Nutritional strategies, performance, digestibility, and carcass traits of Santa Ines and Rabo Largo breeds in a tropical climate.

The aim of this study was to compare the performance, intake, digestibility, ruminal parameters, carcass traits, and the yield of commercial cuts of Santa Ines (SI) and Rabo Largo (RL) breeds fed diets with high or low roughage-to-concentrate ratio (R:C) under a tropical climate. Twenty lambs from each breed were individually housed in covered pens and fed the experimental diets for 58 days. The diets were formulated to meet the growth requirements of lambs with a roughage-to-concentrate ratio of 70:30 and 30:70. Significant interactions of breed × diet for nutrient intake were observed (P < 0.05), with SI lambs fed low R:C diet showing higher intake of dry matter, organic matter, crude protein, and total carbohydrates compared to RL lambs fed the same diet. SI lambs fed high R:C diet had higher intake of neutral detergent fiber than RL lambs (P < 0.05). SI lambs displayed better average daily gain and feed efficiency, regardless of diet (P < 0.05). Carcass traits and gastrointestinal components were influenced by breed and diet (P < 0.05). SI lambs fed low R:C diet showed higher subcutaneous fat thickness and better carcass finishing compared to RL lambs (P < 0.05). SI breed lambs exhibited better growth performance, carcass traits, and gastrointestinal characteristics, even when fed diets with a high roughage-to-concentrate ratio.

Effects of cottonseed hull on intake, digestibility, nitrogen balance, blood metabolites and ingestive behaviour of rams.

The aim of this study was to determine the effect of cottonseed hull (CH) in the diets of rams on intake, digestibility, nitrogen balance, ingestive behaviour, and blood metabolites. Twenty males, uncastrated with an average body weight of 29.08 ± 4.18 kg, were distributed in a completely randomized design with four treatment diets and five replicates. The diet contained a forage to concentrate ratio of 50 : 50 (ground corn, soybean meal, corn silage, and CH), and the experimental treatments were inclusion of 0, 10, 20, and 30% CH (dry matter basis). Inclusion of CH linearly increased water intake, effective intake of ethereal extract and non-fibrous carbohydrates, and crude protein digestibility. Dry matter (DM) and neutral detergent fiber (NDF) digestibility, nitrogen faecal losses, and nitrogen balance reduced linearly with CH inclusion in the diet. Inclusion of CH in rams' diet reduces intake, nutrient digestibility, and intake and rumination efficiencies. Thus, it is not recommended to add this by-product to the diet of high-performance rams, but for nurture that does not aim at high performance, inclusion of up to 5% of this by-product is recommended.

Nutritional effects and feeding behavior in ewes fed with biscuit bran and cashew nut bran, with different energy levels.

This research evaluated the effects of biscuit bran and cashew nut bran as energy source and additional energy level on intake, digestibility, feeding behavior, energy partitioning, N balance, and blood parameters on ewes. Twenty Morada Nova cull ewes breed (average age of 3 years old and initial body weight of 30.1 ± 3.56 kg) were distributed in a completely randomized design in a 2 × 2 factorial scheme of two energy sources (biscuit bran vs. cashew nut bran) and two levels of energy above 10% and 25% of the recommended energy requirements. The inclusion of cashew nut bran above 10% of the recommended energy promoted a lower crude protein (CP) and ethereal extract intake (P < 0.01) than cashew nut bran above 25% of the recommended energy. The interaction between energy source × energy level did not affect digestibility and energy partition on ewes (P > 0.05). The diet containing cashew nut bran above 10% of the recommended energy presented lower metabolizable energy intake and energy balance (P < 0.05). Regarding N balance, the cashew nut bran diet above 10% of the recommended energy decreased Nintake (P = 0.01), Nabsorbed (P < 0.01), and Nbalance (P = 0.04). Partial replacement of corn with the byproduct biscuit bran or cashew nut bran is a possible nutritional strategy. Ewes fed with 210 g/kg of biscuit bran presented greater CP intake and improvement of the protein use with the reduction of plasma levels of urea.

