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Effect of blocks with calcium propionate on lamb productive performance and in vitro GHG
Abstract
Objective. Evaluate multinutritional blocks with and without calcium propionate (Ca-Pr) on digestibility and live weight changes of lambs and in the green house emission in vitro. Materials and methods. Twelve lambs were used (20.17±2.35 Katahdin x criollo) in three treatments: Basal diet (BD 70% oat straw, 30% concentrate), BD+ Block without Ca-Pr and BD+ Block with 1.5% Ca-Pr in 50 days assay. In vitro gas production (GP) and kinetic parameters were estimated (Vmax, S, Lag). In vitro and in vivo, CH4, CO2 and digestibility were estimated. Results. The dry matter intake was the lowest (p<0.0001) in lambs without block (753 g/d) compared lambs supplemented with block without (839 g) or with Ca-Pr (828 g); including blocks increased methane (16.16 and 16.18 g/d; 0 and 1.5% Ca-Pr respectively) than BD (13.93 g/d). The GP in vitro was higher (p=0.0001) with BD (380.76, ml) than with blocks without differences among blocks (335.76 and 341.13 ml, 0 and 1.5% Ca-Pr respectively), and the BD had higher (p=0.0001) production of CH4 (47.16 mol) and CO2 (200.04 mol) than with blocks (42.25 and 41.58 mol CH4; 179.21 and 176.39 mol CO2; 0 and 1.5% Ca-Pr respectively). Conclusions. Block supplementation improved dry matter intake. Blocks reduced in vitro gas production and increased digestibility by reducing CH4 and CO2.
Main Text
INTRODUCTION
Studies have been conducted to evaluate the contribution of ruminants to greenhouse gas (GHG) emissions and alternatives to mitigate this problem (1), which represent up to 12% of the energy consumed (2). To reduce these losses and make ruminant production more efficient, the use of additives has been evaluated (3,4), were sometimes have not improved yield (5) or fermentation (6) and the most efficient ones, such as Ionophores have been banned because are antibiotics. Calcium propionate (Ca-Pr) as an unconventional food ingredient has been used in lambs to reduce the use of grains, increasing ruminal propionate (7). Its potential to reduce methane is explained by the fact that during its dissociation captures a hydrogen ion, reducing its availability to form methane (8). The GHG emissions can be reduced if digestibility is improved, which is achieved by meeting nutritional requirements, particularly in ruminants fed diets low quality forages (9).
One option to an option to complement the deficiencies is to supplement with multinutritional blocks (MB) that have been evaluated worldwide (10), however, animal response has not been constant because for many years FAO promoted a block formula for all the conditions (11) when the nutrient requirements are different for each physiological stage with a diversity of basal diets. Therefore, the objective of this experiment was to evaluate multinutritional blocks formulated to improve lambs growth fed a basal diet with low nutritional value, with or without Ca-Pr, evaluating the impact on lamb growth, digestibility and in GHG emissions in vivo and in vitro.
MATERIALS AND METHODS
Location. This work was carried out in the facilities of the UAEM University Center in the Zootechnical Post of the Autonomous University of the State of Mexico, Amecameca, State of Mexico located in the south eastern zone of the State of Mexico.
Weather conditions. Subhumid temperate climate with an annual average temperature of 14.7°C.
Animals. Twelve Katahdin x creole lambs (20.17±2.35 initial weight) housed in individual cages with access to feed and clean water ad libitum were used. This work was carried out under the guidelines of the Academic Committee of the Department of Animal Science, in accordance with the regulations established by the Animal Protection Law of the State of Mexico, Mexico.
Treatments. The experiment lasted 50 days and lambs were distributed in a Completely Randomized Design (n=4 lambs) in three treatments: basal diet without supplement (BD: 70% corn stover, 30% concentrate, Table 1), BD with access a multinutritional block with or without 1.5% of Ca-Pr (Alimentaria Mexicana Bekarem, Mexico City) (Table 2).
Basal diet and blocks wereoffered ad libitum. The basal diet was designed to simulate thoseoffered in family-type production units (11% protein, 2.7 Mcal/kg DM ME). Themultinutritional blocks (MB) were formulated so that when were supplementedfulfilled the nutritional requirements for lambs according to the NRC (12) fora weight gain of 150 g/d estimating an intake of 100 g/d block. The basal dietand blocks were analyzed to determine: dry matter (DM), organic matter (OM),crude protein (CP) (13), neutral detergent fiber (NDF) and acid detergent fiber(ADF) (14) (Table 3). The lambs were weighed with a 12-hour fast. On day 24,fecal samples were collected for four consecutive days to determine total tractDM digestibility using insoluble acid ash as an internal marker (15).
CH4 and CO2 estimation in vivo. The IPCC equations were used (16) to estimate the ruminal CH4 using the annual emission factor (EF) per lamb, where the Ym or fraction for gross energy of the feed transformed to CH4 was calculated using the digestibility of each treatment with lamb’s equations (17). Carbon dioxide emissions were estimated from the intake of digestible carbohydrates (18), which were used to estimate the moles of hexose fermented in the rumen using the molecular weight of anhydrous glucose (19). The fermentation pattern was from the forage: concentrated ratio and the produced moles of CO2 were calculated from the stoichiometric equations of Wolin (20).
