S. W. Coleman

Profile of the bovine acute-phase response following an intravenous bolus-dose lipopolysaccharide challenge.

Our objective was to characterize further the acute-phase response following endotoxin (i.e. lipopolysaccharide; LPS) exposure in the bovine. Nine pure-bred Angus castrated males (i.e. steers; average body weight = 299 ± 5 kg) were used in a randomized complete block design in environmentally controlled chambers, set at thermoneutral level, to characterize the acute physiological, endocrine, immune, and acute-phase protein responses following an i.v. bolus administration of 2.5 μg of LPS/kg body weight. One day before administration of LPS, all steers were fitted with an indwelling jugular vein catheter for serial blood collection. Blood samples were collected at 30-min intervals from -2 h to 8 h relative to the LPS challenge (time 0), and serum was harvested and stored at -80 °C until analyzed for concentrations of cortisol, pro-inflammatory cytokines, and acute-phase proteins. Indicators of thermal status (i.e. rectal temperature, ruminal temperature, respiration rate, sweat rate, and skin temperatures) were measured at 30-min intervals from -1 h to 6 h relative to the challenge. Endotoxin exposure increased (P<0.05) serum concentrations of cortisol, tumor necrosis factor-α (TNF-α), interleukin 1-β (IL-1β), IL-6, interferon-γ (IFN-γ), and serum amyloid A. Respiration rate, rectal temperature, and rump skin temperature also were increased (P<0.05) following LPS administration. Endotoxin exposure dramatically decreased ear skin temperature (P = 0.002), but tended to increase (P<0.10) ruminal temperature, shoulder skin temperature, and shoulder sweat rate. Serum concentrations of acid soluble protein, α-acid glycoprotein, IL-4 and IL-2, and rump sweat rate were not altered (P>0.24) by the challenge. To our knowledge, this report is the most complete characterization of the bovine acute-phase response to a bolus-dose endotoxin challenge conducted under thermoneutral conditions and should provide foundation data for future research.

Evaluation of physiological and blood serum differences in heat-tolerant (Romosinuano) and heat-susceptible (Angus) Bos taurus cattle during controlled heat challenge.

A study was performed to evaluate differences in thermoregulatory ability of 2 Bos taurus breeds with known differences in heat tolerance. Nine Angus (AG; 304 +/- 7 kg of BW) and 9 Romosinuano (RO; 285 +/- 7.5 kg of BW) steers were transported to the Brody Environmental Center at the University of Missouri. Steers were housed for 18 d at thermoneutrality (TN; 21 degrees C) before initiation of heat stress (HS), which consisted of daily cyclic air temperature (26 degrees C, night; 36 degrees C, day) for 14 d. Rectal temperature and respiration rate were measured 6 times daily throughout the study. Sweat rates at shaved skin sites were recorded on specific days. Blood samples were taken once per week. Angus steers maintained rectal temperature 0.5 degrees C greater than RO at TN (P < 0.001). Likewise, respiration and sweat rates were greater (P < 0.001) in AG than RO at TN (P < 0.05). Rectal temperature increased during HS for both breeds with AG maintaining greater temperatures (P < 0.001). Both breeds increased respiration rate during HS, with AG steers exhibiting the greater rate (P < 0.001). Sweat rate increased more than 4-fold during HS (P < 0.001), followed by reduction after 7 d. Even after HS acclimation, AG exhibited the greater sweat rate (P < 0.001). Breed differences for serum leptin, creatinine, and cholesterol were found throughout the study with AG being greater than RO. Although there were no breed differences (P = 0.21) at TN, only AG steers exhibited a HS-induced increase (P < 0.05) in prolactin, creatinine, and cholesterol concentrations to suggest that an increase in rectal temperature is required for this effect. Use of rectal temperature along with endocrine markers, such as prolactin, may aid in the identification of B. taurus sensitivity to heat.

Determination of Forage Chemical Composition Using Remote Sensing

Abstract Traditional forage nutrient analysis from bench-top near-infrared spectroscopy (NIRS) or common laboratory chemical procedures provides accurate, point-based information, but often does not provide it in a timely way to allow changes in forage or animal management. The objective of this study is to determine the feasibility of estimating concentrations of nitrogen, neutral detergent fiber (NDF), and acid detergent fiber (ADF) of live, standing forages using a hand-held hyperspectral spectroradiometer (radiometer), and to compare these estimates to values determined via NIRS and laboratory chemical methods. Calibration equations were developed from canopy reflectance measurements from monocultures of Bermuda grass and then applied to a test data set to predict N, NDF, and ADF. Statistical analyses showed that forage composition estimates from the radiometer were equivalent to those from the NIRS. Such a remote-sensing approach would enable real-time assessment of forage quality, would allow mapping of the nutritional landscape, could be used as a tool to better manage pastures and supplements, and would assist in making harvesting decisions.

