Relevance of dietary protein concentration and quality as risk factors for the formation of calcium oxalate stones in cats

The role of dietary protein for the development of feline calcium oxalate (CaOx) uroliths has not been conclusively clarified. The present study evaluated the effects of a varying dietary protein concentration and quality on critical indices for the formation of CaOx uroliths. Three diets with a high protein quality (10–11 % greaves meal/diet) and a varying crude protein (CP) concentration (35, 44 and 57 % in DM) were compared. Additionally, the 57 % CP diet was compared with a fourth diet that had a similar CP concentration (55 % in DM), but a lower protein quality (34 % greaves meal/diet). The Ca and oxalate (Ox) concentrations were similar in all diets. A group of eight cats received the same diet at the same time. Each feeding period was divided into a 21 d adaptation period and a 7 d sampling period to collect urine. There were increases in urinary volume, urinary Ca concentrations, renal Ca and Ox excretion and urinary relative supersaturation (RSS) with CaOx with increasing dietary protein concentrations. Urinary pH ranged between 6·34 and 6·66 among all groups, with no unidirectional effect of dietary protein. Lower renal Ca excretion was observed when feeding the diet with the lower protein quality, however, the underlying mechanism needs further evaluation. In conclusion, although the observed higher urinary volume is beneficial, the increase in urinary Ca concentrations, renal Ca and Ox excretion and urinary RSS CaOx associated with a high-protein diet may be critical for the development of CaOx uroliths in cats

Seed Mucilage Improves Seedling Emergence of a Sand Desert Shrub

The success of seedling establishment of desert plants is determined by seedling emergence response to an unpredictable precipitation regime. Sand burial is a crucial and frequent environmental stress that impacts seedling establishment on sand dunes. However, little is known about the ecological role of seed mucilage in seedling emergence in arid sandy environments. We hypothesized that seed mucilage enhances seedling emergence in a low precipitation regime and under conditions of sand burial. In a greenhouse experiment, two types of Artemisia sphaerocephala achenes (intact and demucilaged) were exposed to different combinations of burial depth (0, 5, 10, 20, 40 and 60 mm) and irrigation regimes (low, medium and high, which simulated the precipitation amount and frequency in May, June and July in the natural habitat, respectively). Seedling emergence increased with increasing irrigation. It was highest at 5 mm sand burial depth and ceased at burial depths greater than 20 mm in all irrigation regimes. Mucilage significantly enhanced seedling emergence at 0, 5 and 10 mm burial depths in low irrigation, at 0 and 5 mm burial depths in medium irrigation and at 0 and 10 mm burial depths in high irrigation. Seed mucilage also reduced seedling mortality at the shallow sand burial depths. Moreover, mucilage significantly affected seedling emergence time and quiescence and dormancy percentages. Our findings suggest that seed mucilage plays an ecologically important role in successful seedling establishment of A. sphaerocephala by improving seedling emergence and reducing seedling mortality in stressful habitats of the sandy desert environment

Effects of variations in sodium and crude protein concentrations as well as protein quality in a diet on urine composition of healthy cats

