8 a.m. and 4 p.m., while berseem hay, corn silage or rice straw was fed once daily at 10 a.m. Cows were watered three times daily at 7 a.m., 1 and 7 p.m.

The total duration of the trial was 20 weeks.

Milk yield and sampling

Individual cows were milked mechanically, morning and evening milk yields were recorded daily for each cow and the 4% fat corrected milk (FCM) for each cow was calculated from daily milk yield and the percentage of milk fat using the formula given by Gains (1928) as follows: 

 4% FCM = [0.4 X milk yield (kg)] + [15 X fat yield (kg)].

Milk samples were taken biweekly from the consecutive evening and morning milking for each cow and mixed in proportion to milk yield.  Composite milk samples were analyzed for fat, protein, lactose, solids not fat (SNF), and total solids (TS) by milko scan, model 133B.

Digestibility trials

Six digestibility trials were carried out during the feeding trial using three cows from each group to determine the nutrients digestibility coefficients and nutritive values of the experimental rations using acid insoluble ash (AIA) as a natural marker (Van Keulen and Young 1977). Feces samples were taken from the rectum of each cow twice daily with 12 hours interval during the collection period (last week of experiment). Samples of tested rations were taken at the beginning, middle and end of collection period. Samples of tested rations and feces were dried in a forced air oven at 60 ^oC for 48 hours, then pooled for each animal, ground and chemically analyzed according to the methods of AOAC (1990). Nutrient digestibility coefficients and nutritive value was calculated from the equation stated by Schneider and Flatt (1975).

DM digestibility (%) = 100 – [100* AIA % in feed/ AIA % in feces]

Digestibility (%) of proximate analysis components = 100 – [100*AIA % in feed *component % in feed/ AIA % in feces* component % in feces]

Rumen liquor samples

Rumen samples were collected from the cows using a rubber stomach tube connected withdrawal plus power of the automatic milking machine. Samples were collected three times during the experimental period at 0, 3, 6 hours after the morning feeding. Every sample was strained through four layers cheesecloth. Ruminal pH value was determined directly, ammonia–nitrogen concentration was determined by using magnesium oxide (MgO) as described by AOAC (1990). Total volatile fatly acids (TVFA's) were determined by steam distillation method as described by Warner (1964).

Feed conversion

Feed conversion was determined as the amounts of DM, TDN and DCP required for producing 1 kg 4% FCM.

Economic evaluation

Economic efficiency was calculated according to the following formula:
 

Where: price of 1 tonne concentrate mixture = 1600 LE, berseem hay = 800 LE, rice straw = 100 LE, corn silage = 150 LE, fibrozyme = 10 LE/kg and FCM = 2 LE/ kg.

Statistical analysis

Data were subjected to statistical analysis using general linear models procedure adapted by SPSS for windows (2004) for user’s guide with one-way ANOVA. Duncan test within program SPSS was done to determine the degree of significance between the means (Duncan 1955).

Results and discussion 

Chemical composition of experimental rations

Calculated chemical composition of experimental rations is shown in Table 1.

 Results revealed that CP content was higher in rations contained BH, NFE content was higher in rations contained CS and CF and fiber fractions contents were higher in rations contained RS. These results reflect the chemical composition of concentrate feed mixture, berseem hay, corn silage and rice straw.

Feed intake

Effect of roughage type and fibrozyme supplementation on average daily feed intake is shown in Table 2.

Cows fed ration contained CS  recorded the highest DM and TDN intake and those fed ration contained BH  had the highest DCP intake, however, those fed ration contained RS  showed the lowest intake of DM, TDN and DCP (P<0.05). Moreover, the intake of TDN increased significantly (P<0.05) with fibrozyme supplementation. The interaction between roughage and enzyme supplementation revealed that cows fed CS-E recorded the highest DM and TDN intake and those fed BH-E had the highest DCP intake (P<0.05). These results agreed with those obtained by Pinos-Rodriguez et al (2002) who found that feed DM intake by lambs was not affected by enzyme. Bowman et al (2002) reported that DM intake was not significantly altered, but digestible DM intake increased significantly by inclusion of enzyme. The intake of DM by cows fed rations contained RS tended to lower than the recommended requirement, while the intake of TDN and DCP by cows fed rations contained BH and CS were higher than the recommended requirements (NRC 2001).