Changes on the physicochemical and fatty acid profile of meat induced by inclusion of biscuit bran in lamb diet.

The animal feed science is in constant search for new products that bring economic return, without harming the quality of the final product. This study aimed to evaluate the effect of increasing levels of substitution of corn by biscuit bran in lamb diet upon the fatty acid profile of its meat and its physicochemical and sensory characteristics. Twenty-four male lambs divided in four treatments were used. The treatments consisted in increasing levels (0, 15, 30, and 45%) of substitution of corn by biscuit bran in lamb diet. The significance of the treatments was determined by ANOVA and the adjusted means were compared by Tukey test at 5%. The effects were determined by linear and quadratic responses. The use of up to 45% biscuit bran sweet type did not modify the physical and sensory characteristics of meat, just as it did not affect nutrient and dry matter intakes and animal performance. A replacement of 45%, reduces the cholesterol (P = 0.03) and the total content of saturated fatty acid (P = 0.002), not modifying other physicochemical characteristics. The replacement of corn by biscuit bran sweet type in the feeding represents an alternative nutritional strategy for sheep meat production with desirable organoleptic and quality characteristics.

Feeding restriction in the pre and postpartum period of hair ewes raised in the semi-arid region: implications on performance and carcass traits of the progeny.

Feed restriction (FR) occurs commonly in sheep production systems in the Brazilian semi-arid region and can cause physiological changes in the progeny. We assessed the effects of the FR pre and postnatal on the performance and carcass traits of Morada Nova lambs. Twenty-four lambs born from a group of 68 ewes were distributed in three treatments of 8 replicates as follows: ewes fed ad libitum pre and postnatal (AL-AL); postnatal restriction (POSTN-R): included lambs born from ewes fed ad libitum in the last third of pregnancy with FR postnatal; and prenatal feeding restriction (PREN-AL): comprised lambs born from ewes subjected to FR in the last third of pregnancy but ad libitum postnatal. Slaughter body weight (20.96 kg); total weight gain (11.34 kg); average daily weight (0.096 kg); fasting carcass weight (19.45); hot carcass weight (9.33 kg); and cold carcass weight (9.11 kg) were smaller (P < 0.05) in POSTN-R but similar between AL-AL and PREN-AL. Rib (0.47 kg), shoulder (0.85 kg), loin (0.50 kg), and chest-flank (0.97 kg) had lower weight in lambs under POSTN-R (P < 0.05). The treatments did not affect the tissue composition of the 12th rib. The non-carcass components and carcass traits are the variables that best discriminate animals under FR plans. The postpartum FR in native lambs has an impact on the performance and carcass weight of the progeny, unlike lambs submitted to prepartum FR, which demonstrates the adaptation to intrauterine nutritional deficiency in Morada Nova ewes to produce lambs with heavy carcasses in regions semi-arid.

Effect of distance and daily periods on heat-stressed pigs and pre-slaughter losses in a semiarid region.

Effective planning animal transport is essential to safeguard animal welfare and reduce production losses. Environmental conditions, specifically extreme temperatures in combination with ranges of relative humidity are highlighted as one of the main risk factors for production losses during transport (e.g., fatalities). The majority of research evaluating both welfare and production impacts of pig transport have been primarily undertaken in Europe and North America, which cover a relatively limited range of distinct climates (e.g., temperate, sub-arctic, etc.). As a result, research on pig transport in semi-arid conditions is lacking. In this study, we evaluated the effects of both distance (short, 30 km; and long, 170 km) and transport daily periods (morning, (05:00-11:00); afternoon (12:00-17:00); and night, (23:00-04:00)) on the preslaughter losses and heat stress of pigs in commercial transport in a semiarid region. Across 19 journeys of standard slaughter-weight pig loads (124.0 ± 2.8 kg), 684 focal animals (36 per journey) were evaluated. For each journey, the load's thermal profile (THIadj and enthalpy) and physiological responses of individual pigs were recorded. On arrival at designated slaughterhouses, the percentage pig of non-ambulatory non-injured (NANI), non-ambulatory injured (NAI), death on arrival (DOA), and total losses were recorded. Short journeys in the afternoon were shown to be more detrimental to the thermal comfort of pigs, with higher rectal temperatures recorded. The highest percentage of total losses and DOA occurred in afternoon journeys, irrespective of distance, followed by the morning, with the lowest losses observed in pigs transported at night. Additionally, total losses and DOA were further exacerbated by journey distance, with higher rates observed in short journeys. Higher percentage averages of NANI and NAI were observed in shorter journeys, but daily periods effects were only observed for NANI. These results further demonstrate the welfare and production loss risks associated with journey distance and time of day (representing varying environmental conditions) during road transport of pigs, whilst providing novel data in semiarid conditions. Careful and effective planning for pig transportation is essential to minimize heat stress and production losses. Consideration of the thermal environment on the day of travel, as well as providing flexibility to adjust travel times (e.g., early morning or evening), should help to mitigate risks of heat stress and production losses during pig transport.