Kinetics of in vitro gas. The gas production derived from ruminal fermentation was determined by the in vitro gas technique (21). The BD was used as substrate incubated with each MB in a proportion of 5% of the basal diet. Prior to incubation, the substrates were dried at 55 °C for 48 h in an oven and milled (<2 mm). In 500 ml amber flasks, 500 mg of each treatment were placed. Flasks were then incubated in anaerobic conditions with 90 ml of a diluted inoculum (1:10) of rumen bacteria obtained from two fasted lambs. The flasks were hermetically sealed and incubated at 39°C for 72 h in a water bath. The volume of gas produced was recorded at 2, 4, 6, 8, 12, 16, 20, 24, 30, 36, 42, 48, 60 and 72 h and the pressure values transformed to gas volume with the equation of linear regression, used to estimate the parameters of the gas production kinetics: maximum gas volume (Vm; mL g-1 DM of the substrate), gas production rate (S; h-1) and the lag time of the fermentation (L; h), with the model: Vo=Vm/(1+ e (2-4 * s * (t-L))) (21). At the end of the fermentation the residual dry matter (DM) was obtained to calculate in vitro dry matter digestibility (DIVDM) at 72 h of incubation; each treatment was incubated in triplicate.
CH4 and CO2 estimation in vitro. Those gases were estimated from the maximum gas volume; short chain fatty acids were calculated with the Getachew equation (22) and the proportion of CH4 and carbon dioxide with the stoichiometric factors 0.538 mmol for CO2 and 0.348 mmol for CH4 that have been described in other in vitro studies (23).
Experimental design. The data from each experiment were analyzed according to a Completely Randomized Design with a generalized linear model using each lamb as an experimental unit in the in vivo experiment or the test parameters obtained from the in vitro incubations, considering the treatments as fixed effects and random errors associated with each observation. The means of the treatments were compared using the Tukey test (p=0.05). For the in vivo experiment the initial weight was analyzed as a covariate using the JMP software (24). In vitro gas kinetics parameters were estimated for Vo=Vm/(1+ e (2-4 * s * (t-L))) using non-linear models of the JMP. A simple correlation between GHG results in vivo and in vitro was estimated.
RESULTS
The multinutritionalblocks supplementation increased dry matter intake (p<0.01) by 10%, however,no differences were found in other variables (Table 4). Block supplementationdid not reduce daily methane and CO2 emissions due to increased feedintake. The lambs that consumed blocks with Ca-Pr did not reduce intake nor hadan effect on the estimated GHG emissions.
Table 5 shows the invitro gas parameters. The basal diet resulted with a high volume of gas(p<0.001) and as a consequence, more moles of CH4 and CO2were produced (p<0.0001). There were no differences between the blocks dueto the inclusion of Ca-Pr. In vitro digestibility was not affected byblock supplementation. In vitro digestibility values ​​werecorrelated with those observed in vivo (r=0.9964, p=0.054), and invivo digestibility was associated with daily weight gain (r=0.997,p=0.0434). The CH4 and CO2 emissions were positivelycorrelated with the dry matter consumption (r=0.9921, p=0.07, r=0.9920,p=0.08). CH4 and CO2in vivo and in vitroshowed a high negative correlation (r=-0.99, p=0.07, r=-0.99, p=0.07)
DISCUSSION
As observed in this experiment, it has been reported that MB stimulate intake (25) but there are studies where blocks had no effect (26). The composition of the blocks can modify intake (10); there are interactions between nutrient in the block and in the basal diet. In those studies, where intake was improved, generally a greater daily gains or final weight have been observed and in some cases, this is associated with greater digestibility (9) and nutrient consumption. In this study, the gain was improved by 35% but the low number of repetitions and the variation did not allow to detect differences. The type of block can have different effects on intake and digestion, by modifying the energy source, it was affected the block consumption without affecting digestibility (25).
The incorporation of Ca-Pr in the MB did not improve lamb performance or carbon dioxide emissions. If the values ​​of CH4 and CO2in vivo were expressed per kg of DM consumed, similar values would result (BD 1.84, 1.95 and 1.92 per MB with 0 or 1.5% Ca-Pr), indicating that the consumption of blocks and their additives were insufficient to modify the ruminal fermentation. In other evaluations, Ca-Pr did not affect the intake or lambs performance, 1% MS (7) and above 5.5% DM (27) the amount consumed in the MB was below of those studies. In vitro gas results indicate that MBs would reduce CH4, but in vivo values ​​contradict this as they increase intake. Caution should be exercised in extrapolating the results of in vitro gas studies where no in vivo data are presented (28). With respect to other parameters of in vitro gas, it has been reported that 1% Ca-Pr increases the Lag phase but does not affect the fermentation pattern or CH4 losses (29).
In another in vitro study with 10% of Ca-Pr, the volume of gas increased, which was attributed to the effects on pH and osmotic pressure (8). In an in vivo evaluation with bulls receiving 20 g/d of Ca-Pr, did not affect fermentation or the microbial population (30), but the dose was very low.
The use of MB could reduce the lamb’s time to reach the final weight by 44 or 60 days by supplementing without or with Ca-Pr respectively, reducing daily emissions, and could be an alternative to reduce global GHG emissions. Most studies focus on daily data, but it is important to consider the effects and their impact on global warming in terms of time (21).
In conclusion, supplementation with multinutritional blocks in low quality diets improved intake. In vitro the blocks reduced gas production and increased digestibility, so they could potentially reduce methane and carbon dioxide emissions.
Conflict of interests.
The authors declare no conflict of interests.
Abstract
Main Text
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION