Productive performance of hair lambs , fed with fresh lemon pulp as an energy source

Objective. Evaluate the effect of the inclusion of different levels of fresh lemon pulp (FLP) was determined as a substitute of sorghum grain in the feeding of hair sheep in parameters of daily weight gain (DWG), daily food consumption (DFC), and feed conversion (FC), the nutritional composition of the ration was also determined. Materials and methods. The study was carried out using 20 hair ewes individually fed on a period of 75 days. The treatments were as follows: T1=0% FLP; T2=10% FLP; T3=20% FLP; and T4=30% FLP based on DM. A totally randomized design was used with five replicates per treatment. Concentrate and FLP were offered ad libitum as a mixture, registering the amounts of feed offered and rejected daily. Body weight was registered every 21 days for the DWG and analysis of nutritional composition of rations was performed. And for an analysis of daily food consumption. The data were evaluated through ANOVA in an entirely randomized design. Results. There was no meaningful difference (p>0.05) for the DWG that scored 97, 108, 103 and 103 g or for the FC that scored 9.62, 8.68, 9.31 and 10.23, respectively. For each treatment and for each DFC based on DM, a meaningful difference was observed (p<0.05) for T4 by replacing sorghum to 30%. Conclusions. FLP is an alternative to replace partially or completely the grains for hair ewes without lessening the evaluated parameters.


INTRODUCTION
In Mexico, sheep production is an adequate alternative for the production of food and other products (skin, wool, manure, etc.) because they are small ruminant animals that adapt easily to different environments and take advantage of the resources available in each region (1).
The main source of feed for sheep, as well as for other ruminants, is fodder; which growth and availability, as well as quality in the tropics, vary during the year, generating deficiencies in the availability of biomass and its nutritional properties, which is required by livestock (2).Due to these changes, in extreme conditions there is weight losses, deaths and an appreciable decrease in the continuity of the productive process of animals, so supplementary feeding is one of the elements that determine the productivity of the system (2).
As in all species, sheep need to meet nutrient requirements (3).Grain-based supplements or rations are often incorporated, which prices have increased and consequently production costs are higher (1), which makes it necessary to look for food alternatives for livestock maintenance (4-6).
There are several inputs that can be used to cover the nutritional requirements of sheep, since ruminants can use fibrous products and by-products that other non-ruminant animals cannot consume (3,6).
The State of Tamaulipas is a citrus producing region.In 2012 a production of 605 thousand tons was achieved between orange, lemon and grapefruit; of the total production, about 10%, is intended for the juice extraction industry.During this process, a large amount of by-product is obtained, producing residues from 45 to 60% of the fruit's weight, which is composed from 60 to 65% of the husk, from 30 to 35% of the pulp and from 0 to 10% of the seed; said residues constitute the fresh citrus pulp (FCP), Which can be used in animal feed (4,5).y pomelo; del total de producción, el 10% aproximadamente, se destina para la industria de extracción de jugo.Durante este proceso, se obtiene una gran cantidad de subproducto; generando residuos del 45 al 60% del peso del fruto, el cual está compuesto de 60 a 65% de cáscara, 30 a 35% de pulpa y 0 a 10% de semilla, dichos residuos constituyen la pulpa fresca de cítricos (PFC), la cual puede ser aprovechada en la alimentación animal (4,5).
Potentially the FCP can be considered as a source of highly fermentable and digestible fiber in the rumen, contributing quantities of energy substrates (4)(5)(6).In addition, this by-product is relatively cheap because the only cost is the transport from the juice fountain to the production unit.
On the other hand, Caparra et al (7) and Villanueva et al (4) indicated that the citrus residue is a low protein by-product and rich in soluble carbohydrates, in neutral detergent fiber; being an available source for the growth of rumen microorganisms.Dihigio et al (8) mentioned that, because of its energy content, FCP can be used as a substitute for cereals.
The purpose of this study was to evaluate the effect of fresh lemon pulp (FLP) at different levels, as a source of energy and as a substitute for sorghum grain, on the parameters of weight gain, food consumption and feed conversion, as a feeding alternative for hair lambs.

MATERIALS AND METHODS
Study area.The experimental work was carried out at the Zootechnical Site "Ing.Herminio Garcia Gonzalez" of the Faculty of Engineering and Sciences (FIC) of the Autonomous University of Tamaulipas (UAT), located at km 23 of the Victoria-Monterrey highway, in the Municipality of Güemez, Tamaulipas, Mexico.It is geographically located at 23° 45' 10" North latitude and 98° 59' 05"› West longitude, at an altitude of 145 meters above sea level, with predominant semi-dry and warm climate, with an average annual rainfall of 700 mm and average annual temperature of 22°C (9).
The bromatological analyzes of the rations used were conducted at the Nutrition and Food Quality Laboratory of the Faculty of Agronomy of the Autonomous University of Nuevo Leon, located in Gral.Escobedo, Nuevo Leon, Mexico.
Experimental units.Twenty hair lambs were selected from the Blackbelly, Pelibuey and Katahdin breeds, with an average live weight of 22.13±1.87kg.Later the ewes were dewormed with 0.5 mL of ivermectin.On the other hand, 2.5 mL of toxoid bacterium was applied subcutaneously, for symptomatic charcoal and malignant edema, and a dose (1 mL) of ADE vitamin was administered intramuscularly.
The ewes were randomly distributed into four groups and kept under housing conditions under a concrete floor in metal cages of approximately 2 m 2 , with individual feeders and drinking troughs.

