Chopping of whole-crop barley silage improves intake and live-weight gain of young dairy steers

This experiment evaluated the effect of chopping whole-crop barley silage on intake, diet selection and live-weight gain in young dairy steers. Whole-crop barley harvested at the dough stage of maturity and preserved as round bale silage was fed ad libitum in its long form or precision-chopped to 63 pen-housed dairy steers (average weight 173, s.d. 39 kg). In addition, each animal received 0.6 kg of soybean meal, 0.4 kg of barley grain and 0.08 kg of mineral feed daily. Chopping increased dry matter intake of whole-crop barley silage by 23% and live-weight gain by 22%. Higher concentrations of starch in the orts from steers when fed unchopped silage reflected sorting against grain, probably caused by long awns in the unchopped silage, which were not present in the chopped silage. No sorting against grain occurred in the chopped silage. Chopping increased intake of whole-crop barley silage and live-weight gain of young dairy steers, probably due to negative effects of long awns in the unchopped whole-crop barley silage on intake.     

Intake and digestion of whole-crop barley and wheat silages by dairy heifers

The effect of maturity at harvest on the digestibility and intake of large bale silage made from whole-crop barley and wheat when fed to growing heifers was evaluated. Two crops of spring barley (Hordeum distichum cv. Filippa and Kinnan) and 1 of winter wheat (Triticum aestivum cv. Olevin) were harvested at the heading, milk, and dough stages of maturity. The silage was fed to 36 dairy heifers in a balanced crossover experiment with 3 periods and 9 treatments (diets based on 3 crops and 3 stages of maturity), organized into 6 pairs of 3 × 3 Latin squares. No clear relationship was observed between intake and stage of maturity of whole-crop cereal silage, but intake was positively correlated to silage DM content (P < 0.001, r = 0.46) and negatively correlated to NDF content (P < 0.001, r = -0.42). Organic matter digestibility decreased between the heading and milk stages of maturity in all crops (P < 0.001), did not differ between the milk and the dough stages in the 2 barley crops, but increased in the wheat silage (P = 0.034). The NDF digestibility decreased between the heading and milk stages in all crops (P < 0.001), whereas it decreased in 1 barley crop (P < 0.001), increased in the other barley (P = 0.025), and was unchanged in the wheat between the milk and dough stages of maturity. Starch digestibility was less in the 2 barley crops compared with the wheat at the dough stage of maturity (P < 0.001). The feeding value of the whole-crop barley and wheat declined between the heading and milk stages of maturity, but thereafter the effect of maturity on the feeding value was minor.     

Effects of hydrochloric,valeric, and other volatile fatty acids on pathogenesis of ulcers in the nonglandular portion of the stomach of horses

OBJECTIVE: To identify in vitro effects of hydrochloric acid, valeric acid, and other volatile fatty acids (VFAs) on the pathogenesis of ulcers in the nonglandular portion of the equine stomach. SAMPLE POPULATION: Gastric tissues from 13 adult horses. PROCEDURE: Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance and conductance calculated after tissues were bathed in normal Ringer's solution (NRS) or NRS and hydrochloric, valeric, acetic, propionic, and butyric acids. Treated tissues were examined histologically. RESULTS: Incubation in 60mM valeric acid at pH < or = 7.0 abruptly and irreversibly abolished Isc, which was followed by a slower decrease in resistance and an increase in conductance. Incubation in 60mM acetic, propionic, and butyric acids and, to a lesser extent, hydrochloric acid at pH < or = 7.0 significantly decreased Isc, which was followed by an increase in resistance and a decrease in conductance. CONCLUSIONS AND CLINICAL RELEVANCE: Incubation in valeric acid at pH < or = 7.0 caused a dramatic decrease in mucosal barrier function in the nonglandular portion of the stomach. Changes in barrier function attributable to exposure to valeric acid were associated with histopathologic evidence of cellular swelling in all layers of the nonglandular mucosa. Because of its high lipid solubility, valeric acid penetrates the nonglandular gastric mucosa, resulting in inhibition of sodium transport and cellular swelling. Valeric acid and other VFAs in gastric contents may contribute to the pathogenesis of ulcers in the nonglandular portion of the stomach of horses.     