Digestibility coefficients

Digestibility coefficients of experimental rations by cows are presented in Table 3.

BH rations showed the highest digestibility coefficients of DM and CF, while those containing CS had the highest digestibility coefficients of OM, CP and EE (P<0.05). Moreover, the digestibility coefficients of all nutrients increased significantly (P<0.05) with fibrozyme supplementation. The BH-E ration showed the highest digestibility coefficients of DM, OM, CP and CF, CS-E the highest EE digestibility and RS-E the highest NFE digestibility (P<0.05). These results agreed with those obtained by Bowman et al (2002) who found that cows receiving enzyme treated ration had a significantly higher DM, OM, NDF and ADF digestibility compared to cows receiving control ration. There was significant improvement in the diet digestibility of DM, OM, CP, NDF, ADF and total carbohydrates (TC) between the control and enzyme treated diets by goats (Prokasananda et al 2009).

Nutritive values

Nutritive values of the experimental rations are presented in Table 3. Ration based on CS showed the significantly (P<0.05) highest TDN value and those containing BH had the highest DCP value, while those having RS had the lowest TDN and DCP values. Moreover, the TDN value increased significantly (P<0.05) with fibrozyme supplementation. The CS-E ration recorded the highest TDN value and BH-E ration the highest DCP value (P<0.05). These results agreed with those obtained by Rode et al (1999) who found that total digestibility of nutrients was dramatically increased by enzyme treatment. Dean et al (2005) and Adesogan et al (2005) reported that enzyme improved the nutritive value of the diet.

Rumen liquor parameters

Ruminal liquor parameters during the different times are shown in Table 4.

Cows fed rations containing CS recorded the highest TVFA's and the lowest pH value, but those fed rations based on RS had the opposite trends (P<0.05). While, cows fed rations containing BH  showed the highest NH₃-N concentration and those fed ration containing RS   had the lowest concentration (P<0.05). Moreover, ruminal pH value and NH₃-N concentration decreased, while the concentration of TVFA's increased significantly (P<0.05) with fibrozyme supplementation.

The ruminal pH values were higher before feeding and decreased gradually until 4 hours after feeding then increased at 6 hours. However, the concentrations of TVFA's and NH₃-N was lower before feeding and increased gradually until 4 hours after feeding then decreased at 6 hours. The CS-E had significantly (P<0.05) the lowest pH value and the highest TVFA's concentration and BH ration revealed the highest NH₃-N concentration. These results are in accordance with those obtained by Adesogan et al (2005) who found that ruminal fluid pH tended to be lower in cows fed enzyme than in those fed the control diet, presumably due to easier enzymatic hydrolysis of the concentrate than the roughage into readily fermentable substrates that depress pH when fermented. Mean ruminal NH₃-N concentration was lower significantly in cows fed enzyme treated diet than in cows fed the control diet. This suggests that there was enhanced uptake of NH₃-N by the ruminal microbes probably due to greater fermentable metabolizable energy from this diet. Van Soest (1963) stated that the optimum pH value for growth of cellulytic microorganisms was 6.7 and the range for normal condition was about ± 0.5 pH degree. Russell and Dombrowski (1980) reported that ruminal total VFA production was closely related to ruminal pH, which can be considered an important regulator of microbial yield. Ruminal microorganisms utilize more NH₃-N when more energy sources are fermented (Hungate 1966).

Milk yield

The effect of roughage type and fibrozyme supplementation on actual milk and 4% FCM yield are shown in Table 5.

