R.G. Ramírez

Feed resources and feeding techniques of small ruminants under extensive management conditions

Abstract Studies are discussed of the nutritional ecology of small ruminants under extensive conditions in northeastern Mexico. Spanish range goats selected greater amounts of foliage from shrubs (browse) than forbs and grasses throughout the year. Apparently high levels of the shrub Acacia rigidula (blackbrush) in the diets might have negatively influenced nutrient intake of goats. However, levels of crude protein and minerals in the annual diet were sufficient to meet adult goat requirements. Botanical composition of monthly diets of Pelibuey×Rambouillet range sheep grazing in a buffelgrass ( Cenchrus ciliaris ) pasture affected nutrient intake. In those months when level of browse increased in diets, the nutrient intakes increased. Native shrubs growing mixed with buffelgrass in pastures were important diet components for grazing sheep, especially during Fall and Winter. Browse during spring and summer provided adequate levels for sheep production of macro and trace elements, except for Cu which was deficient in most months. Browse also contributed a major percentage to the annual diets of white-tailed deer ( Odocoileus virginianus , texanus) in northeastern Mexico. Even though browse provided food and cover for deer, high levels of shrubs negatively influenced the digestibility of their monthly simulated diets. In addition, P concentrations were very low, and high levels of digestion of forb plants in the digestive tract of deer may underestimate the composition of forbs in feces.

Protein, lignin and mineral contents and in situ dry matter digestibility of native Mexican grasses consumed by range goats

Abstract Native grasses from northeastern Mexico, such as Aristida spp., Bouteloua gracilis (Thurb), Cenchrus incertus (M.A. Curtis), Hilaria berlangeri (Steud. Nash), Panicum hallii (Varsey), Setaria macrostachya (H.B.K.), and Cenchrus ciliaris (L.), an introduced grass, that are consumed by range goats were evaluated to estimate seasonal CP, lignin, Ca, P, K, Mg, Na, Cu, Fe, Zn, Mn contents, and the rate and extent of DM digestion. The in situ nylon bag technique was used to estimate effective digestibility/degradability of DM (EDDM). Potential mineral intake by an adult range goat consuming these grasses was also estimated. The CP content in all grasses was significantly different between seasons. P. hallii had high annual mean CP contents (12%) and Aristida spp. (6%) was low. The native grasses B. gracilis (9%, annual mean), S. macrostachya (10%) and C. incertus (8%) had CP values comparable to the introduced grass C. ciliaris (9%). Lignin contents in all grasses were also significantly different between seasons. Aristida spp. had high annual means (10%) and H. berlangeri was low (6%). With the exception of H. berlangeri , all grasses had higher lignin contents (annual means) than C. ciliaris (6%). The EDDM in all grasses was significantly different between seasons. C. incertus (45%, annual mean) had the highest EDDM, while Aristida spp. (26%) was lowest. During spring and autumn, EDDM in all grasses was higher than in the other seasons. P. hallii , H. berlangeri and C. incertus had comparable EDDM values to C. ciliaris (40%) in all seasons. It was estimated that an adult range goat consuming the studied grasses, could eat sufficient amounts of Ca, Fe, and K (except for K from Aristida spp. in winter and summer), but of Na, Zn and Mn only in spring and autumn, and of Cu only in autumn. The P and Mg contents were marginally deficient in most grasses and in all seasons. The native grasses P. hallii , S. macrostachya, B. gracilis can be considered valuable grasses for goats on the range, because of their relatively high CP contents, and C. incertus, P. hallii and H. berlangeri because of their relatively high EDDM values, comparable to C. ciliaris . However, range goats consuming these grasses need to be supplemented with P and Mg in all seasons, with Na, Zn and Mn in winter and summer, and Cu in winter, spring and summer seasons.