Effects of Dietary Babassu Oil or Buriti Oil on Nutrient Intake and Total Tract Digestibility, and Abomasal Digesta Fatty Acid Profile of Lambs.

Our current understanding of the effect of medium-chain FA (MCFA) rich vegetable oils on ruminant nutrition is limited. We assessed the effects of babassu or buriti oil addition to the diet of lambs on intake, nutrient digestibility, FA profile of abomasal digesta content and biohydrogenation (BH) patterns in digestion. The experimental diets were defined by the addition of babassu oil or buriti oil to the diet, as follows: (1) non-supplemented diet (CON); (2) 40 g/kg of babassu oil (BAO, rich in C12:0); and (3) 40 g/kg of buriti oil (BUO, rich in c9 18:1), on a dry matter (DM) basis. During the last five days of the feedlot, samples of orts and feces were individually collected to determine the nutrient and FA digestibility. At the end of the experiment, animals were slaughtered, and the abomasal digesta was collected, freeze-dried and used for FA determinations conducted by gas chromatography. The BAO diet decreased the DM (p = 0.014) and nutrient intake. The lambs fed BUO had the greatest FA intake, followed by the BAO and CON diets. However, BAO increased total FA digestibility, compared with CON, but did not differ from BUO. The BAO diet extensively changed the FA composition of abomasal digesta when compared with both the CON and BUO diets. The BAO diet also increased C12:0 and C14:0, the sum of PUFA and the BH intermediates FA, including the t-10-18:1 but decreased the C18:0 in abomasal digesta. The BUO addition had the greatest total-FA and C18:0 and the lowest biohydrogenation intermediate content in abomasal digesta. The BH was less complete with the BAO diet and a large increase in t10-18:1 and of t10-/t11-18:1 ratio was observed, which indicates the occurrence of t10 possibly shifted rumen BH pathways, probably as a response to bacterial membrane stress induced by the greater C12:0 concentration in the rumen.

Rumen fermentation and metabolic profile of rams fed with diets amended cottonseed cake.

The aim of the study was to evaluate the addition of increasing cottonseed cake contents in the diet. The diets were composed of corn silage (500 g kg-1) and concentrate feed (500 g kg-1) on a dry matter (DM) basis. The treatments consisted of the substitution of 0, 140, 280, and 420 g kg-1 soybean meal to cottonseed cake in the DM of concentrate feed. Four rams of the Santa Inês breed, average age of 12 months and average weight of 27.77 ± 3.87 kg, were distributed in a Latin square design (4 × 4) in a split-split-plot design, with diets in the plots and as subplots were 5 days of collection and the collection times. The results were subjected to analysis of variance and regression at 5% probability. The soybean meal substitution contents by cottonseed cake in the concentrate increased linearly the pH (P = 0.019). Ruminal ammonia-nitrogen concentration decreased linearly by 0.0137 mg dL-1 at each 10 g/kg of substitution and the time after feeding promoted the same effect (P < 0.001) decreased linearly by 0.6204 mg dL-1 at each hour after feeding. There was an increased linearly of 0.0116 mmol mL-1 at the concentration of propionic (P = 0.008) and a reduction of 0.0062 mmol mL-1 at the concentration of butyric (P = 0.009) with cottonseed cake content; however, the substitution did not influence the others short-chain fatty acids. Replacement of soybean meal with cottonseed cake in the sheep feed did not significantly alter the blood parameters, promoting minor changes in the ruminal parameters mainly in the ruminal ammonia-nitrogen without affecting the animal's health.

