Forage quality of white clover (Trifolium repens L.) × Caucasian clover (T. ambiguum M. Bieb.) hybrids and their grass companion when grown over three harvest years

Interspecific hybrids between white clover (Trifolium repens L.) and Caucasian clover (Trifolium ambiguum M. Bieb.) have been developed to introgress the rhizomatous growth habit into white clover, to increase persistence and drought tolerance. The forage quality of T. repens, T. ambiguum and the backcross 1 (BC1) and backcross 2 (BC2) hybrids and companion grass, when grown in mixtures with an intermediate perennial ryegrass (Lolium perenne L.) under a cutting‐only management, was measured. In vitro dry‐matter digestibility (DMD), water‐soluble carbohydrate (WSC) and crude protein (CP) concentrations of the legume and grass fractions were measured throughout the growing season over three harvest years. Trifolium repens had a lower WSC but a higher CP concentration than the perennial ryegrass companion in all harvest years and at all cuts. The legume fractions from the BC1 and BC2 hybrid plots had a higher WSC and a lower CP concentration but an in vitro DMD value comparable with white clover throughout the growing season and in each harvest year. The grass fractions from the mixtures with the backcross hybrids had a higher WSC and a lower CP concentration than the grass fraction from the T. repens plots, in all harvest years and throughout the growing season. No difference in in vitro DMD between parental species and backcross hybrids was observed. The implications of these results for the development of these hybrids and animal performance are discussed.     

Polka dot grouper Cromileptes altivelis fingerlings require high protein and moderate lipid diets for optimal growth and nutrient retention

An 8‐week comparative slaughter experiment was carried out to determine the effect of dietary protein and lipid on growth, apparent digestibility (AD) and nutrient retention of polka dot grouper Cromileptes altivelis. Fingerlings were fed diets that varied in crude protein (CP) at 55 g kg^?1 increments between 410 and 630 g kg^?1 dry matter (DM) and at either a moderate (150 g kg^?1 DM) or high (240 g kg^?1DM) lipid concentration. Each diet was fed to satiety twice daily to four replicate tanks (110 L) of fish. One replicate block of tanks comprised 150 fish of mean (±SD) initial weight of 9.6 ± 0.29 g, which were distributed equally to 10 tanks. The other three replicate blocks of tanks comprised 300 fish of 12.6 ± 0.45 g, which were distributed equally to 30 tanks. Tanks were provided with filtered and heated (29 ± 0.5 °C) seawater in a flow‐through system within a laboratory where photoperiod was maintained at 12 : 12 h light–dark cycle. Voluntary food intake was not significantly affected by either the CP or lipid concentration of the diet (mean ± SD of 1.93 ± 0.146 g week^?1) but there was a trend for intake to be higher on the moderate compared with the high lipid diets (mean ± SEM of 1.97 versus 1.89 ± 0.033 gweek^?1, respectively). Daily growth coefficient (DGC) and food conversion ratio (FCR) improved linearly (P < 0.01) with increasing dietary CP (from 0.94 to 1.35% day^?1 for DGC and 1.58 to 1.00 g DM g^?1 wet gain for FCR) and these responses were almost coincident for each of the lipid series. The AD of CP increased linearly with increasing dietary CP (from 46.8 to 74.1%) and was independent of dietary lipid. Apparent digestibility of energy increased curvilinearly with increasing dietary CP, with the quadratic component being more prominent for the high‐lipid series. Increasing the amount of lipid in the diet markedly increased the lipid content of the fish from an initial composition (mean ± SD) of 173 ± 7.3 g kg^?1 to a final composition (mean ± SEM) of either 217 or 250 ± 5.9 g kg^?1 for moderate and high‐lipid series, respectively. Total body lipid content tended to increase linearly with increasing dietary CP for the high‐lipid series but with an opposite effect for the moderate‐lipid series. The retention of digestible nitrogen decreased linearly with increasing dietary CP but at a steeper rate for the moderate, compared with the high, lipid series (from 62.7 to 35.7%, slope ?0.115 for moderate‐lipid and 54.6 to 41.9%, slope ?0.050 for high‐lipid). A quadratic function of dietary CP concentration best explained the retention of digestible energy with the curvilinearity being more marked for the high, compared with the moderate, lipid diet series. While there was some indication that ingested lipid spared dietary protein, the results showed a far greater propensity of polka dot grouper fingerlings to use protein as the prime dietary energy source. Diets for juvenile polka dot grouper should contain not less than 440 g digestible protein kg^?1 DM and at least 150 g lipid kg^?1 DM.     

