R. El-Banna1, H. A. Abdellatif1  And G. Rakha2


1Dept. of Nutrition and Clinical Nutrition , 2 Dept. Of Medicine and Infectious Diseases,

 Fac. of Vet. Med., Cairo Univ. Giza ,Egypt



Fifty male buffaloes were randomly allotted to one of two treatment groups.  Control group (20 males with initial weight 254.9±4.7 kg ) was fed a ration without lasalocid supplementation.  Lasalocid group (30 males with  initial weight of 249.7±3.3 kg) was fed the control ration with the addition of 300 mg lasalocid/head/day for 142 days.  Measurements included body weight gain, feed:gain ratio, rumen protozoal density and activity, and total and individual ruminal volatile fatty acid concentrations.  Lasalocid-fed group had significantly higher (P<.01) final body weight (410.58±3.6 kg vs. 395.57 ± 5.05 kg ; ADG 1.13± 0.2 kg vs. 0.98±0.1 kg) than the non supplemented group.  Feed:gain ratio was improved due to lasalocid supplementation. Feeding lasalocid increased both rumen protozoal density and motility. No differences among treatments were observed for ruminal pH (P>.05). Total VFA production was increased in lasalocid-fed group. Acetic acid molar % was significantly reduced (P<.05) in lasalocid-fed group. Molar proportions of propionic, butyric and valeric acids were increased due to lasalocid supplementation but this increase was insignificant.  It can be concluded from this study that addition of 300 mg lasalocid/h/d to fattening buffaloes improves body weight gain and feed:gain ratio by altering rumen VFA in favor of better performance.

Keywords: Buffaloes, Lasalocid, Performance, VFA



The efficient conversion of feed energy into animal products (milk and meat) is important to maintain profitability of livestock enterprises.  Ionophores such as lasalocid and monensin increase the efficiency of converting feed into body tissue by growing beef animals (Goodrich et al., 1984). Lasalocid (carboxylic ionophore) is considered as a rumen fermentation modifier which alters the pattern of rumen fermentation in a way which increases the total nutrients supply to the animal and reduces energy loss associated with carbohydrate fermentation in the rumen, most notably a reduced acetate : propionate ratio, in both vitro and in vivo studies (Richardson et al., 1976; Bartley et al., 1979; Fuller and Johnson, 1981; Schelling et al., 1984; Duff et al., 1995; Wessels et al., 1996).

Lasalocid and monensin cause a shift in the proportions of fermentation end products with a very little effect on total acid production.  It has been suggested that propionate is used more efficiently for body weight gain than is acetate (Blaxter and Wainman 1964).  

Ionophores cause  a characteristic decrease in molar proportion of ruminal acetate and butyrate, along with corresponding increase in the molar proportion of propionate which is mainly used for weight gain (Brown and Hogue, 1985; Baran et al., 1986 and Lepzien et al., 1986).

Drennan and Roche (1981), Givens et al. (1981) and Morris et al. (1990) reported that monensin and lasalocid had no effect on ruminal pH, total and individual volatile fatty acid, while, Badawy (1992) recorded that monensin did not affect ruminal pH and TVFA with an increase in propionate production in buffaloes.

Ionophores inhibit extensive protein degradation or amino acid deamination in the rumen and thus decrease ammonia production (Van Nevel and Demeyer, 1977 and Spears et al., 1989).

Subsequent investigations, however, have revealed several other metabolic effects, including decreased methane and lactic acid production, inhibition of protozoa and gram-positive bacteria, decreased rate of passage and rumen turnover, increased fiber and starch digestibility, and decreased ruminal protein degradation and deamination (Schelling, 1984).  The net effect of the above fermentation changes may include reduced feed consumption, improved protein utilization, reduced incidence and severity of lactic acidosis and bloat. 

Response to volatile fatty acids in vivo may be related to the type of diet (concentrate vs. roughage) or to type of grain or grain processing.  Moreover, differential effects of ionophores between in vitro and in vivo experiments might result from differences in diets or substrates or from adaptation to ionophores in vivo (Gaylean and Owens 1988).

Until writing up this manuscript, papers published on the effect of lasalocid in buffaloes are scarce, therefore, this experiment was designed in order to evaluate the response of male buffaloes to lasalocid supplementation on growth and rumen parameters, so as to offer the experiment results to buffalo producers as a reference. 