Fermentative profile, losses and chemical composition of silage soybean genotypes amended with sugarcane levels.

The experiment aimed to evaluate the fermentative and nutritional profile of the silage of four soybean plant genotypes (BRS 333 RR, Pampeanas: C50, C60, and C70) ensiled with levels of sugarcane (0, 25, 50, 75, and 100%). The experiments were conducted in a completely randomized design, in factorial scheme 4 × 5 (four soybean genotypes and five levels of sugarcane inclusion) with four replicates. Silages with 100% soybean plant presented the highest levels of butyric acid (P < 0.001) and ammoniacal nitrogen (P < 0.047); however, the intermediate addition of sugarcane contributed to lactic fermentation (P < 0.001). Besides, there was a quadratic effect (P < 0.05) for the recovery of dry matter, which ranged from 83.28 to 95.29%, with higher values observed for silage with the same proportions of soybean plant and sugarcane. It was verified that the crude protein content exhibited decreasing linear effects (P < 0.001), varying among 4.60 to 7.48% in the silages. It was concluded that the highest recovery of dry matter, the best fermentation profile, and the highest levels of crude protein and digestibility occurred in the inclusion between 25 and 50% of sugarcane in soybean silage, with the superiority of the C50 soybean genotype.

Digestive Potential of Soybean Agro-Industry Byproducts.

This study aimed to determine the protein and carbohydrate fractions as well as the in situ rumen degradability of Brachiaria decumbens silage (BDS) supplemented with soybean hulls. Five soybean hull inclusion levels were used: 0, 10, 20, 30, and 40% of the fresh matter of B. decumbens grass, distributed into a completely randomized design with five replications. The inclusion of soybean hulls caused a linear decrease (p < 0.001) in carbohydrate fractions A + B1 and a linear increase (p < 0.001) in carbohydrate fraction C. The percentage of non-protein nitrogen fraction increased linearly (p < 0.001), but the nitrogen fractions B1 + B2 and B3 presented a negative quadratic effect (p < 0.01) with soybean hull level and fraction C presented a linear decrease (p < 0.001). The dry matter (DM) degradability of soluble fraction (A) and the undigestible DM decreased linearly (p < 0.01) with the soybean hull level. The potentially degradable water-insoluble portion (DM fraction B) and degradability rate (c) of the DM fraction B increased linearly (p < 0.001) with soybean hull level. The crude protein (CP) fraction A presented a linear increase (p < 0.001) with soybean hull inclusion; however, soybean hull levels caused a linear decrease (p < 0.001) in the CP level of fraction B. The degradable insoluble fraction of NDF (D) of the silage increased linearly (p < 0.001) and the indigestible NDF fraction of the silage was linearly decreased with the soybean hull level (p < 0.001). The inclusion of intermediate levels (20-30%) of soybean hulls provided better protein and carbohydrate fractions and better quality of BDS.

Effects of the dietary inclusion of babassu oil or buriti oil on lamb performance, meat quality and fatty acid composition.

The effects of adding babassu oil (BAO) or buriti oil (BUO) to lamb diets, on performance, carcass characteristics, meat quality and fatty acid (FA) composition were evaluated. Feeding BAO reduced (P = .02) dry matter intake, kidney fat and dressing percentage, but did not change energy intake and performance. Meat pH, color, protein content and sensorial evaluation were not affected by diet. However, BUO increased (P = .02) intramuscular and subcutaneous fat contents, but decreased shear force. BAO increased (P < .05) trans-monounsaturated FA, total biohydrogenation intermediates (BHI) and the t10:t11 ratio, in meat and subcutaneous fat, but decreased total FA and cis-monounsaturated FA, did not change SFA, and increased (P = .04) PUFA in meat. BUO supplementation promoted the highest (P < .05) SFA and total FA content in subcutaneous fat but did not change PUFA. BAO can be used as an alternative energy source for growing lambs, but does not improve the meat FA composition.