Relationships among forage chemistry, rumination and retention time with intake and digestibility of hay by goats☆☆☆

Eight species of forage, a cool-season perennial (tall fescue ( Festuca arundinacea)) and annual grass (winter wheat (Triticum aestivum)), four warm-season perennial grasses (caucasian (Bothriochloa caucasica), plains (B. ischaemum), old world bluestem, bermudagrass (Cynodon dactylon), and eastern gamagrass (Tripsacum dactyloides)), a warm season annual (crabgrass (Digitaria sanguinalis)) and a perennial legume (alfalfa (Medicago sativa)), were each cut at two or three maturities to provide a wide array of quality difference (n = 20). Twenty wether goats (Capra hicus) were fed the hays in four different trials using an incomplete block design so that four different goats received each hay. Alfalfa produced the highest (25 g kg −1 body weight (BW)) and wheat the lowest (13.6 g kg −1 BW) organic matter (OM) intake. A number of the grasses provided less than 20 g kg −1 BW OM intake. Digestion of OM was also highest for alfalfa (>715 g kg −1 ) and lowest for bermudagrass (508 g kg −1 ). All measures and expressions of intake and digestibility were better related to ruminating and retention time than to forage chemistry, with the exception of crude protein digestibility. The best equations for predicting intake included a combination of mean retention time and forage acid detergent fiber (ADF) content (reciprocal and quadratic); that for digestibility included permanganate lignin (reciprocal), and the quadratic for ruminating and retention time. Equations for predicting the constraint on intake and digestible organic matter intake produced higher r 2 than those for either intake or digestibility. Digestibility of ADF and neutral detergent fiber (NDF) were poorly predicted with either chemistry ( r 2 ≤ 0.20), or ruminating time (r 2 = 0.43), but combinations of permanganate lignin content of NDF, retention and ruminating time produced reasonable equations. Published by Elsevier Science B.V.

Factors influencing tenderness in steaks from Brahman cattle

The objective of this study was to identify a set of explanatory variables for Warner-Bratzler shear force and myofibril fragmentation indices after 7, 14, and 21d of aging; and sensory tenderness after 14d of aging of steaks from Brahman cattle. Insoluble collagen was negatively associated (P<0.001) with all tenderness traits across aging periods, and regression coefficients ranged from 5.69±0.49 to 9.12±0.29N for Warner-Bratzler shear force. The effect of lean color score (P<0.05) in analyses of unadjusted traits was diminished when data were adjusted for contemporary group (calves of the same sex, fed in one pen, and slaughtered the same day). Insoluble collagen may be of special importance and offer a unique opportunity to improve palatability of steaks from purebred Brahman cattle.

Intramuscular fat and fatty acid composition of longissimus muscle from divergent pure breeds of cattle

The objective of this study was to compare the fatty acid (FA) composition of intramuscular fat from the LM of 3 divergent breeds of cattle: Angus (AN, n = 9), Brahman (BR, n = 7), and Romosinuano (RM, n = 11). Cattle were blocked by breed and finished 129 d before slaughter in one year and 157 d in the next year. Longissimus muscle samples were collected from each carcass between the 10th and 13th ribs, trimmed of external fat, frozen in liquid nitrogen, homogenized, and used for fat extraction, using a modified Folch procedure. Extracted fat was analyzed for FA by using a GLC system with an HP-88 capillary column. Fatty acid composition was expressed using both a normalized percentage (%) and gravimetric calculation (mg/g of fresh muscle tissue) in relation to degree of saturation, which was determined using a saturation index (ratio of total SFA to total unsaturated FA). Crude fat determination revealed that LM from AN purebred cattle had the greatest amount of intramuscular fat (7.08%; P = 0.001). Although intramuscular fat of LM from RM contained a reduced percentage of total SFA (P = 0.002) compared with AN, it had the greatest percentage of total PUFA (P < 0.001 and P = 0.020). The percentages of total MUFA were similar among the 3 breeds (P = 0.675). The gravimetric calculation, a measure of actual FA concentration, showed significantly greater concentrations of SFA (26.67 mg/g), MUFA (26.50 mg/g), and PUFA (2.37 mg/g) in LM from AN cattle, as compared with LM from BR and RM cattle (P < 0.001). Interestingly, BR purebreds had the least PUFA concentration (1.49 mg/g; P <or= 0.001) in the LM, although their intramuscular fat content was similar to that of RM (P = 0.924). Regardless of breed, the MUFA proportion was always the greatest (47.58%; P <or= 0.005), whereas PUFA was the least contributor to FA composition (1.49 to 2.37 mg/g and 4.36 to 8.78%; P < 0.001). Beef LM fatty acid composition was characterized by palmitic and oleic acids being the most abundant FA (P < 0.001). These results suggested a genetic variation in FA synthesis and deposition among breeds that influenced both marbling and its composition.