Cows fed CS rations  recorded the highest actual milk and 4% FCM yield followed by those fed ration based BH , but those fed rations having RS  had the lowest yield (P<0.05). The yield of actual milk and 4% FCM increased significantly (P<0.05) with fibrozyme supplementation by 8.28 and 10.42%, respectively. Cows fed CS-E ration recorded significantly (P<0.05) the highest actual milk and 4% FCM yield. The increase associated with feeding ration containing CS is attributed to the increase dietary non-fiber carbohydrates concentration particularly starch (Table 1), which increased the ruminal total VFA production (Table 4). These results agreed with those obtained by Schingoethe et al (1999) who reported that enzyme induced increase in milk production occurred during the first 100 day postpartum dairy cows. Adesogan et al (2005) found that enzyme application increased milk yield in dairy cows. Prokasananda et al (2009) showed 180 to 260 ml/day of higher FCM for goats fed enzyme treated diet compared with control diet.

Milk composition

The percentages of all milk constituents as affected by roughage type and enzyme supplementation are presented in Table 5. Cows fed rations containing CS  recorded the highest percentages of fat, lactose and TS in milk and those fed BH rations  showed the highest percentages of protein and SNF, however those fed rations having  RS  had the lowest protein percentage (P<0.05). Only fat percentage increased significantly (P<0.05), but the other constituents were insignificantly increased (P>0.05) with fibrozyme supplementation. Cows fed CS-E ration showed the highest fat, lactose and TS percentages, while those fed BH-E had the highest protein and SNF percentages (P<0.05). These results are in accordance with those obtained by Saleh (2007), Zeid et al (2008) and Khattab et al (2009) they found fibrozyme supplementation led to significant increase in the percentages of milk constituents in cows and buffaloes.

Feed conversion

Feed conversion by lactating Friesian cows as shown in Table 6 revealed that cows fed rations with RS  recorded the highest amounts of DM and TDN per 1 kg FCM followed by those fed rations containing BH , while those fed rations having CS  had the lowest amounts (P<0.05).

However, cows fed ration contained BH  recorded the higher amount of DCP per 1 kg FCM followed by those fed ration contained CS , while those fed ration contained RS  had the lowest amount. Fibrozyme supplementation led to significant (P<0.05) decrease in the amount of DM per kg FCM. Cows fed CS-E recorded the lowest requirements of DM and TDN per kg FCM, while those fed RS-E showed the lowest DCP/ kg FCM (P<0.05). These results agreed with those obtained by Saleh (2007) who indicated that the amounts of DM, TDN and DCP required per kg FCM decreased with fibrozyme supplementation. Adesogan et al (2005) found that enzyme supplementation increased feed efficiency. Prokasananda et al (2009) reported that feed intake g/kg FCM yield in goats was also 7% less in enzyme treated diet compared with control diet.

Economic efficiency

Results in Table 6 showed that cows fed rations contained BH showed the highest average daily feed cost (ADFC) followed by those fed rations contained CS, while those fed rations contained RS had the lowest cost (P<0.05). However, average daily feed cost did not significantly (P<0.05) affected by fibrozyme supplementation. Feed cost / kg FCM (FC/FCM) was significantly higher (P<0.05) for cows fed BH rations compared with those fed CS rations and RS rations and it decreased significantly (P<0.05) with fibrozyme supplementation. Cows fed CS rations recorded the highest income of FCM yield (IFCM) and economic efficiency (EE) as the ratio between income of FCM yield and daily feed cost followed by those fed BH rations, while those fed RS rations had the lowest output and their increased significantly (P<0.05) with enzyme supplementation. Cows fed RS ration revealed the lowest average daily feed cost, wile those fed CS-E recorded the lowest feed cost/ kg FCM and the highest income of FCM and economic efficiency. These results agreed with those obtained by Saleh (2007) who found that feed cost as LE/ kg FCM decreased and economic return increased with fibrozyme supplementation for dairy cows. Zeid et al (2008) reported that average daily feed cost, output of milk yield and economic efficiency increased with fibrozyme supplementation for dairy cows.

Conclusion   

• Cows fed the ration that contained corn silage with fibrozyme supplementation (CS-E) showed the best results concerning digestibility, feed intake, rumen liquor parameters, milk yield and composition, feed conversion and economic efficiency.   

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Received 5 May 2010; Accepted 16 May 2010; Published 10 June 2010

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