Effects of supplementation with vegetable oils, including castor oil, on milk production of ewes and on growth of their lambs.

The objectives in this experiment were to compare the effects of castor oil, canola oil, or sunflower oil on lactation performance, milk composition, and milk fatty acid (FA) profile in Santa Inês ewes and on growth of lambs. Forty-four ewes (66.9 ± 4.7 kg of initial BW, mean ± SD) were penned individually with their lambs and used in a randomized complete block design with 11 blocks and four diets. The experimental diets were as follows: 1) basal diet without added oil (control), 2) 30 g FA/kg DM of canola oil (CAN), 3) 30 g FA/kg DM of sunflower oil (SUN), and 4) 30 g FA/kg DM of castor oil (CAS). The oils were added to a basal diet containing 50% of roughage. Once a week, from the 2nd to 8th wk of lactation, ewes were separated from their lambs, injected with oxytocin, and mechanically milked to empty the udder. After 3 h, using the same procedure, milk production was recorded, and milk was sampled for composition and FA profile determination. The growth of the lambs was monitored weekly. Ewes fed the control diet had greater (P < 0.05) dry matter intake (DMI) than those fed the oil-supplemented diets. No effect was observed on milk yield and on final BW of lambs. Milk fat and milk total solid concentrations were greater (P < 0.05) with the supply of CAS. Supplementation with CAN and SUN, but not with CAS, reduced (P < 0.05) the sum of FA with 14 or less carbon chains and increased (P < 0.05) the c9-18:1, 18:0 and most of the biohydrogenation intermediates, including the t10-18:1, t11-18:1, and c9,t11-18:2. All oil-supplemented diets reduced (P < 0.05) the content of 16:0 when compared with the control. Milk from ewes fed CAS presented only small proportion of 12-OH,c9-18:1 (0.31% of total FA) but much larger proportions of 12-OH-18:0 (1.58% of total FA) and particularly of 12-oxo-18:0 (2.95 % of total FA), which suggests that 12-OH,c9-18:1 was extensively metabolized in the rumen. Concluding, CAS increased milk fat and modified the milk FA composition by increasing the hydroxy- and oxo-FA. The potential health promoting proprieties and technological advantages of milk enriched with hydroxy- and oxo-FA are not know at present but deserve to be explored.

New insights on the metabolism of ricinoleic acid in ruminants.

Dairy goats were fed a total mixed ration with or without the inclusion of castor oil [40 g/kg of dry matter (DM)] to study the metabolism of ricinoleic acid (12-OH,cis-9-18:1). Ten goats, at 39.7 ± 4.0 d in milk, were individually penned and allocated at random to the 2 experimental diets. Goats were manually milked twice a day. Milk fatty acids (FA) were analyzed as methyl esters and hydroxyl groups were derivatized in trimethylsilyl ethers. Apart from ricinoleic acid, 6 FA were only detected in the milk of the castor oil group. Ricinoleic acid composed 0.3% of total FA in milk of the castor oil group, whereas the hydroxy-FA (8-OH-14:0, 10-OH-16:0, and 12-OH-18:0) and oxo-FA (8-oxo-14:0, 10-oxo-16:0, and 12-oxo-18:0) reached 7.5% of total FA in milk. We anticipate that these FA were derived from the metabolism of ricinoleic acid, although it was not clear if they were produced in the rumen or in the tissues. To confirm that, we conducted in vitro batch incubations repeated for 3 consecutive weeks with castor oil (40 g/kg of DM) and strained rumen fluid from 2 fistulated sheep. To examine the products formed over time, incubation tubes were stopped at 0, 6, 12, 24, 48, and 72 h. The results of the in vitro experiment showed that ricinoleic acid was metabolized in the rumen at a slow rate and the main products formed were 12-OH-18:0 and 12-oxo-18:0, by hydrogenation of the cis-9 double bond, followed by oxidation of the hydroxyl group, respectively. Our results suggest that the 12-OH-18:0 and 12-oxo-18:0 escape rumen and are further metabolized through partial ß-oxidation in ruminant tissues. We propose that the 10-OH-16:0 and 8-OH-14:0 found in goat milk of the castor oil group are successive products of the ß-oxidation of 12-OH-18:0, and the 10-oxo-16:0 and 8-oxo-14:0 are successive products of the 12-oxo-18:0 in tissues. Overall, our results indicate that ricinoleic acid is extensively metabolized in the rumen and tissues, producing mainly oxo- and hydroxy-FA that are further excreted in milk.