Fifty male buffaloes averaging (249-254 kg) were allotted randomly into two treatment groups.  Treatments were control (20 animals) or control diet plus 300 mg lasalocid/h/d (30 animals). During the 142-day study, animals were fed a total mixed ration (TMR) at a private farm in Menoufeya Province.  Diet composition is given in table 1.  Animals were weighed every 28-day before feeding and the average daily gain (ADG) was calculated. Daily feed intake was determined each day by subtracting the unconsumed feed from total feed offered the previous day and feed:gain ratio was calculated.    

Rumen samples were collected 2 hours after feeding via stomach tube and pH was measured immediately as well as activity of rumen protozoa was recorded under the microscope at the farm.  Rumen samples were then strained through cheesecloth, after which the fluid was centrifuged at 1,000 x g for 10 min and the supernatant was used for VFA determination according to the method of Bartley et al. (1979).

Statistical Analysis: Student t test was performed to compare between the 2 groups using Statview 512 + (1986).


Table (1):  Composition of total mixed ration fed during the experiment.


Ingredient                                                                   % fed as

Corn silage                                                                    25.00

Ground corn                                                                  56.00

Soybean meal 44% CP                                                  12.00

Linseed meal                                                                    5.00

Limestone                                                                       1.20

Salt                                                                                 0.50

Vitamin and trace element premixa                                    0.30

Calculated analysis:

DM  %                                                                           73.50

CP %                                                                           12.24

TDN    %                                                                     60.30

Ca %                                                                              0.54

P %                                                                                 0.29  

NEm (Mcal/kg)                                                                1.47

NEg (Mcal/kg)                                                                 0.99

ADF     %                                                                        5.80

NDF     %                                                                       10.74

a 12,000,000 IU, vitamin A; 2,000,000 IU, vitamin D; 15,000 mg vitamin E; 250 mg selenium; 1,000 mg cobalt; 4,000 mg iodine; 20,000 mg copper; 50,000 mg iron; 70,000 mg manganese, and 60,000 mg zinc/ 3 kg premix.



Lasalocid is fed commonly to growing beef cattle to improve rate of gain and feed efficiency (DM intake/ BW gain).  Generally, lasalocid increases rate of gain and feed efficiency when fed to growing beef animals (Bergen and Bates 1984).


Performance Data:

Data concerning body weight, average daily gain and feed:gain ratio are presented in table 2. Final body weight and average daily gain were significantly higher (p =.01) as a result of feeding lasalocid .

Lasalocid supplementation at the rate of 300 mg/h/d resulted in 15% increase in ADG. DMI was not significantly different between groups, however, feed:gain ratio was improved by 13.6% in lasalocid-fed group. The increased weight gain, average daily gain and improved feed: gain ratio observed with the lasalocid-fed group are also in agreement with other reports in cattle (Bartley et al., 1979; Brethour, 1979; Berger and Rick 1980; Gutierrez et al., 1982; Neunedorff et al., 1985 and Ibrahim 1997) who used high energy diets in their experiments. However, others reported no significant effect on feed intake or body weight gain as a result of lasalocid supplementation (Berger et al., 1981; Delfino et al., 1988 and Wessels et al., 1996). Differences in diet composition and the level of lasalocid used in such experiments were probably largely responsible for the variable results between studies.


Table (2): Effect of Feeding Lasalocid on Overall Performance of Fattening Buffaloes.

Item                              Control                Lasalocid                       P value

Initial BW, kg                 254.94                     249.79                         NS

                                       ±4.78                         ±3.33

Final BW, kg                 395.57                         410.58                       0.012

                                        ±5.05                         ±3.65

ADG, kg                            0.98                          1.13                          0.01

                                         ± 0.1                          ±0.2

DMI, kg                             7.31                          7.28                                  NS

                                        ±0.18                           ±0.22

Feed/gain                           7.46                             6.44                     P <.05

Values are means±SE

NS non significant


Fermentation Parameters:

Rumen volatile fatty acids (VFA) results are presented in table 3.  Values are shown as means±SE for samples collected  3 times (every 30 days) throughout the experiment. No differences were observed among treatments (P>.05) for ruminal pH (table 3); this agrees with data of Paterson et al. (1983), Poos et al.  (1979), Morris et al. (1990), Knowlton et al. (1996) and Wessles et al. (1996) and Ibrahim (1997).  Ionophores prevented acidosis and maintained ruminal pH of beef cattle that were ruminally infused with starch or glucose mixtures (Nagaraja et al. 1981).  On high starch diets, protozoa play a buffering role in the rumen, consuming both starch  and also bacteria that degrade starch and produce lactate (Hungate 1966) which could be explained by the increased activity of protozoa in the lasalocid supplemented group in the present study. 


