Effect of the supplementation with multinutritional blocks of pitaya (Stenocereus griseus L.) on the live weight gain of goats in the low Mixteca of Oaxaca, México

The effect of the use of pitaya (Stenocereus griseus L.) and urea multi-nutritional blocks (MNB) on liveweight gain and body condition of goats in the Low Mixteca region of Oaxaca was evaluated. An experiment with participating farmers was carried out using a randomised block design, with five treatments consisting in levels of 50% ( SG50), 45% ( SG45), 40% ( SG40) and 35% ( SG35) of Stenocereus griseus L. fruit, plus an only-grazing control treatment (CTL), with five animals per treatment, over a 75 day period.

MNB showed ranges of crude protein (CP) between 29.2 and 36.1%. The highest intake was of 69.9 g/day for SG40, with a liveweight gain of 11.0 g/day and a cost of $ 0.13/day. Body condition improved in all treatments compared with the control. Farmers were interviewed afterwards, and 75% considered that MNB can prevent weight loss during the intense drought season. The interviewees recommended further use of MNB incorporating also other fruits of local cacti (Stenocereus stellatus and Escontria chiotilla); dry pods of Acacia cimbispina Sprague, Acacia farnesiana and Prosopis laevigata; leaves from wild shrubs and native grasses. It was shown that pitaya-urea MNB are a technically and economically viable alternative for supplementing goats in the region.

Keywords: Body condition, goats, intake, liveweight gain, low Mixteca, multi-nutritional blocks

Introduction

In Mexico the arid and semi-arid zones occupy 54.3% of the national territory, around 90 million hectares, dominated by xerophilous shrub and semi-desert grassland (Valencia 2006). Most rural inhabitants live in these areas (PNDPI 2001) and depend on small-scale farming. A representative semi-arid region is the Mixteca (Hernandez et al 2001) with an approximate area of 40,000 km², covering territory of the states of Puebla, Guerrero and Oaxaca (Dubravka 2003).

The Mixteca of Oaxaca comprises three areas, Low, High and Coast. In the Low Mixteca, the dominant vegetation consists of trees, shrubs and cacti. Livelihoods depend on rainfed agriculture, livestock production for self-consumption and financial contributions from relatives who have migrated to big cities or the United States (Berumen 2004, Velásquez 2002). Goat production is based on extensive grazing, using forage trees, shrubs and native grasses (Sierra et al 1998, Silva and Mora 1989). Production of these forages decays drastically in the dry season (January to June), resulting in general liveweight loss.

The use of local resources and the adaptation of technologies using participatory approaches are a high-priority for community development (Arriaga et al 1998). The use of multi-nutritional blocks (MNB) composed of molasses as an energy source and urea as a source of non-protein nitrogen (NPN) has been extensively evaluated in developing countries, mainly in cattle (Makkar et al 2007). This technology can be adapted to goat production in the Low Mixteca of Oaxaca in the dry season using local products (Miller and Thomson 2003, Hadjipanayiotou 1996), increasing microbial protein synthesis and improving forage use, whilst providing macro and micronutrients (Ben Salem and Nefzaoui 2003, Osuna et al 1996, Leng et al 1991). Technology transfer, process and adoption of MNB are appropriate for small landowners who do not have easy access to extension services. It is practical in arid areas where grazing is subject to prolonged dry seasons, and forage and crop wastes are deficient in energy and nutrients but high in fiber (Forsberg et al 2002, Anindo et al 1998, Ricca and Campbell 1993, Robleto et al 1992, Sansoucy 1986).

Soriano et al (2004) proposed the integration of local cacti fruits as an alternative for feeding small ruminants in the Low Mixteca of Oaxaca. Two promising species in the region are Stenocereus griseus and Stenocereus stellatus, due to their wide availability, along with the local scarcity of sugar cane molasses. The wastes of maize and beans can also be incorporated as fibrous ingredients for the elaboration of MNB. The objective of this study was to evaluate the use of MNB made of fruits of Stenocereus griseus and its effect on body condition and liveweigth gain in goats maintained in extensive grazing conditions in semi-arid zones.