Ruminal digestion characteristics and effective degradability of cell wall of browse species from northeastern Mexico

Foliage from 15 shrub species was used to estimate the extent and rate of cell wall (CW) degradation in the rumen of fistulated Pelibuey sheep. Branches from the browse species: Acacia berlandieri, Acacia farnesiana, Acacia greggii, Acacia rigidula, Celtis pallida, Cercidium macrum, Condalia obovata, Cordia boisieri, Desmanthus virgathus, Leucaena leucocephala, Leucophyllum texanum, Opuntia lindehimieri, Porlieria angustifolia, Prosopis glandulosa, and Ziziphus obtusifolia, were collected during the spring of 1993 in Marin, County, Nuevo Leon, Mexico. Medicago sativa hay was used for comparison. Twelve ruminally cannulated male sheep (45 kg BW) were used (four sheep per plant) to incubate nylon bags (5 10 cm and 53 mm pore size); containing 4 g of ground material (1 mm screen) of each plant. Bags were incubated at 0, 4, 8, 12, 24 and 48 h. The rate of CW degradation (c, %) was highest (P < 0.001) in O. lindehimieri (9.8) and lowest in A. rigidula (2.8). Only O. lindehimieri and C. pallida (8.5) had higher CW degradation rates than M. sativa (7.1). Effective degradability of CW (EDCW), at outflow rates of 2%, 5% and 8% h ˇ1 values were higher in C. pallida (74.3, 62.9 and 56.6), C. obovata (54.5, 45.8 and 39.7), L. leucocephala (54.7, 45.1 and 39.8) and O. lindehimieri (67.8, 56.6 and 50.6) than in M. sativa (54.1, 44.9 and 39.5). High levels of lignin and condensed tannins affected the EDCW in some plants. Species such as C. pallida, C. obovata, L. Leucocephala and O. lindehimieri may be considered as good available forages for grazing ruminants in northern Mexico. # 2000 Elsevier Science B.V. All rights reserved.

Influence of Zilpaterol Hydrochloride on Growth and Carcass Characteristics of Pelibuey Lambs

Abstract Salinas-Chavira, J., Ramirez, R.G., Domínguez-Muñoz, M., Palomo-Cruz, R. and López-Acuña, V.H. 2004. Influence of zilpaterol hydrochloride on growth and. carcass characteristics of lambs. J. Appl. Anim. Res., 26: 13–16. To evaluate the effect of different doses of the feed additive β-agonist, zilpaterol hydrochloride (ZH) on performance and carcass characteristics of lambs, twelve intact male Pelibuey lambs (28.7±2.7 kg) were kept in individual pens and randomly assigned to three treatment (T) diets (four lambs per diet); lambs on T1 were fed the diet without additive, on T2 and T3 were fed the same diet and 4.35 and 6.0 fig ZH/g DM, respectively, for a second feeding trial. Lambs on T2 and T3 had the same (P<0.05) daily dry matter intake (1460.0 and 1375.0 g, respectively), average daily gain (365.0 and 347.0 g) and feed efficiency (4.0 and 4.0, respectively); however, both were significantly higher than those lambs on T1 (1175.0 g, 140.0g and 9.0, respectively). All lambs deposited the same (>0.05) subcutaneous fat. Lambs on T1 and T2 had similar (P>0.05) Longissimus dorsi area (9.8 and 11.2 cm2, respectively), but both were lower (P<0.05) than lambs on T3 (14.2 cm2). It is concluded that addition of ZH to a high concentrate diet fed to Pelibuey lambs showed improved performance.

Seasonal variation of macro and trace mineral contents in 14 browse species that grow in northeastern Mexico