Table (3): Effect of Lasalocid supplementation on some rumen fermentation parameters.

Item                                                     Control                                Lasalocid

Rumen protozoa                                    Active                               Very active

pH                                                        5.58                                        5.50

                                                            ±0.05                                      ±0.35

Ammonia N,  mg/dl                               17.64                                      22.8

                                                            ±1.72                                      ±1.64

TVFA mEq/dl                                       11.15                                       16.00

                                                            ±1.73                                      ±2.27

Acetic a molar %                                  51.63a                                     43.79b

                                                            ±2.8                                         ±3.09

Propionic a molar %                              23.08                                        25.23

                                                            ±1.14                                        ±1.75

Butyric a molar %                                 16.27                                        19.29

                                                            ±2.3                                          ±0.74

Isovaleric a molar %                              4.20                                            5.44

                                                            ±1.29                                        ±2.39

Valeric a molar %                                 4.82                                            6.25

                                                            ±0.27                                        ±2.86

Values are means±SE

a,b Means within rows with different superscripts are significantly different (P<.05).


            Ruminal ammonia N concentrations are presented in table 3. Ruminal ammonia N was unaffected by lasalocid supplementation and averaged 17.64 and 22.8 mg/dl for the control and lasalocid groups respectively. This numerical increase in the lasalocid group was insignificant (P>.05) which agrees with others Rick et al. (1984); Spears and Harvey (1984); Funk et al. (1986); Reffett-Stable et al. (1989); Morris et al. (1990); Quigley et al. (1992) and Wessels et al. (1996) who reported no effect of lasalocid on ruminal ammonia concentrations.  Although other researchers reported that lasalocid increased the ruminal concentrations of NH3 in sheep fed a diet of alfalfa and corn (Ricke et al. 1984) and cattle grazing winter wheat pasture (Anderson and Horn (1987).  On the other hand, Ibrahim (1997) reported a significantly lower value for ruminal ammonia N due to lasalocid supplementation.  Such variable results between studies are probably because of the difference in the nitrogen source and diet composition. 

Total and individual VFA values are shown in table 3.  There were no significant differences among treatments (11.15±1.72 vs. 16.0±1.64 Meq/100 ml) in relation to total VFA which is consistent with other studies Bartley et al., (1979); Gutierrez et al., (1982); Neuendorff et al., (1985); Morris et al., (1990) and Wessels et al., (1996) and Ibrahim (1997).

The molar proportion of acetic acid was significantly lower (P<.05) in the lasalocid group (43.97±3.09 %) than  in the control group (51.63±2.87 %).  Meanwhile, the molar proportion of propionic acid was numerically higher in the lasalocid supplemented group than the control group as shown in table 3.  These findings are in agreement with Schelling (1984); Neuendorff et al., (1985); Reffett-Stabel et al., (1989).

Molar proportions of  butyric, isovaleric and valeric were numerically increased in the lasalocid supplemented group as shown in table 3, however, such increase was not statistically different (P>.05).  These results also agree with those reported by Ibrahim (1997).

The results of the present study explain the improved performance as manifested by increased final BW, ADG and feed/gain ratio in the lasalocid supplemented group, which is a possible explanation for the mode of action of lasalocid. Dennis et al., (1981) found that bacteria that were resistant to lasalocid were either lactate fermenters or succinate producers.  Consequently, increased propionate production would result from selecting for succinate producers and lactate fermenters.  Another mode of action of lasalocid is the reduction of methanogenesis by inhibiting formic acid and hydrogen producing bacteria, the precursors of methane (Chen and Wolin, 1979).

The increased final BW, ADG and improved feed/gain as well as alterations in rumen VFA observed with lasalocid-supplemented buffaloes suggest that addition of the ionophore to buffaloes diets could be an effective management tool for producers.  



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