Methodology

Study Area

The study was conducted in the municipality of Cosoltepec, located in the northwestern part of the state of Oaxaca, in the Low Mixteca region, coordinates 97° 47' W and 18° 08' N. The climate is semiarid with xeric shrub of great biodiversity in forages, medicinal plants and cacti. The average annual temperature ranges between 25° and 30° C. Peak altitude above sea level is 1825 m, and rainfall varies between 300 and 400 mm per year distributed between July and September (Trejo 2004). Soils have been formed from the disintegration and decomposition of igneous, sedimentary and metamorphic rocks resulting in young soils called Regosols (IUSS 2007) which conform mountain ranges and hills, with poor organic matter and high amounts of calcium carbonate (INEGI 2004).

Procedure

Five farmers were directly involved. They built a pen and divided it into five compartments, provided their animals and collected the ingredients for the elaboration of the MNB. The blocks were made according to the procedures described by Sansoucy (1986) and García and Restrepo (1995). MNB resistance was measured with a soil penetrometer, reaching at 21 days a resistance of 4 kg/cm², estimated as safe for consumption (Araujo-Febres et al 1997, Pulgar-Lugo et al 1997). The blocks were then stored for later use.

25 local (creoles) male goats in growth were used, with an initial average weight of 20 kg. The animals were dewormed and tagged, weighted at the beginning of the experiment and then every month. Body condition was measured at the beginning and at the end of the experiment according to the scale proposed by Catton and Petrie (2002), with values from 0 to 5 according to the general physiological state of the animal.

A randomized block design was used, with 5 treatments and 5 animals per treatment. The treatments had levels of fruits of Stenocereus griseus L. of 50% and 0% molasses ( SG50), 45% and 5% molasses ( SG45), 40% and 10% molasses ( SG40), 35% and 15% molasses ( SG35), plus an only-grazing control (CTL). The animals had free access to water in the usual places of the grazing routes. Measured parameters were: MNB consumption (g/day), weight gain (g/day) and body condition. Samples were taken from the MNB for chemical composition analysis (AOAC 1990).

The MNB were administered during the critical drought period (January to June). The experiment began with a period of adaptation to the MNB of 15 days, in order to check the hardiness of the blocks, the management by the farmers and possible symptoms of intoxication. The experimental period lasted for 75 days. In the adaptation period the goats had access to the blocks an hour before grazing, whilst in the experimental period this was four hours prior to grazing. The obtained results were subjected to analysis of variance and the means were compared using a Tukey test (Steel and Torrie 1986). For the costs of the elaboration of MNB all ingredients were taken into account, including fruit picking work in the orchard, ground stubble, elaboration and transportation. Finally, a semi-structured survey (Geilfus 2002) with 21 questions was applied to 16 farmers, which included the five participating ones plus 11 who observed the development of the experiment. The subjects covered were: knowledge and utility of the MNB, raw materials, recommendations and local resources available for MNB elaboration.

Results and discussion

Blocks were 15 cm high by 17 cm diameter, and compacted using a metal rammer. However, MNB that only contained juice of Stenocereus griseus were more voluminous and fragile in spite of storage time and the hardness obtained, and split apart when eaten by goats. This was not observed in the MNB with 10% and 15% sugar cane molasses, ingredient that gives better compaction and is highly palatable, as observed in other studies (Arias et al 2005, Forsberg et al 2002). Levels of molasses between 40 and 50% (Osuna et al 1996) influence the compaction of the fibrous material used, independent of the fineness of the grind and lime used (Fernandez et al 1997, Araujo-Febres et al 1997). Hardiness influences consumption, and also depends on the proportion of cement, lime and storage time. For fast setting, lime and cement have shown better results (Araujo-Febres et al 1997, Osuna et al 1996). In this study, the results of the adaptation period suggested increasing the levels of lime and cement from 7 to 7.5% each for the experimental period.

Chemical composition

In the adaptation period (Table 1) the amount of urea was fixed at 2.5%, lower than the toxicity limit recommended by Rodriguez (1985) of 3%, considering that in the region animals do not have access to NPN supplements.