Effect of breed composition on phenotypic residual feed intake and growth in Angus, Brahman, and Angus × Brahman crossbred cattle

The influence of additive and nonadditive genetic effects and temperament on 4 postweaning feed intake and growth traits was evaluated in a group of 581 bull, heifer, and steer calves born in 3 Florida herds in 2006 and 2007. Calves had breed compositions ranging from 100% Angus (A) to 100% Brahman (B). They were randomly allocated to 24 pens each year by herd (Brooksville, Gainesville, Marianna, FL), sire group (A, 3/4 A 1/4 B, Brangus, 1/2 A 1/2 B, 1/4 A 3/4 B, and B), and sex (bull, heifer, and steer) in a GrowSafe automated feeding facility at Marianna. Calves were fed a concentrate diet during the 21-d adjustment and the 70-d trial periods. Individual feed intakes were recorded daily, and BW, chute scores, and exit velocities were recorded every 2 wk. Traits were phenotypic daily residual feed intake (RFI), mean daily feed intake (DFI), mean daily feed conversion ratio (FCR), and postweaning BW gain. Phenotypic RFI was computed as the difference between actual and expected feed intakes. Calves were assigned to 3 RFI groups: high (RFI greater than 0.9 kg of DM/d), low (RFI less than -0.9 kg of DM/d), and medium (RFI between mean +/- 0.9 kg of DM/d; SD = 1.8 kg of DM/d). The mixed model included the fixed effects of contemporary group (herd-year-pen), RFI group (except when trait was RFI), age of dam, sex of calf, age of calf, B fraction of calf, heterozygosity of calf, mean chute score, and mean exit velocity. Brahman fraction and heterozygosity of calf were nested within sex of calf for RFI and within RFI group for DFI, FCR, and postweaning BW gain. Random effects were sire and residual. Feed efficiency tended to improve (decreased RFI) as the B fraction increased. However, calves required larger amounts of feed per kilogram of BW gain (larger FCR) as the B fraction increased. Postweaning BW gain tended to decrease as the B fraction increased. Temperament traits were unimportant for all traits except exit velocity for DFI, suggesting perhaps a lack of variation for temperament traits in this herd, or that calves became accustomed to the level of handling pre- and postweaning, thus decreasing behavioral differences among them.

The use of near-infrared reflectance spectroscopy to define nutrient digestion of hay by cattle

Abstract Near-infrared reflectance spectroscopy (NIRS) has the potential to help redefine nutrient requirements and feeding standards. The spectral information obtained from a feed sample is much greater and more specific than the currently used conventional chemical procedures. Difference spectra between hays and feces from steers fed the hay were used to determine spectral areas of uniform digestion or indigestion. Digestion coefficients were calculated for each data point and the digestible absorption regressed on absorption for the hay. Above average apparent digestion occurred between 1450 and 1620 nm and between 2100 and 2200 nm. Below average apparent digestion occurred with sharp peaks at 1714, 2256, 2306, 2346 and 2382 nm. These represent aliphatic CH stretch and bend first overtone and combination bands and are usually associated with lipids, but may result from either feeds, sloughed animal tissue, or microbial residue. High correlations of organic matter digestion and hay spectra were found at 1990 and 2192 nm. These probably represent protein fractions but are shifted slightly from the peak absorption of proteins at 2000 and 2180 nm. Results also suggest uniform digestible fractions near 1990 and 2190 nm. The 2086 nm region produced an R2 of near zero indicating non-uniform digestion, probably from conflicting digestibilities of starch and cellulose.

Chemical composition of old world bluestem grasses as affected by cultivar and maturity.