Faustino-Lázaro et al -Lambs performance fed with fresh lemon pulp
The work lasted for 75 days and was divided into a pre-experimental phase of 12 days of adaptation and 63 days of testing.
The treatments evaluated corresponded to four experimental rations whose percentage composition consisted of: T 1 =0% of FLP and 30% of sorghum; T 2 =10% of FLP and 20% of sorghum; T 3 =20% of FLP and 10% of sorghum; and T 4 =30% of FLP and 0% of sorghum.The rest of the mixture is shown in table 1.The FLP used in this work consisted of lemon husk, pulp and seeds, which were acquired after the processing of lemons for the extraction of juice at a plant located 1 Km away from the production unit where the experiment was performed.
Ration analysis.To evaluate the chemical composition of each one of the rations, samples of approximately 300 g were taken and transferred to the Nutrition and Food Quality Laboratory of the Autonomous University of Nuevo Leon, Faculty of Agronomy at Gral.Escobedo, Nuevo Leon, Mexico .The analyzes were determined in duplicate for each one of the characteristics.The content of dry matter (DM), ashes (C), crude protein (CP) and ethereal extract (EE) (AOAC 10).While neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HEM), cellulose (CEL) and lignin (LIG) were performed according to the protocols of Van Soest et al (11).
The in vitro digestibility of the DM (IVDMD) of rations was determined using a ruminal fermenter methodology (Daisy II, Ankom Technology ® , USA).The preparation of the culture medium and inoculum, as well as the determination of the digestibility of dry matter, was based on the protocol proposed by the fermentor supplier (Daisy II, Ankom Technology ® , USA).
The determination of the gross energy content (GE) was calculated with the data generated in the adiabatic calorimetric pump (Parr ® , 1241 USA).The content of digestible energy (DE) and metabolizable energy (ME) was calculated considering the GE and IVDMD of the samples.Experimental design.A completely randomized design was used with four treatments and five replicates.Each treatment was applied to a group of ewes to which food and water were freely provided on a daily basis.The variables evaluated were: daily food intake (DFI), daily weight gain (DWG) and feed conversion (FC).
The DWG of animals was determined by weighing them at the beginning of the experimental phase and then with a frequency of every 7 days, with a fasting of 12 hours prior to weighing.
La GDP de los animales se determinó pesando al inicio de la fase experimental y posteriormente con una frecuencia de cada 7 días, con ayuno de 12 horas previo a la pesada.
Consumption of DM (DFI) was estimated on a daily basis, by weighing the amount of food offered and subtracting the amount of food rejected.
The FC was calculated by dividing the food intake by the total weight gain obtained.
The productive behavior of ewes was determined using the following (covariance analysis) model: Where: Y ij = Response variable in the j-th repetition of the i-th treatment, μ = Overall average, T i = Effect of the i-th ration, X ij = Initial weight of the j-th ewe, β = regression coefficient that relates Y ij to the variable X ij and ε ij = Random error (12).
The chemical composition of the rations was determined using the following model: Where: Y ij = Response variable in the i-th treatment and j-th repetition, μ = Overall average, T i = Effect of the i-th treatment and ε ij = Experimental error (12).
In the cases where there were significant statistical differences (12), Tukey's mean comparison tests were applied with a significance level of (p<0.05).