Table 1. Ingredients used in the MNB for the adaptation period, %.
Ingrédients	SG50	SG45	SG40	SG35
Molasses	0	20	30	40
Stenocereus griseus L.	50	20	10	0
Urea	2.5	2.5	2.5	2.5
Common salt	5	5	5	5
Mineral mixture	2	2	2	2
Lime	7	7	7	7
Cement	7	7	7	7
Corn stubble	26.5	36.5	36.5	36.5

The average concentration of crude protein of the MNB in this period was 12.5%, with a high percentage of ash (35.3%) due to the lime and cement. The chemical composition analysis is shown in Table 2.

Table 2. Chemical composition of MNB in the adjustment period, % Dry Matter
Treatment	Protein	Fat	Fiber	Ash	Nitrogen Free Extract
SG50	15.3	0.8	14.9	43.3	25.6
SG45	13.9	0.9	17.6	40.1	27.6
SG40	10.7	0.6	12.9	31.6	44.2
SG35	10.3	0.7	14.0	27.7	47.3
Average ± SD	12.5±2.2	0.6±0.3	14.9±1.9	35.6±7.3	36.3±11.3

Table 4. Ingredients used in the MNB in the experimental period, %
Ingredients	SG50	SG45	SG40	SG35
Molasses	0	5	10	15
Stenocereus griseus L.	50	45	40	35
Urea	5	5	5	5
Common salt	5	5	5	5
Mineral mixture	2	2	2	2
Lime	7.5	7.5	7.5	7.5
Cement	7.5	7.5	7.5	7.5
Corn stubble	23	23	23	23

This was reflected in a greater amount of crude protein (32.5 ± 3.1%) and ash (42.6 ± 2.4) (Table 5).

Table 5. Chemical composition of MNB in the experimental period, % Dry Matter
Treatment	Protein	Fat	Fiber	Ash	Nitrogen Free Extract
SG50	36.1	0.8	12.4	44.8	5.9
SG45	34.1	0.9	12.7	42.7	9.6
SG40	30.8	0.8	10.8	43.7	13.8
SG35	29.2	0.5	12.2	39.3	18.8
Average ± SD	32.5±3.1	0.78±0.2	12.0±0.8	42.6±2.4	12.0±5.5

Even with 5% levels of urea, consumption of MNB did not cause any metabolic symptoms. Several authors have proposed amounts greater than 10% of urea in MNB (Bui et al 1995, Waliszewki and Pardi 1994, Robleto et al 1992), without negative effects on livestock.

Consumption, weight gain and body condition

The consumption of MNB by the goats in the adaptation period ranged from 10 to 30 g in the first week, stabilizing afterwards at 20 g/day. The results of the adaptation period convinced farmers that goats may consume ingredients like lime and cement without presenting physiological problems. This marked the guideline for designing the composition of MNB in the experimental period, rising levels of lime, cement and urea, without reducing sugar cane molasses (Table 4).

During the experimental period MNB consumption levels in SG50 and SG45 were statistically similar (P> 0.05). SG40 had a higher consumption (69.9 g / day) and greater weight gain (11.0 g / day), statistically similar to SG35 (P> 0.05) (Table 6).

Table 6. Consumption of MNB, weight gain (g / day), cost and changes in body condition
Treatment	SG50	SG45	SG40	SG35	CTL
No. of animals	5	5	5	5	5
No. of days	75	75	75	75	75
Average initial weight	19.5	19.8	19.2	22.0	19.5
Average final weight	20.1	20.3	24.4	22.0	19.5
Consumption	42^b	41.7^b	69.9^a	57.7^ab	0
Average increase/animal	8.3^a	0.6^b	11^a	9.3^a	0^b
Cost $/day*	0.08	0.08	0.13	0.11	0
Change in BC**	1	0.5	1	1	-0.3
* $ 1.00 = 0.10 USD at time of study Body condition ** Different letters in the same column indicate significant differences (P <0.05)

However, overall MNB consumption was lower than in previous studies (Ben Salem and Nefzaoui 2003, Garcia and Restrepo 1995) which reported 100g/day for goats and sheep. Low consumption of MNB may be due to a number of factors among which palatability and storage time are emphasized, which in this case was 8 months. Another factor that must be taken into account is the availability of drinking water. As MNB are high in NPN and salts, it is essential that the animals have free access to water in the places where they are consumed (García and Restrepo 1995). In this case the places of natural water storage are located 3 km away from the pens along the grazing routes, which might have affected consumption. A way to improve water consumption could be the storage of rain water to be used in dry season or to provide tap water.