Evaluation of an Immunochromatographic Test to the Diagnosis of Canine Brucellosis Caused by Brucella canis

This study evaluated the performance of an immunochromatographic test (ICT) for the diagnosis of canine brucellosis caused by Brucella canis, comparing its results with that of the rapid slide agglutination test with and without the use of 2‐mercaptoethanol and the agar gel immunodiffusion test (AGID). The microbiological culture, PCR and clinical examination were used as reference. According to the results obtained in clinical examination, blood culture, culture of semen and vaginal swab and PCR in blood, semen and vaginal swab, a total of 102 dogs were divided into three groups: B. canis‐infected dogs (Group 1), B. canis‐non‐infected dogs (Group 2) and dogs with suspected brucellosis (Group 3). The diagnostic sensitivity of RSAT, 2ME‐RSAT, AGID and ICT in Group 1 was, respectively, 75%, 37.5%, 27.8% and 89.58%. The diagnostic specificity of RSAT, 2ME‐RSAT, AGID and ICT in Group 2 was, respectively, 91%, 100%, 100%, and 100%. In dogs with suspected brucellosis, 9.67% were RSAT positive, none was positive by 2ME‐RSAT, 3.22% were AGID positive and 6.45% were ICT positive. The main drawback concerning canine brucellosis diagnosis is the lack of a highly sensitive serological assay to be used as a screening test to the rapid identification of infected animals. The ICT showed a high diagnostic specificity and a diagnostic sensitivity value greater than that observed in the RSAT, 2ME‐RSAT and AGID. However, 10.41% of infected dogs had negative results by ICT. These dogs were positive by microbiological culture and/or PCR, indicating active infection and consequently a higher potential of spreading Brucella. Although rapid and simple to perform, the ICT lacked sensitivity to be used as a screening test.     

Feeding dairy calves and replacement heifers in South-western Sweden: a survey

Daily feed rations, their nutrient contents and live weight gains were recorded for calves and replacement heifers from birth to calving in 122 Swedish dairy herds. Preweaned calves were fed whole milk (45% of the herds), milk replacer alone or milk replacer combined with whole milk. Calf starters were the most frequently used concentrates for preweaned calves, whereas grain dominated for weaned calves and heifers. Grain was supplemented with protein concentrates until 6 months of age and at calving. Grass/clover hay was the dominant forage for preweaned calves, whereas grass/clover silage alone or in combination with hay was the most common forage for calves and replacement heifers from 6 months of age. Heifers grazed semi-natural grasslands, leys or a combination of semi-natural grasslands and leys in 33, 15 and 52% of the herds, respectively. According to Swedish recommendations, calves in a majority of the herds were fed too low concentrations of crude protein from weaning to 6 months of age and calves were fed too low a metabolizable energy content inadequate for a daily weight gain of 700 g at weaning. Median live weight gain from birth to calving was only 567 g per day. Correct feed ration formulations and strategic grazing management could be means to increase weight gain and hence to decrease rearing costs of calves and replacement heifers in Swedish dairy herds.     

Patterns of Follicular Growth in Superovulated Sheep and Influence on Endocrine and Ovarian Response

Objectives of this study were to characterize patterns of follicular development in sheep superovulated with purified follicle stimulating hormone (FSH) (OVAGEN^TM, ICP, Auckland, New Zealand) and to determine its influence on preovulatory events (onset of the oestrus behaviour and timing of the preovulatory luteinizing hormone surge) and ovarian response (ovulation rate and embryo yield). Number and size of all ≥ 23 mm follicles from the first FSH injection to withdrawal of progestagen sponges was determined by transrectal ultrasonography just prior to every FSH injection in nine Manchega ewes superovulated with eight decreasing doses (ml) (1.5 × 3, 1.25 × 2 and 1 × 3) of OVAGEN injected twice daily from 60 h before to 24 h after the withdrawal of 40 mg fluorogestone acetate sponges. Oestrous detection and jugular blood sampling for LH radioimmunoassay were performed every 3 h from 14 to 53 h after sponge removal and ovulation rate and number of embryos were determined 4 days after progestagen withdrawal. Administration of OVAGEN induced a significant rise (p < 0.0005) in the number of follicles ≥ 4 mm in size because of an increased growth in size of follicles from the first FSH injection to sponge removal, an increase in the number of newly detected follicles from 12 to 36 h of the first FSH dose (p < 0.005) and a decrease in regression rate from 24 h (p < 0.001). The number of follicles 2–3 mm in size at first FSH dose (10.4 ± 1.5) was positively correlated with the number of ≥ 4 mm follicles at 0 h (19.0 ± 2.7, p < 0.01). A higher number of ≥ 4 mm follicles at 0 h was related with an earlier appearance of oestrus (31.5 ± 1.5 h, p = 0.08) and LH surge (45.0 ± 2.3 h, p < 0.005), and a higher ovulation rate (18.2 ± 3.8, p < 0.005). On the other hand, the rate of embryo recovery was decreased in ewes with earlier preovulatory LH peaks (p < 0.005), with a shorter interval between oestrus and LH peak (p < 0.05).