Intake, Nutrient Apparent Digestibility, and Ruminal Constituents of Crossbred Dorper × Santa Inês Sheep Fed Diets with Babassu Mesocarp Flour.

The aim of this study was to evaluate the effect on intake, apparent digestibility, and ruminal constituents of sheep in response to the addition of increasing levels of babassu mesocarp flour (BMF) to the diet. Twenty crossbred sheep (29.17 ± 2.23 kg) were used in a randomized complete block design. Lambs were confined for 21 days, with 16 days for diet adaptation and 5 days for data collection, in which they were fed an isonitrogenous diet (16.5 ± 0.2 CP, DM basis) containing 70% of concentrate and 30% (DM basis) of Tifton 85 hay. Increasing levels of BMF were 0, 10, 20, and 30% (DM basis). There was a quadratic effect (P < 0.05) on the DM intake, nutrients intake, and digestibility of CP and NFC. The digestibility of DM, OM, TC, and NDF decreased linearly, while EE digestibility increased linearly with increasing levels of BMF. The high NDF content presented in the chemical composition of the babassu mesocarp flour ranked the same as fibrous food, which can limit the inclusion in the diet of high production animals. So, babassu mesocarp flour is an alternative for energy source in lambs feed and can be added at levels up to 10%.

Desempenho produtivo de cabritos alimentados com glicerina bruta / Productive performance of goat kids fed of crude glycerin

Avaliou-se o desempenho produtivo de cabritos mestiços terminados em confinamento, alimentados com dietas contendo glicerina bruta (0, 4, 8 e 12% na MS). Vinte cabritos mestiços foram utilizados em blocos completos, casualizados com quatro tratamentos e cinco repetições, para determinação do ganho médio diário (GMD), consumo de matéria seca (CMS) e nutrientes (PB, FDN, EE) e comportamento ingestivo. Para o ensaio de digestibilidade, foram utilizados quatro caprinos alocados em delineamento em quadrado latino, para determinação da digestibilidade da MS e nutrientes (PB, FDN, EE). A adição de glicerina bruta não interferiu (P>0,05) no GMD e no CMS e demais nutrientes. O tempo de ingestão aumentou com o incremento de glicerina bruta nas dietas. Não houve diferença significativa (P>0,05) dos tratamentos sobre o tempo gasto na ruminação e digestibilidade da MS, PB e FDN, contudo, houve efeito quadrático para a digestibilidade do EE. Recomenda-se a inclusão em até 12% de glicerina bruta para cabritos em terminação, em situações de oscilação do preço do milho, sem alteração nos parâmetros produtivos avaliados.

This study was conducted to evaluate the productive performance of crossbred goats finished in feedlots fed diets containing increasing levels of crude glycerin (0, 4, 8 and 12%, DM basis). Twenty crossbred goat kids were used in a randomized complete block design with 4 treatments and 5 replications to determine average daily gain (ADG), dry matter intake (DMI) and nutrients (CP, NDF, EE) and ingestive behavior. For digestibility trial, four castrated male goats were used in a Latin Square Design to determine the DM and nutrients digestibility. Crude glycerin did not affect (P>0.05) the ADG, DMI and nutrients intake. Eating time increased linearly (P<0.05) with crude glycerin addition. Rumination time and dry matter and nutrients digestibility were unaffected by crude glycerin addition. However was a quadratic effect (P<0.05) to EE digestibility. It is recommended adding up to 12% crude glycerin to finishing kids, in situations of high price of corn, without changes in production parameters evaluated.

