Feeding combinations of dry corn and wheat to finishing lambs and cattle

Two finishing trials, one with lambs and one with cattle, were conducted to determine the effect of combinations of dry corn (whole or rolled) with dry rolled wheat on animal performance. The cattle (mixed crossbred yearlings) trial also evaluated methods of getting cattle to full feed by stepping-up using either grain combinations or dry rolled corn and then feeding the appropriate grain combination. In the lamb trial, as the level of dry whole corn increased in the diet of 80 Rambouillet X Suffolk lambs (29 kg), feed intake (linear, P less than .01), gain (linear, P less than .01; quadratic, P less than .15) and feed efficiency (linear, P less than .01; quadratic, P less than .15) were improved. The major improvement occurred in the first 30 d of feeding when feed efficiency was improved (linear, P less than .01; quadratic, P less than .01) by the inclusion of dry whole corn. In the cattle trial (272 mixed crossbred yearling cattle, avg = 358 kg), as the level of dry rolled corn increased, feed intake (linear, P less than .01), gain (linear, P less than .01; quadratic, P less than .01) and feed efficiency (linear, P less than .05; quadratic, P less than .05) were improved. Cattle fed 67 or 33% dry rolled corn with 33 or 67% dry rolled wheat gained 4% faster and 4.4% more efficiently than the average performance of cattle fed 100% corn or wheat. Cattle stepped-up on dry rolled corn and then switched to 100% wheat, tended to gain faster (.1 kg/d) than cattle stepped-up on 100% wheat.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vitro exposure of bovine morulae to Ureaplasma diversum.

Ureaplasma diversum has been associated with infertility in the cow experimentally and in naturally occurring cases. However, the pathogenic mechanism is undetermined. The purpose of this study was to determine whether ureaplasmas are pathogenic for bovine morulae in vitro. Twenty-one morulae were recovered from three superovulated, mature, Holstein cows six or seven days postestrus. The embryos were divided into three groups (A,B,C) and incubated for 16 hours at 37 degrees C in humidified air with 10% CO2. Group A was incubated in embryo culture medium alone, Group B was incubated in culture medium with sterile ureaplasma broth added and Group C was incubated in culture medium containing 1.7 X 10(6) colony forming units Ureaplasma diversum strain 2312. After incubation, the morulae were examined using an electron microscope. Structures morphologically identical to U. diversum were present on the outer surface of the zonae pellucidae of all the morulae exposed to the organism and none were present on the unexposed control embryos. No other morphological differences were observed in either the ureaplasma-exposed embryos or the two groups of control embryos. Ureaplasma diversum was isolated from three of the five embryos incubated in culture medium with sterile ureaplasma broth added. These three embryos were recovered from one donor cow which cultured positive for U. diversum from the vulva and flush fluid. This finding suggests that the contaminating organisms entered the embryo culture wells either in the embryo collection medium or attached to the embryos.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protein A gold identification of ureaplasmas on the bovine zona pellucida.

The object of this study was to develop a prefixation protein A gold labelling technique for Ureaplasma diversum and to apply this to bovine embryos. Sixteen hour cultures of Ureaplasma diversum strain 2312 were incubated with either specific antiserum or nonimmune serum, followed by exposure to protein A gold and negative staining. The ureaplasmas which were incubated with specific antiserum were labelled with gold particles while those ureaplasmas which were incubated with nonimmune serum were not labelled. Twenty-three unhatched, day 7 bovine embryos were then incubated in either embryo culture medium (ECM) alone, ECM with sterile ureaplasma broth added or ECM with 1.7 X 10(6) colony forming units of Ureaplasma diversum strain 2312 per embryo. After 16 hours, the embryos were washed twice and incubated with either specific antiserum or nonimmune serum. The embryos were then incubated with medium containing protein A gold and examined by electron microscopy. No ureaplasmas were identified on the zona pellucida of the control embryos. Ureaplasmas were identified on the outer surface of the zona pellucida of 13 of the 17 embryos which had been exposed to the organism. Of these, the embryos which were incubated with specific antiserum had labelled ureaplasmas while the embryos which were incubated with nonimmune serum had unlabelled ureaplasmas on the zona pellucida. It was concluded that the protein A gold method was a suitable technique for the identification of ureaplasmas in EM preparations. The presence of ureaplasmas on the outer surface of the bovine zona pellucida following in vitro exposure to the organism was confirmed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induced non-enzymatic browning of soybean meal. I. Effects of factors controlling non-enzymatic browning on in vitro ammonia release

Non-enzymatic browning was tested as a means of suppressing degradation of soybean meal (SBM) by ruminal microbes in five trials with in vitro ammonia release as the response criterion. Treatments imposed on SBM included reducing sugar source (xylose, glucose, fructose and lactose), reducing sugar level (1, 3 and 5 mol/mol SBM-lysine), pH (6.5, 8.5 and 10.0), dry matter (DM) content (65, 70, 75, 80, 85 and 90%) and varying lengths of heating time (0 to 90 min) at 150 C. Samples heated under conditions that promoted non-enzymatic browning gave greater (P less than .01) ammonia release suppression that when SBM was heated without these treatments. Xylose was the most reactive sugar, but extended heating of SBM containing glucose, fructose or lactose resulted in ammonia release similar to xylose. Increasing sugar level from 1 to 5 mol/mol SBM-lysine caused linear decreases (P less than .01) in ammonia release for xylose, glucose and fructose, but not lactose. Ammonia release was higher (P less than .01) at pH 6.5 than pH 8.5 and 10.0, and higher (P less than .01) at pH 9.5 than pH 10.0. Rate of non-enzymatic browning decreased when samples containing greater than 80% DM were heated. These results are interpreted to show that controlled non-enzymatic browning may be effective for reducing ruminal degradation of SBM.     

