Nitrogen Metabolism in the Rumen

https://kenanaonline.com/files/0028/28692/Citrus%20by-products%20as%20ruminant%20feeds.pdf

Citrus by-products as ruminant feeds: A review

Nutritional Management of Transition Dairy Cows: Strategies to Optimize Metabolic Health

Effects of rumen-undegradable protein on dairy cow performance: a 12-year literature review.

Summary
Flowers produce a plethora of secondary metabolites but only nectar sugars, floral pigments and headspace volatiles have been examined in the context of pollinator behavior. We identify secondary metabolites in the headspace and nectar of glasshouse- and field-grown Nicotiana attenuata plants, infer within-flower origins by analyzing six flower parts, and compare the attractiveness of 16 constituents in standardized choice tests with two guilds of natural pollinators (Manducasexta moths and Archilochus alexandri and Selasphorus rufus hummingbirds) and one nectar thief (Solenopsis xyloni ants) to determine whether nectar metabolites can ‘filter’ flower visitors: only two could. Moths responded more strongly than did hummingbirds to headspace presentation of nicotine and benzylacetone, the most abundant repellent and attractant compounds, respectively. For both pollinators, nectar repellents decreased nectaring time and nectar volume removed, but increased visitation number, particularly for hummingbirds. Fewer ants visited if the nectar contained repellents. To determine whether nicotine reduced nectar removal rates in nature, we planted transformed, nicotine-silenced plants into native populations in Utah over 2 years. Plants completely lacking nicotine in their nectar had 68–70% more nectar removed per night by the native community of floral visitors than did wild-type plants. We hypothesize that nectar repellents optimize the number of flower visitors per volume of nectar produced, allowing plants to keep their nectar volumes small.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2006.02995.x

Making sense of nectar scents: the effects of nectar secondary metabolites on floral visitors of Nicotiana attenuata

Summary 1. Secondary compounds are common in floral nectar but their relative effects on nectar consumption and utilization in nectarivorous birds are unclear. 2. We studied the effect of two pyridine alkaloids, nicotine and anabasine, present in Tree Tobacco ( Nicotiana glauca ) nectar, on food consumption, gut transit time and sugar assimilation efficiency of the Palestine Sunbird ( Nectarinia osea ), a pollinator of N. glauca in east Mediterranean ecosystems. 3. Sunbirds demonstrated dose-dependent deterrence; they were not deterred by the lowest natural concentrations of these alkaloids in nectar (0·1 ppm nicotine and 0·6 ppm anabasine) but they were significantly deterred by the average concentrations detected in nectar (0·5 ppm nicotine and 5 ppm anabasine). 4. The two pyridine alkaloids reduced gut transit time (by 30‐42%) and sugar assimilation efficiency (by 9‐17%) compared with the control alkaloid-free diet. 5. Sunbirds are able to cope with low, but not average, concentrations of nicotine and anabasine in N. glauca nectar. If sunbirds are efficient pollinators of N. glauca they may induce selection on it to reduce pyridine alkaloid production in the nectar. Alternatively, high concentrations in some N. glauca plants may lead the birds to visit more plants with lower alkaloid concentrations. Hence, they will be more efficient pollinators, especially if other nectar-producing plants are scarce.

/pdf/limited-ability-of-palestine-sunbirds-nectarinia-osea-to-5ccfjy7y58.pdf

Limited ability of Palestine Sunbirds Nectarinia osea to cope with pyridine alkaloids in nectar of Tree Tobacco Nicotiana glauca

Effects of prepartum somatotropin and monensin on metabolism and production of periparturient Holstein dairy cows.

Partitioning of Amino Acids Flowing to the Abomasum into Feed, Bacterial, Protozoal, and Endogenous Fractions

Effect of the Degradation of Organic Matter and Crude Protein on Ruminal Fermentation in Dairy Cows

Sex-specific foraging behaviour might be influenced by digestive constraints. However, evidence for sex differences in digestive performance is limited. Various physiological traits are known to be body size dependent. Therefore, we hypothesized that body size differences between male and female birds may lead to differences in their digestive characteristics. We predicted that if food intake and digestive functions are only governed by body mass, then males that are heavier than females would have higher food intake, food assimilation efficiency and gut transit time, but not after controlling for the effect of body mass. We fed a diet of equicaloric solutions of sucrose and a 1:1 mixture of glucose and fructose (hexose mixture) solutions to Palestine sunbirds (Nectarinia osea). When fed sucrose solutions, males had longer transit times but similar absorption efficiencies as females. Transit times, corrected for differences in body mass and food intake, were still longer in males than in females when fed on sucrose solutions. The sex-specific differences in transit time disappeared when the birds were fed the hexose mixture. Our results suggest that males take longer to digest than females when fed on sucrose-rich nectars as opposed to hexose-rich nectars, and therefore can allow themselves a relatively lower digestive capacity. This may suggest sex-specific co-evolution of sunbirds within mixed plant communities, which have both sucrose- and hexose-rich nectar-producing plants. Furthermore, future studies on digestion in birds may pay attention to sex-specific differences.

/pdf/sex-differences-in-food-intake-and-digestive-constraints-in-3f55khhssc.pdf

A. Arieli

Papers

Limited ability of Palestine Sunbirds Nectarinia osea to cope with pyridine alkaloids in nectar of Tree Tobacco Nicotiana glauca

Effects of prepartum somatotropin and monensin on metabolism and production of periparturient Holstein dairy cows.

Partitioning of Amino Acids Flowing to the Abomasum into Feed, Bacterial, Protozoal, and Endogenous Fractions

Effect of the Degradation of Organic Matter and Crude Protein on Ruminal Fermentation in Dairy Cows

Sex differences in food intake and digestive constraints in a nectarivorous bird.