Leaves and twigs from shrub species consumed by range goats: Acacia berlandieri, Acacia farnesiana, Acacia greggii, Acacia rigidula, Celtis pallida, Cercidium macrum, Condalia obovata, Cordia boissieri, Desmanthus virgathus, Leucaena leucocephala, Leucophyllum texanum, Opuntia lindehimieri, Porlieria angustifolia, Prosopis glandulosa, and Ziziphus obtusifolia were evaluated for comparative seasonal contents of Ca, P, Mg K, Zn, Mn, Cu and Fe. Plants were collected in summer (September 12, 1992), fall (November 20, 1992), winter (February 20, 1993) and spring (May 22, 1993) in Marín, County, Nuevo Leon, Mexico. During spring and summer mineral concentrations were higher in general. Only Ca, Mg, K, and Fe were in substantial amounts in all seasons to meet adult goat requirements. With the exception of spring, shrubs had extremely low P concentrations. Manganese, Cu and Zn in most plants had low marginal levels to meet adult goat requirements. Moreover, potential intake of P, Mn, Cu and Zn in shrub species by goats weighing 50kg BW consuming 2.0kg per day DM was low. However, plants such as D. virgathus, L. texanum, P. glandulosa, L. leucocephala and C. macrum can be considered prominent components in diets of range goats because of their high mineral concentrations. It appears that ration formulations for range goats in northeastern Mexico should include P, Mn, Cu and Zn in all seasons of the year.

White-tailed deer food habits in northeastern Mexico

Abstract Microhistological analysis of feces was used to estimate the selection of white-tailed deer ( Odocoileus virginianus , Tex.) in the state of Nuevo Leon in northeastern Mexico. Browse was the main component of deer diets (94% annual mean). Major species were blackbrush acacia ( Acacia rigidula Benth), guajillo ( Acacia berlandieri Benth) soapbrush ( Porlieria angustifolia Englem), cenizo ( Leucophyllum texanus Benth), huisache ( Acacia farnesiana L), popotillo ( Ephedra aspera Englem), palo verde ( Cercidium macrum I.M. Johnst) and honey mesquite ( Prosopis glandulosa Torr). These species represented about 82% the total plant composition of deer diets on an annual basis. Forbs were numerous (23 species in deer diets), but represented only about 5% of the total annual diet. Major forbs in deer diets were Hibiscus spp., Zephyranthes arenicola Hansel, Agrythamnia neomexicana Muell and Dyssodia acerosa DC. Grasses were selected by deer in very low amounts; buffelgrass ( Cenchrus ciliaris L.) was the major grass in the annual diets of deer. Because of the nature of deer diets, it is concluded that browse should be considered an important part of the deer habitat, and that those shrub species that are used by deer for food and refuge should be preserved.

Preference Indices for Forage Species Grazed by Spanish Goats on a Semiarid Shrubland in México

Abstract Ramirez, R. G., Sauceda, J. G., Narro, J. A. and Aranda, J. 1993. Preference indices for forage species grazed by Spanish goats on a semiarid shrubland in Mexico. J. Appl. Anim. Res., 3: 55–66. Botanical composition of diets of Spanish goats was studied on the Facultad de Agronomia, V. A N. L. Experimental Station with the objectives to determine monthly differences in preference indices of forage species grazed by Spanish goats on a blackbrush (Acacia rigidula) dominated shrubland. From June, 1988 to May, 1989, four esophageally fistulated mature goats were used to collect fistula extrusa samples. Botanical composition of the grazed area (25 ha) determined on 25 permanent line transects (10 m long), was 77, 15 and 8% shrubs, forbs and grasses, respectively. Contribution of shrubs, forbs and grasses to the annual diets averaged 83.4, 10.3 and 6.4%, respectively. Major shrubs in the annual diets were blackbrush (54. cenizo (Leucophyllum texanum) (16.7%), palo verde (Cercidium macrum) (3.8%), hackb...

Nutrient and mineral profile of white-tailed deer (Odocoileus virginianus, texanus) diets in northeastern Mexico