Response to monensin in cattle during subacute acidosis

A steer metabolism study was conducted to measure changes in ruminal and blood components in response to monensin level following an abrupt switch from forage to a concentrate diet. Six ruminal-cannulated crossbred steers (373 kg) were fed either 0, 150 or 300 mg monensin per head daily in a replicated 3 X 3 Latin-square design. In all treatments, ruminal pH declined to a low of 5.4 to 5.6 12 h post-feeding, suggesting steers experienced subacute acidosis. Also in the first 12 h post-feeding, all treatments exhibited nearly a twofold increase in total ruminal volatile fatty acid (VFA) concentrations, while peak ruminal lactate concentrations ranged from .86 to 1.50 mM. During the entire 48-h period, there were no significant treatment differences in blood pH, HCO3- or ruminal lactate, although there was a trend of higher ruminal and blood lactate associated with increased level of monensin supplementation. Feeding higher levels of monensin resulted in higher pH and propionate with lower acetate and butyrate concentrations. Increasing the level of monensin fed resulted in reduced (P less than .01) total ruminal VFA concentrations. Ruminal pH was more highly correlated to total ruminal VFA concentrations (r = -.69, P less than .01) than lactate concentrations (r = -.14, P less than .10). Results from this study indicate the significance of total ruminal organic acid concentration rather than ruminal lactate concentration during subacute acidosis. Monensin maintained a higher ruminal pH by reducing concentrations of VFA.     

Comparative functional responses of native and high‐impacting invasive fishes: impact predictions for native prey populations

Comparative functional responses (FRs) can predict impacts of invasive species, including piscivorous fishes, via quantifying their depletion of native food resources as a function of prey density. The utility of FRs for predicting impacts on prey populations by invasive fishes of different trophic guilds was tested here by comparing the FRs of the invaders Cyprinus carpio and Carassius auratus, with three native, trophically analogous fishes, Barbus barbus, Squalius cephalus and Tinca tinca. Chironomid larvae and Gammarus pulex were used as prey items. Predictions, developed from studies on the foraging of C. carpio and C. auratus in the literature, were that the invaders would have significantly higher consumption rates for chironomids than the native fishes, but not for G. pulex. Mean consumption rates for chironomids were significantly lower for both invaders than B. barbus and S. cephalus, but were similar to T. tinca. Barbus barbus had a significantly lower consumption rate of G. pulex than both invaders, but there were no significant differences between S. cephalus, T. tinca and the invaders. All FRs were type II, with FR curves for the invaders preying upon chironomids never being significantly higher than the native fishes, contrary to predictions. For G. pulex, some significant differences were apparent between the invaders and native fishes, but again were contrary to predictions. These results indicated that when predation impacts of invasive fishes could also be a function of their population density and body sizes, these parameters should be incorporated into FR models to improve impact predictions.     

Coexisting invasive gobies reveal no evidence for temporal and trophic niche differentiation in the sublittoral habitat of Lake Erhai,China

Niche differentiation facilitates the coexistence of species within a community through avoidance of competition via mechanisms involving spatial, temporal and/or trophic dimensions. Where invasive species coexist in their non‐native range, niche differentiation could allow their persistence at higher levels of abundance. Here, we tested whether there was temporal and/or trophic niche differentiation between two congeneric invasive goby species (Rhinogobius cliffordpopei and Rhinogobius giurinus) in the sublittoral habitat of Lake Erhai (south‐west China) through quantifying their diel and seasonal rhythm of locomotion activities, feeding activities and diet composition. Both species displayed two similar diel peaks in activity and two main feeding periods (6:00–10:00 and 18:00–22:00), with rhythms of locomotion and feeding activity not differing significantly between the species in each season. Their diets had a high degree of overlap, being primarily composed of macrozooplankton, aquatic insects and shrimp larvae, with no diel changes across the seasons. Thus, in this habitat, there was no clear temporal or trophic niche differentiation between the invasive congeners, indicating their coexistence with high temporal and trophic overlap. In conjunction with data from the littoral and profundal habitats, the gobies revealed different strategies across the habitats (e.g. spatial segregation, trophic niche differentiation) that minimised their competitive interactions and promoted their coexistence. This suggests that the interactions of invasive fishes during the integration into native communities can be context dependent, varying according to factors including habitat and the availability of food resources.     

Quantifying trophic interactions and niche sizes of juvenile fishes in an invaded riverine cyprinid fish community

Quantifying feeding interactions between nonindigenous and indigenous fishes in invaded fish communities is important for determining how introduced species integrate into native food webs. Here, the trophic interactions of invasive 0+ European barbel Barbus barbus (L.) and the three other principal 0+ fishes in the community, Squalius cephalus (L.), Leuciscus leuciscus (L.) and Phoxinus phoxinus (L.), were investigated in the River Teme, a River Severn tributary in Western England. B. barbus has been present in the River Teme for approximately 40 years. Analyses of stomach contents from samples collected from three sites between June and September 2015 revealed that, overall, fishes displayed a generalist feeding strategy, with most prey having low frequency of selection. Relationships of diet composition versus body length and gape height were species‐specific, with increasing dietary specialisms apparent as the 0+ fishes increased in length and gape height. The trophic niche size of invasive B. barbus was always significantly smaller than S. cephalus and L. leuciscus and was significantly smaller than P. phoxinus at two sites. This was primarily due to differences in the functional morphology of the fishes; 0+ B. barbus were generally restricted to foraging on the benthos, whereas the other fishes were able to forage on prey present throughout the water column. Nevertheless, the invasive B. barbus were exploiting very similar prey items to populations in their native range, suggesting these invaders were strongly pre‐adapted to the River Teme and this arguably facilitated their establishment and invasion.