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Fifty-two Angus x Gelbvieh rotationally crossed virgin, ovariectomized, or single-calf heifers were slaughtered after 100 d on a high-concentrate diet. Heifers from each treatment were approximately 31, 33, or 35 mo of age, and they produced 31 A, 5 B, and 16 C maturity carcasses. Because of the small number, B maturity carcasses were not included in this study. Number of A maturity carcasses decreased as age increased. No differences (P > .05) in slaughter weight, total weight gain, dressing percentage, longissimus muscle area, or kidney fat percentage existed between carcass maturity groups, but C maturity heifers had 3.56 mm more fat (P < .01) over the longissimus muscle than A maturity heifers. Marbling scores of [slight.sup.79] and [small.sup.0] for A and C maturity carcasses, respectively, did not differ (P > .05). The A and C maturity heifers had similar amounts of collagen and hydroxylysyl-pyridinium crosslinks in metacarpal bone cortex and in longissimus muscle. Neither means for panel tenderness nor Warner-Bratzler shear values differed (P > .05) between maturity groups. Coefficients of variation for tenderness were slightly higher in steaks from C maturity carcasses, but CV for shear values between A and C maturity groups were similar. Because inconsistent meat tenderness is a recognized problem in the beef industry, more research on tenderness variability within maturity and marbling groups is needed. This information, in addition to pooled SEM and differences between means, should aid in finding ways to reduce beef tenderness variability. Key Words: Bovines, Maturity, Collagen, Tenderness, Age

Fifty-three Angus/Gelbvieh rotationally crossed heifers were slaughtered after 100 d on a high-concentrate diet. The average slaughter age for each of three different groups was 31, 33, or 35 mo, which falls within the USDA's 30- to 42-mo age range for animals producing 'B' maturity carcasses. Each age group consisted of five or six heifers that had never been bred (virgin), six heifers ovariectomized at 1 yr of age (spayed), and six heifers that had weaned calves approximately 120 d postpartum (single-calf). Slaughter weight was higher (P < .05) for the virgin heifers but total weight gain in the feedlot was similar among the three groups. Single-calf heifers fed 100 d after weaning calves tended to be fatter than virgin or spayed heifers. Carcass maturity scores for the single-calf, virgin, and spayed heifers were different (P < .05); single-calf heifers produced carcasses that appeared older and spayed heifers produced carcasses that appeared younger. Maturity scores coupled with lighter and shorter metacarpal bone weights indicated single-calf heifers matured earlier (P < .05) than the other groups. Panel tenderness and Warner-Bratzler (WB) shear values of rib roasts from virgin, spayed, and single-calf heifers were determined. No differences among groups of heifers existed but scores within each group varied greatly. Marbling score was correlated (P < .05) with panel tenderness and shear force and the hydroxylysylpyridinium (HP) crosslink of muscle collagen was correlated (P Key Words: Heifers, Calving, Ovariectomized Females, Carcasses, Tenderness, Collagen

Eight cross-bred beef steers (initial BW = 241 ± 4.10 kg) were used in a 77-d feeding experiment to determine if ME intake can be determined from carbon emissions, oxygen consumption, and energy retention estimates. Steers were housed in a pen equipped with individual feed bunks and animal access was controlled by Calan gates and trained for 2 wk before starting the experiment. After training, steers were then randomly assigned to 1 of 3 treatments as a multiple of ME intake (MEx) at maintenance (7.43 Mcal of ME/d): 1.1 (1.1M, n = 3), 1.4 (1.4M, n = 2), and 1.8 (1.8M, n = 3). Diets fed were long-stemmed wheat hay (Triticum aestivum L.; 15% CP, 64% TDN) plus a daily supplement with 1.025 kg of alfalfa(Medicago sativa L.)/ wheat middling pellets (15% CP) delivered via an automated head-chamber system (GreenFeed, C-Lock, Inc., Rapid City, SD) to measure CO2 and CH4 emission, and O2 consumption. On d 1, 14, 35, 56 and 77 of the experiment, BW was recorded after a 17-h fast and used to calculate retained energy (RE) and adjust feeding rates of the diets. Retained energy by the steers was calculated using the NASEM (2016) procedures. Heat production (HP) was calculated from gas emission and consumption estimates and urinary N output [Nurine = 5.91 x dietary CP (%) - 21.52, g/d] using the Brouwer (1965) equation. Intake of ME was calculated by adding HP and RE. Total DMI linearly increased (P < 0.01) with MEx (4.10, 5.44, and 7.41 kg/d for 1.1M, 1.4M, and 1.8M, respectively) and steer ADG (0.12, 0.29, and 0.65 kg, respectively) increased linearly (P < 0.01) with increasing MEx. Carbon dioxide emissions (3,846, 4,106, and 4,468 g/d, respectively) and O2 consumption (3,406, 3,514, and 3,964 g/d, respectively) increased linearly (P ≤ 0.01) with increasing MEx, but CH4 did not differ (P > 0.41; 162, 170, and 170 g/d, respectively). Energy retention (0.32, 0.72, and 1.89 Mcal/d, respectively) and HP (11.35, 11.80, and 13.24 Mcal/d, respectively) by steers increased (P < 0.01) linearly with MEx. Hence, the predicted ME intake increased linearly (P < 0.01) from 1.1M to 1.8M (11.67, 12.52, and 15.13 Mcal/d, respectively). These results indicate that measurements of CO2 and CH4 emissions, and O2 consumption with an automated head-chamber system can be used to provide reasonable estimates of ME intake and HP for grazing ruminants. [ABSTRACT FROM AUTHOR]