Old world bluestem (OWB) gmsses (Bothdoc~ rpp.) have been used for herbage in the southern Great Plains for over 60 years, but release of new, weii-adapted cuitivars has led to a dramatic increase in use of these grasses in Oklahoma and adjacent areas during the iast 15 years. Little inform&ion is avaiiable on the chemical composition of OWB grasses. The purpose of this study was to obtain information on the chemicai composition of OWB grasses as affected by cuitivu and maturation. Forage samples for chemical analyses were obtained from a 2-year field experiment conducted on a Kirkland siit loam soil (Udertic Paleustoli). Ten harvest dates (l-week interval between harvests) and 3 plant parts (whole plant, leaf, and stem) were imposed by split-split plot arrangement on estabiished stands of ‘Caucasian’, ‘Ganadr’, ‘Pi&s*, and ‘WW-Spar’ blue&em. Responses of variables were neutral detergent fiber (NDF), add detergent fiber (ADF), add detergent iignin (ADL), and crude protein (CP). Concentrations of NDF, ADF, and ADL increased ln whole piant and stem samples during the ltl-week sampifng periods of both years. Quadratic equations best described changes in ADF during both years and in NDF and ADL in 1983, whereas ifnear equations best fitted changes in NDF and ADL in 1982. Concentration of NDF in leaves changed very ilttie with maturation, but Its change in whole plant and stems paraiieied that described for ADF and ADL. Concentrations of CP decreased in ail piant parts through harvest date eight (D-week oid growth), with the changes best described by quadratic quations. Changes ln ail constftuents were less affected by advancing maturity in leaves than in stems. Maturity had a much greater effect on concentration of all the chemical constituents than did cuittvu. Initial concentrations of NDF In all plant parts exceeded the kvei (ca 600 g kg*) at which intake would Ekely be affected. Concentrations of CP also deciined to levels by the 5th to 6th harvest dates, particulariy in whole piant and stem parts, insufficient to supply daily rquirements for most ciassss of mature beef cattle. The resuits point to the need to maintain and utflixe these grasses to the extent posdbie in a juvenile, actively growing state to provide nutrition for growing iivestock.

Evaluation of tropically adapted straightbred and crossbred beef cattle: Heifer age and size at first conception and characteristics of their first calves

The objectives of this work were to estimate genetic effects for age and size at estimated time of first conception, and temperament in straightbred and crossbred heifers (n = 554) produced from Romosinuano, Brahman, and Angus cattle, and to evaluate first-parturition performance of heifers, including calf birth weight, occurrence of calving difficulty, occurrence of poor vigor in their newborn calves, and calf mortality. At approximately 7 mo of age, weaned heifers were pastured with Mashona or Tuli bulls until confirmed pregnant. Body weight, hip height, exit velocity (m/s), and chute temperament score (1 = calm, no movement; 5 = continuous movement, struggling) were recorded at 28-d intervals until heifers averaged 19 mo of age. Age at first conception was estimated as age at calving minus 285 d. Regression analyses were used to estimate BW and hip height at age of first conception. Brahman heifers were older, heavier, and had greater hip height than other straightbred groups (P < 0.05) and most crossbred groups. Brahman and reciprocal Brahman-Angus heifers had greater (P < 0.05) exit velocity than Romosinuano and Angus heifers. Brahman sire and dam breed chute temperament scores were greater (P < 0.05) than those of all other breed groups. Estimates of heterosis for age at first conception were -53.7 ± 9.5 (-11%), -56 ± 10.1 (-11%), and -92.9 ± 11 d (-18%) for Romosinuano-Brahman, Romosinuano-Angus, and Brahman-Angus, respectively (P < 0.01). Heterosis was detected (P < 0.04) for Romosinuano-Brahman for BW (12 ± 4.3 kg, 3.7%) and hip height (1.3 ± 0.6 cm, 1%) at first conception. Maternal heterosis for calf birth weight was 3.6 ± 0.5 (12%) and 2.4 ± 0.6 kg (8.6%) for Romosinuano-Angus and Brahman-Angus. In Romosinuano-Brahman and Brahman-Angus, heterosis for exit velocity was 0.23 ± 0.09 (10%) and 0.5 ± 0.1 m/s (21%). The direct breed effect of Romosinuano was to reduce age (-58.2 ± 18.9 d), BW (-57.6 ± 10.5 kg), and hip height (-2.6 ± 1.1 cm) at the time of first conception (P < 0.01), and the direct Brahman effects (P < 0.001) were large and numerically positive for these traits (169.8 ± 20.8 d, 93.3 ± 11.6 kg, and 14 ± 1.2 cm). Use of Romosinuano in crossbreeding programs with Brahman may be useful for decreasing the age at first conception. The larger birth weights of calves born to Romosinuano-Angus cross heifers would not be desirable in southern cow-calf operations.