With respect to SG45, weight gain was significantly lower than SG50 with similar consumptions, which can be explained in terms of the management of the participating farmer, who decided to locate the experimental unit outside the farm, which caused that the grazing of these animals did not follow the usual route of the herd, being less than the normal schedule of eight hours/day, so forage consumption was itself reduced. Other factors that influenced consumption in all treatments in this study were cultural issues in the region, full-day locking of animals for collective community activities, religious festivals and agricultural tasks.

It is necessary to assess how difficult it is to provide a diet with the necessary nutrients needed for maintenance and production (NRC 1981) especially in local (creole) goats when their management is extensive. This is also influenced by the botanical composition of trees and shrubs forage availability, management, physiological state and age, amongst other factors (Aguilera 2001). Goats are animals adapted to conditions of heterogeneous vegetation of native grasses, trees and shrubs in which they select their food, and absorb better the nutrients even under difficult environmental conditions (Arbiza and De Lucas 2000, Pérez 1998).

Weight gain in all treatments was low compared with the one reported by Habib (2007), of 32.6 g / day, versus 21.6 g / day in control animals on pasture. Since the cited study was conducted with an abundance of grasses and shrubs, the difference can be attributed to the fact that goats tend to select forage with high protein content. The author also reports a more active grazing and a greater water consumption in the animals supplemented with MNB.

As for costs, SG40 was the most expensive with $ 0.13/goat/day (Table 5). Nevertheless, it proved viable from the perspective of massive application in local goat production units, since the cost of one kg of commercial concentrate for goats at the time of study was $ 3.00 with an average of 18% crude protein, compared with $ 1.90 per kilogram of MNB.

During the experimental stage, the goats had free access to three legume species of shrubs that produce leaves during the severe drought: Prosopis laevigata, Acacia farnesiana, Acacia milibekii and to Quercus sp. For the control treatment, the deficiency of the forage and supplementation during the drought was reflected in no weight gain, although according to the farmers, animals usually lose weight during this time.

At the beginning of the experiment, the animals presented an average body condition of 1. In the case of CTL, it decreased by 0.3 points, and some animals lost weight, possibly due to the low nutritional value of highly lignified forage shrubs. Body condition in animals that received MNB improved in one point in the case of SG50, SG40 and SG35, probably due to the addition of energy from Stenocereus griseus and molasses, in addition to the NPN. On the other hand, body condition in SG45 increased only by 0.5 points, probably due to the management conditions, as previously explained. Overall, the animals supplemented with MNB presented better appearance, size, weight and body mass according to the scale of Catton and Petrie (2002).

Participatory evaluation

Three quarters of the surveyed farmers said that MNB can prevent weight loss in goats in the dry season, 17% think that they are possibly effective and 8% have doubts about their effect. As for the results observed in animals, 59% felt that MNB improved weight gain, 33% felt that they improved body condition and 8% expect a positive response when using them in the future in their herds. Many farmers visited the enclosures where goats consumed the MNB, with positive feedback on their use, which was reflected in the interviews. 100% of respondents would recommend the use of MNB in future droughts.

For the elaboration of new MNB in the future, 75% of interviewed farmers recommended the use of Stenocereus stellatus and Escontria chiotilla as widely available cacti fruits, and 25% recommended using dry pods of Acacia cimbispina Sprague, Acacia farnesiana and Prosopis Laevigata, foliage of wild shrubs and native grasses, besides the fruit of Stenocereus griseus .

Conclusions

Acknowledgments

The authors thank the community of Cosoltepec for having allowed them to work together, and most especially to the farmers that participated in the experiment, contributing their work, time and animals. To the Universidad Autónoma Metropolitana - Iztapalapa for the support and the facilities provided for the accomplishment of the project. Ladislao Arias received a scholarship from the PROMEP Program of the Ministry of Public Education.

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Table 3. Proximal analysis of Stenocereus griseus ( % of dry matter)
Proteína	Grasa	Fibra cruda	Cenizas	ELN
8.5	5.3	7.5	7.2	71.5