Acetylcholinesterase (AChE) cDNA from individual field-collected diazinon-resistant horn flies was amplified by RT-PCR. Sequencing of the amplification products revealed that 8/12 of the diazinon-resistant horn flies contained a point mutation previously associated with resistance to organophosphates in house flies and Drosophila, strongly suggesting that this cDNA encodes the AChE that is the target site for organophosphate (OP) pesticide. The point mutation (G262A) resulted in a shift from glycine to alanine in the mature HiAChE amino acid sequence at position 262. Allele-specific PCR and RLFP assays were developed to diagnose the presence or absence of the G262A mutation in individual flies. Use of the allele-specific assays each demonstrated the presence of the G262A mutation in 10 of 12 individual field-collected flies, demonstrating higher sensitivity than direct sequencing of RT-PCR amplification products. The G262A mutation was found in additional fly populations previously characterized as OP-resistant, further supporting that this AChE is the target site for OP pesticide. The allele-specific assay is a useful tool for quantitative assay of the resistance allele in horn fly populations.

Body condition scores (BCS) of ovariectomized estradiol-treated ewes were controlled to examine effects of suboptimum BCS on insulin-like growth factor (IGF)-I, IGF-binding proteins (IGFBPs), and LH in the anterior pituitary gland, hypophyseal stalk-median eminence (SME), and circulation. Serum LH increased in ewes with BCS (1 = emaciated, 9 = obese) > 3 (HIGH-BCS), but not in ewes with BCS

Twenty-six trichothecene mycotoxins produced by Fusarium sporotrichioides (MC-72083) and Fusarium sambucinum were screened for relative cytotoxicity in cultured baby hamster kidney (BHK-21) cells. The relative cytotoxicity was measured as LC100. The most cytotoxic trichothecenes were T-2 toxin (5 ng/ml) and the recently isolated 4-propanoyl HT-2 (5 ng/ml) and 3'-hydroxy T-2 toxin (5 ng/ml). T-2 tetraol (1 x 10(4) ng/ml), 8-beta-hydroxytrichothecene (1 x 10(4) ng/ml), sporotrichiol (2 x 10(4) ng/ml), 8-oxodiacetoxyscirpenol (6 x 10(4) ng/ml) and 8-acetyl T-2 tetraol (1 x 10(5) ng/ml) were the least toxic of the regular trichothecenes. None of the modified trichothecenes or the apotrichothecene were very cytotoxic: 8-beta-hydroxysambucoin (2 x 10(3) ng/ml), FS-1 (5 x 10(3) ng/ml), 8-alpha-hydroxysambucoin (8 x 10(4) ng/ml) and trichotriol (1 x 10(5) ng/ml). The modified trichothecenes, FS-2 and FS-3, were not toxic even at 1 x 10(5) ng/ml. The baby hamster kidney cell bioassay proved to be a very sensitive and reproducible means of screening new trichothecene mycotoxins for relative cytotoxicity.

From the stem bark of Erythrina eriotriocha, a novel isoflavone, eriotriochin has been isolated and characterized, in addition to known compounds auriculatin, dihydroauriculatin, and 3'-O-methylorobol. The structure of compound 1 was determined by COSY, selective INEPT, 2D HMBC, NOESY, DEPT, and other spectroscopic techniques.

In addition to the known compounds erythinasinate [1] and abyssinone V [2], two new flavonoids were isolated from the CHCl3 extract of the stem bark of Erythrina eriotriocha and characterized by spectroscopic techniques as 3'-prenylnaringenin [3] and 2'-hydroxy-5'-methoxybiochanin A [4].

A rapid and sensitive method for the determination of 1-aminocyclopropane-1-carboxylic acid (ACC) in apple tissues is described. This method is based on the derivatization of ACC with phenylisothiocyanate, and the subsequent separation and quantification of the resulting phenylthiocarbamyl-ACC by reverse-phase high-pressure liquid chromatography. Phenylthiocarbamylation of ACC (and other amino acids) in apple extracts is complete within 20 min at room temperature. After removing solvents and reagent, the phenylthiocarbamyl derivatives are separated on an octadecyl reverse-phase column, eluted with a mixture of acetonitrile and sodium acetate buffer at pH 4.6, and monitored with a uv detector set at 254 nm. An analysis of apple extract can thus be achieved in 23 min and detect quantities as low as 1 pmol. Assays have been done to compare the efficiency of this method with that of a method using an ion-exchange amino acid analyzer and with that of Lizada and Yang's method [(1979), Anal. Biochem. 100, 140-145]. The latter method proved to yield markedly less accurate results than the other two, but the derivatization-HPLC method was preferred because of simplicity of operation and a better separation of ACC.

Garcinia epuctata is an indigenous medicinal plant of Cameroon from which taxifolin 6-C-glucoside was isolated and characterized. The nmr assignments obtained from COSY and INAPT experiments are reported for the first time.