Impacto do pastejo no ecossistema caatinga / Impacto del pastoreo en el ecosistema caatinga / Impact of the grazing in the caatinga ecosystem

A compreensão da influência do pastejo animal sobre os atributos da vegetação da caatinga é de extrema importância, quando se pensa em uma atividade pecuária sustentável. O entendimento de aspectos relevantes como a retirada da cobertura vegetal pelos animais, principalmente no período seco, no qual a liteira torna-se a principal fonte de alimentos, o aspecto relacionado à ciclagem de nutrientes no solo e o efeito sobre suas propriedades físicas devem ser melhor elucidados. Não obstante, a retirada da caatinga, vegetação nativa nas regiões semiáridas do Nordeste, aliada a longos períodos e estiagem, provoca acentuada degradação física, química e biológica, deixando o solo totalmente descoberto e exposto por mais tempo às ações da temperatura e dos ventos, reduzindo, consequentemente, seu potencial produtivo, causando danos muitas vezes irreversíveis ao meio. A comunidade animal pode induzir alterações pelo tipo de pastejo, tipo de deposição das excretas e alteração na composição da vegetação, afetando o equilíbrio do ecossistema. Para manter esse potencial, é necessário o retorno da matéria orgânica, além do maior controle da sua retirada, por meio do manejo adequado dos animais, no tocante aos indicadores como pressão de pastejo e taxa de lotação, contribuindo certamente para a manutenção da diversidade biológica do ecossistema.

Understanding the influence of the animal grazing about the attributes of the vegetation of caatinga is very important when thinking about a sustainable livestock farming. The study of prominent aspects such as the retreat of vegetation by the animals, mainly in the dry period where to liteira becomes-itself to main spring of food, the aspect related to the nutrient cycling in soil and the effect about the physical properties of the even should be better explained. Nevertheless, the retreat of the caatinga, native vegetation in the Semi-arid regions of the Northeast, ally to long periods and dry spell, provokes accentuated biological, chemical, and physical degradation, leaving soil entirely discovered and displayed by longer to the actions of the temperature and of the winds, reducing, consequently, its productive potential, generally causing damage to the environment. The animal community can prompt alterations by the kind of grazing, kind of deposition of excrete and alteration in the composition of the vegetation, affecting the equilibrium of the ecosystem. To maintain that potential, it is necessary the return of the organic matter, beyond the most greatest control of its retreat by means of the adequate management of the animals when it comes to the indicators as grazing pressure and stockinAg rate, contributing correctly for the maintenance of the biological diversity of the ecosystem.

La comprensión de la influencia del pastoreo animal sobre los atributos de la vegetación de la caatinga es de extrema importancia cuando se piensa en una actividad pecuaria sustentable. El entendimiento de aspectos relevantes como la retirada del forraje vegetal por los animales, principalmente en el periodo de sequía, en el cual la leche se convierte en la principal fuente de alimentos, el aspecto relacionado al ciclo de nutrientes en el suelo y el efecto sobre sus propiedades físicas deben ser mejores elucidados. Sin embargo, la retirada de la caatinga, vegetación nativa en las regiones semiáridas del Nordeste, junto a largos períodos de estiaje provoca acentuada degradación física, química y biológica, dejando el suelo totalmente descubierto y expuesto por más tiempo a las acciones de la temperatura y de los vientos, reduciendo, consecuentemente, su potencial productivo, causando daños muchas veces irreversibles al medio. Los animales pueden inducir alteraciones por el tipo de pastoreo, de deposición de las excretas y alteración en la composición de la vegetación, afectando el equilibrio del ecosistema. Para mantener ese potencial, es necesario el retorno de la materia orgánica, además de mayor control de su retirada a través del manejo adecuado de los animales, con respecto a indicadores como la presión de pastoreo y la carga animal, contribuyendo sin duda para la manutención de la diversidad biológica del ecosistema.