Abstract The study was conducted to estimate and to compare the monthly variation of nutrient content of diets of deer. During 1989, samples of plant species were collected and pooled, according to the botanical composition of feces to simulate the monthly diet of deer. Collections were carried out in four ranches (about 12000 ha) located in the state of Nuevo Leon. Two diets in each ranch were evaluated for CP, neutral detergent fiber (NDF), acid detergent fiber (ADF), insoluble nitrogen in acid detergent fibre (INADF), in vitro dry matter digestibility (IVDMD), macro and trace minerals. Deer consumed diets with a high content of browse species (annual mean 94.2%). Forbs represented 5.2% and grasses 0.6% of the total composition. The crude protein (CP) in diets varied ( P Acacia rigidula (about 50.0%) which had high levels of condensed tannins (about 15.0%) may negatively influence the in vitro digestion of DM. Calcium, Mg, Na and K concentrations in deer diets were in adequate amounts to satisfy ruminant requirements. Phosphorus levels in diets were extremely low during all months. Conversely, higher concentrations of P in feces may indicate that deer had consumed more forbs than those determined by microhistology in feces. Although deer requirements of trace elements are unknown, they selected diets with concentrations of Fe, Mn and Cu to cover beef cattle requirements. However, Zn was the most limiting trace element appearing at marginal levels in diets during 6 months (summer and fall). It is recommended to managers and owners to open forest canopy in the range to allow an increase of forbs and native grass diversity and density with its associated increased nutritional value.

Forage utilization from native shrubs Acacia rigidula and Acacia farnesiana by goats and sheep

Two trials, (in vivo and in situ) were conducted to evaluate the influence of shrub leaves on digestion and N retention by goats and ruminal digestion by sheep. In trial one, 12 male castrated Spanish goats (32.5 ± 2.1 kg LW) were housed in metabolism stalls and randomly assigned to three diets (four goats per treatment): (1) 23% alfalfa hay (Medicago sativa) plus bean straw (Phaseolus vulgaris); (2) 25% blackbrush acacia (Acacia rigidula) plus 75% bean straw and (3) 20% huisache (Acacia farnesiana) plus 80% bean straw. Nutrient intake of goats was similar (P > 0.05) among diets. Digestibility of DM was similar (P > 0.05) among goats; however, CP digestibility was higher (P 0.05). In addition, goats retained similar amount of N (P > 0.05) among diets. Leaves from the shrubs were digested poorly in the rumen of sheep, compared with the alfalfa hay. Tannins in shrubs may have adverse influence in situ on digestibility of CP and NDF. Moreover, condensed tannins may have reduced goat digestion of CP and NDF and its fractions. However, native shrubs may have potential as an economical supplementary feed for goats because N utilization and DM intake levels were similar for goats given alfalfa hay and native shrub diets.

Forage selection by range sheep on a buffelgrass (Cenchrus ciliaris) pasture

During 1989, six esophageally fistulated male lambs (Pelibuey × Rambouillet), weighing 38.8 ± 1.8 kg, were used to collect monthly extrusa on a buffelgrass (Cenchrus ciliaris) dominated pasture. Sampling periods (January through December) lasted 9 days (5 days adaptation followed by 4 days for extrusa collection). Monthly extrusa were separated in two portions; one was subjected to micro histological analysis and the other to chemical analysis. Botanical composition of the study area (10 ha) was measured monthly. Preference indices of lambs for forage species were also determined. Vegetation of the covered area was composed of 71.7%, 27.7% and 0.6% grasses, shrubs and forbs, respectively. Plant contribution of grasses, shrubs and forbs to the annual diets averaged 85.2%, 14.0% and 0.8%, respectively. Major shrubs in diets were soap brush (Porlieria angustifolia), black brush (Acacia rigidula), palo verde (Cercidium macrum) and cenizo (Leucophyllum texanum). Soap brush was the main preferred shrub by lambs throughout the year. Preference indices for forbs were inconsistent. Buffelgrass was preferred by lambs during all months, comprising 85.1% of the annual diets. This study suggested that the presence of shrubs and forbs in diets of lambs increased the levels of crude protein and in vitro organic matter digestibility. Even though cell wall constituents (neutral detergent fiber and acid detergent fiber) in forage selected by lambs were variable (P < 0.05) among months, percentages of these fractions were in agreement with published values. Mixed palatable native shrubs and forbs with buffelgrass in the pasture could improve the nutritive value of the dry matter available in the forage.