RESULTS
The results of the chemical composition of the rations used in the feeding of ewes are detailed in table 1, which shows that the ash content decreased when the level of substitution of the sorghum by FLP was increased up to 20%, observing significant differences (p<0.05).Similarly, the behavior on CP was reduced to the extent that the higher level of substitution of sorghum by FLP was reached; showing differences (p<0.05)where T 4 had a lower value (8.29% CP) than T 1 (10.35%CP).
The EE content did not show any significant difference (p>0.05),showing values of 4.90, 5.71, 6.86 and 7.44% for T 1 , T 2 , T 3 and T 4 , respectively.
For the fiber fractions NDF, ADF and CEL, significant differences (p<0.05) were obtained with lower values of T 1 , with respect to the other treatments, which were similar to each other (p>0.05).The sorghum substitution level radically affected the fiber fractions, increasing their values (48.62 to 52.51, 30.77 to 35.69 and 24.15 to 28.90%, respectively for NDF, ADF and CEL).However, the HEM content was lower in T 4 , showing significant
The content of GE, DE and ME of the rations was increased with respect to the level of sorghum substitution by FLP.A quadratic trend (Figure 2) was observed (by determination coefficients greater than p=0.93) in the energy level of the ration by having a higher level of substitution of sorghum by FLP.Regarding the ME for this work, the rations with the highest energy content were T 3 and T 4 (2.14 and 2.16 Mcal kg -1 DM, respectively), being higher (p<0.05)than T 1 and T 2 , which also showed significant statistical differences among themselves (Figure 2).
En lo que respecta al contenido de EE, los valores obtenidos fueron mayores a los reportados por Bampidis y Robinson (4) en una revisión exhaustiva de subproductos citrícolas.De igual modo, Villanueva et al ( 5) reportaron valores where T 3 was the intermediate value.However, FC was not different (p>0.05) between treatments (Table 2).Con los resultados de este trabajo se concluye que la PFL, se puede aprovechar, hasta el 30% de la dieta, en sustitución del sorgo, en la content of fresh orange pulp (6.0%) as compared to sorghum with 11.2% as reported by Villanueva et al (5).Similarly, Bampidis and Robinson (4), in their review of citrus fruit by-products, found that the CP content is about 9.0%; likewise, there are other texts in the literature that mention similar values (6,13).
Regarding the EE content, the values obtained were higher than those reported by Bampidis and Robinson (4) in an exhaustive review of citrus fruit by-products.Similarly, Villanueva et al (5) reported values of 2.1% for EE when using 15, 20, 25 and 30% of fresh orange peel pulp in rations for fattening hair lambs.However, Dadvar et al (13) found values of 7.06% for EE.
In this study lignin showed values higher than those reported by Villanueva et al ( 5) and González et al (6).
The results obtained for the IVDMD of the rations used increased as the level of FLP increased (Figure 1), until obtaining a value of 68.1% for T 3 (20% of FLP).Macias-Cruz et al (14) reported that increasing fresh orange pulp in rations from 30 to 40%, the IVDMD improved from 80.6 to 84.2%, so it is expected than an increase in IVDMD will raise the ME level in the ration.However, Dadvar et al (13) found that IVDMD was 60.45%.
The increase in the inclusion level of FLP in the ration is associated with the increase in ME, as observed in figure 1; which can be attributed to the high pectin content (15).In this regard, Villanueva et al (5) reported values of 2.3 and 3.2 Mcal kg -1 for the nutritional content of sorghum and FLP, respectively, which allows improving the content of ME in the ration.
Productive behavior of ewes.The values for of DFI recorded in this study were lower than those reported by Cienfuegos-Rivas et al (16), in lambs fed with rations that included dehydrated orange pulp, in which consumption was higher as the level of residue increased.Similarly, Macias-Cruz et al (14), when including up to 30% of fresh orange pulp, obtained a quadratic behavior in consumption (1.13, 1.22, 1.34 and 1.32 kg d -1 ) of diets that included 0, 15, 30 and 45% of pulp, respectively.However, the results of this study are different from those reported by Villanueva et al (5), with DFI of 1.35, 1.22, 1.07 and 0.97 kg by incorporating 15, 20, 25, and 30% of fresh orange pulp in the rations.
Considering the results obtained for DWG, it is possible to mention that these are lower than those reported by Pascual-Cordova et al (17) in Pelibuey lambs, with 192 g d -1 , using whole diets with a ME content of 2.8 Mcal kg -1 and 19.8% of CP.Similarly, alimentación de corderas de pelo, sin afectar los parámetros productivos de GDP y CAL de las corderas de pelo.
Del mismo modo, se considera a la PFL una alternativa como fuente energética para sustituir al grano de sorgo en la alimentación de corderas de pelo.

Agradecimientos
Al Consejo Nacional de Ciencia y Tecnología por la beca otorgada al primer autor y al Programa de Fortalecimiento Académico para Indígenas.
A la Facultad de Ingeniería y Ciencias de la Universidad Autónoma de Tamaulipas y a la Universidad Autónoma de Nuevo León.
Cienfuegos-Rivas et al (16) found that the DWGs were higher in Dorper x Pelibuey hair lambs.
From the results of this work it can be concluded that FLP can be used, up to 30% of diet, as a replacement of sorghum in the feeding of hair lambs, without affecting the productive parameters of DWG and FC of hair lambs.
Similarly, the FLP is considered an alternative energy source to substitute sorghum grain in the feeding of hair lambs.

Figure 1 .
Figure 1.In vitro digestibility in rations with different levels of substitution of sorghum for fresh lemon pulp.

a, b
Averages with different letter in the same row are different Tukey (p<0.05);IVDMD = in vitro dry matter digestibility, R 2 = determination coefficient (%); GE= gross energy; DE = digestible energy; ME = metabolizable energy.

Figure 2 .
Figure 2. Behavior of the level of gross energy (GE), digestible energy (DE) and metabolizable energy (ME) in rations with different levels of substitution of sorghum for fresh lemon pulp.