Nitrous oxide emissions and methane oxidation by soil following cultivation of two different leguminous pastures

 Nitrous oxide (N₂O) emissions and methane (CH₄) consumption were quantified following cultivation of two contrasting 4-year-old pastures. A clover sward was ploughed (to 150–200 mm depth) while a mixed herb ley sward was either ploughed (to 150–200 mm depth) or rotovated (to 50 mm depth). Cumulative N₂O emissions were significantly greater following ploughing of the clover sward, with 4.01 kg N₂O-N ha^–1 being emitted in a 48-day period. Emissions following ploughing and rotovating of the ley sward were much less and were not statistically different from each other, with 0.26 and 0.17 kg N₂O-N ha^–1 being measured, respectively, over a 55-day period. The large difference in cumulative N₂O between the clover and ley sites is presumably due to the initially higher soil NO₃ ^– content, greater water filled pore space and lower soil pH at the clover site. Results from a denitrification enzyme assay conducted on soils from both sites showed a strong negative relationship (r=–0.82) between soil pH and the N₂O:(N₂O+N₂) ratio. It is suggested that further research is required to determine if control of soil pH may provide a relatively cheap mitigation option for N₂O emissions from these soils. There were no significant differences in CH₄ oxidation rates due to sward type or form of cultivation. Received: 1 November 1998     

Caecal intussusceptions and typhlocolitis in horses with severe Gastrodiscus aegyptiacus infestation

The intestinal trematode Gastrodiscus aegyptiacus (G. aegyptiacus) has been recognised in equids around the world for many years, but its pathogenicity is yet to be confirmed. This report describes seven cases of severe G. aegyptiacus infestation, including six cases of caecal intussusception.     

Early assessment of processing strawberries for colour

Summary It is possible to select strawberry cultivars that give a satisfactory, naturally coloured canned product as an alternative to the commercially dyed one. Spectrophotometric measurements of the syrup from cans, the canned fruit and fresh fruit were compared with visual scoring. A preliminary screening for colour based on visual assessment of fresh flesh colour is possible.     

The effects of corn silage dry matter content and sodium bicarbonate addition on nutrient digestion and growth by lambs and calves

One lamb and three calf trials were conducted to determine if interactions existed between the effects of dry matter (DM) content of corn silage at harvest and sodium bicarbonate supplementation on diet digestibility, nitrogen balance, rate and site of digestion and feedlot performance. Corn plants were harvested from the same field when DM content was approximately 31% (early; E) or 44% (late; L). Sodium bicarbonate (1.2% of DM intake) was added in a completely mixed ration. When lambs were offered diets ad libitum, (trial 1), intakes were greater (P less than .05) for L-silage diets, but apparent digestibilities were similar. Nitrogen balance was greater for sodium bicarbonate-supplemented diets, and was a reflection of greater (P less than .10) DM intakes for these diets. At similar diet DM intakes, N balance was greater for L-silage diets, with no effects measured due to sodium bicarbonate addition. When growing, abomasally cannulated heifers (trial 2) were offered diets 12 times per day, a significant interaction among treatments was measured for total tract and acid detergent fiber (ADF) digestion. Adding bicarbonate to the E-silage diet increased (P less than .05) digestion by 9.1 percentage units (66.4 vs 75.5%) but decreased digestibility of the L-silage diet by 4.2 percentage units (73 vs 68.8%). Grams of ADF apparently digested in the rumen followed the same pattern as for total tract digestion. In trial 3, ruminal rates of liquid and particulate passage and in situ rats of NDF digestion were determined using four rumen-cannulated heifers calves.(ABSTRACT TRUNCATED AT 250 WORDS)     

Association of brook trout and Oncorhynchus spp. with large wood jams in a Lake Superior tributary in a northern old‐growth watershed

Wood in streams functions as fish habitat, but relationships between fish abundance (or size) and large wood in streams are not consistent. One possible reason for variable relationships between fish and wood in streams is that the association of fish with wood habitat may depend on ecological context such as large‐scale geomorphology. We studied the relationship between salmonid assemblages and large wood jams (LWJ) in four settings that differed geomorphically at the scale of the stream corridor along a tributary to Lake Superior in old‐growth conifer–hardwood forest in northern Michigan. The focal fish species of this study were brook trout (Salvelinus fontinalis), which were wild in the stream. Relocation efforts for coaster brook trout (an adfluvial life history variant of brook trout) were ongoing in the study stream. We measured fish abundance and length in pairs of pools of similar size and substrate, but varying in the presence of LWJ; this allowed us to evaluate associations of fish simply with the presence of LWJ rather than with other channel or flow‐shaping functions of LWJ. The length of Oncorhynchus spp. and young introduced brook trout was not strongly correlated with LWJ presence; however, the presence of LWJ in pools was positively correlated with larger wild brook trout. We also found that the correspondence of LWJ with the abundance of salmonids appears to be moderated by the presence of alternative habitat in this relatively natural, old‐growth forest stream.     

The role of antibody in protection against African swine fever virus

Intraperitoneal immunization of pigs with anti-African swine fever virus (ASFV) antibody protected them against the effects of challenge with ASFV. This protection, which was exemplified by a reduction in pyrexia and viraemia plus an increased survival time, appeared to be mediated through the effects of complement-dependent antibody-mediated cytotoxicity (CDAC) or antibody dependent cell mediated cytotoxicity (ADCC). Experiments suggested that the reduction in viraemia was associated with complement lysis whereas protection was conferred by ADCC.     

Extraocular myositis in the dog.

Extraocular myositis is a rare condition in the dog and is poorly reported in the peer-reviewed veterinary literature. This case series and review are designed to be of value to those veterinary ophthalmologists seeking to investigate the disease further and also to veterinarians outside the specialty, for whom this may be their first introduction to the disease.