Ziel dieser Arbeit war es, die Auswirkungen des Natrium- und Rohproteingehalts sowie der Proteinqualität im Futter auf die Harneigenschaften von Katzen zu untersuchen und mögliche Risikofaktoren einer Kalziumoxalatsteinentstehung zu ermitteln. Hierzu wurden insgesamt 7 Diäten mit variierenden Gehalten an Natrium (0,38 %, 0,65 %, 1,14 % und 1,43 %), Rohprotein (34,7 %, 43,8 % und 57,4 %) und Griebenmehl (12 % und 35 %) in jeweils dreiwöchigen Adaptations- und einwöchigen Bilanzperioden an 8 gesunde Katzen verfüttert. In den Bilanzperioden wurden die Katzen einzeln in Stoffwechselkäfigen gehalten, um den Harn und Kot der Tiere quantitativ zu sammeln. Zudem wurde die tägliche Futter- und Wasseraufnahme der Katzen ermittelt. Im Harn wurden die Konzentrationen an Anionen und Kationen sowie der pH-Wert gemessen. Anhand dieser Daten konnte zudem die relative Übersättigung des Harns mit Kalziumoxalat und Struvit rechnerisch ermittelt werden. In den Kotproben wurden die Trockensubstanzgehalte sowie die Konzentrationen an Rohnährstoffen und Mineralstoffen bestimmt. Die wichtigsten Ergebnisse der vorliegenden Untersuchungen sollen nachfolgend kurz dargestellt werden. Mit steigenden Natriumgehalten im Futter konnte ein erhöhtes Harnvolumen sowie eine verstärkte renale Ausscheidung von Natrium bei den Katzen beobachtet werden. Die Kalziumkonzentration im Harn wurde nicht beeinflusst, jedoch stieg die renale Ausscheidung von Kalzium mit zunehmendem Natriumgehalt in der Ration von 0,62 auf 1,05 mg/kg Körpermasse/Tag an. Die Konzentrationen an Oxalat, Zitrat, Phosphor und Kalium im Harn nahmen hingegen mit steigendem Natriumgehalt in den Diäten ab. Die pH-Werte des Harns lagen bei Einsatz der Versuchsdiäten zwischen 6,33 und 6,45 (P > 0,05). Der Natriumgehalt im Futter hatte keinen Einfluss auf die relative Übersättigung des Harns mit Kalziumoxalat. Somit konnte dieser Studienteil einige vorteilhafte Auswirkungen einer kurzzeitigen hohen Natriumaufnahme bei Katzen vor dem Hintergrund der Kalziumoxalatsteinentstehung aufzeigen. Insbesondere die Tatsache, dass die Kalziumkonzentrationen im Harn sowie die relative Übersättigung des Harns mit Kalziumoxalat unverändert und die Oxalatkonzentrationen im Harn reduziert waren, könnte zur Prävention von Kalziumoxalatsteinen beitragen. Mit zunehmendem Rohproteingehalt im Futter konnte ein Anstieg des Harnvolumens, der Kalziumkonzentrationen im Harn, der renalen Kalzium- und Oxalatausscheidung sowie der relativen Übersättigung des Harns mit Kalziumoxalat festgestellt werden. Der pH-Wert des Harns lag bei allen Gruppen zwischen 6,34 und 6,66, wobei kein unidirektionaler Einfluss des Rohproteingehalts im Futter beobachtet werden konnte (P > 0,05). Mit Ausnahme des gesteigerten Harnvolumens sind diese Effekte einer proteinreichen Fütterung für die Prophylaxe von Kalziumoxalatharnsteinen bei Katzen insgesamt als kritisch zu bewerten. Bei Fütterung der Diät mit dem höheren Anteil an Griebenmehl konnte eine geringere renale Kalziumausscheidung bei den Katzen nachgewiesen werden. Die Ursache dieses Effekts sollte in weiterführenden Studien näher untersucht werden. Um belastbare Fütterungsempfehlungen zur Prävention von Kalziumoxalatharnsteinen aussprechen zu können, sollten die Ergebnisse dieser Arbeit in weiterführenden Untersuchungen an prädisponierten oder erkrankten Katzen überprüft werden.This study aimed at investigating the effects of variations in sodium and crude protein concentrations as well as protein quality in a diet on urine composition of cats. In particular, risk factors for the formation of calcium oxalate urine stones were evaluated. For this, seven experimental diets were fed to 8 healthy adult cats. Diets varied in concentrations of sodium (0.38 %, 0.65 %, 1.14 % and 1.43 % in dry matter), crude protein (34.7 %, 43.8 % and 57.4 % in dry matter) and collagen-rich greaves meal (12 % and 35 % in the diet). Each diet was fed for a three-week adaptation period and a subsequent one-week collection period. For the collection periods, cats were housed individually in metabolic cages to collect their urine and faeces. Feed and water intake were recorded daily during the collection periods. Concentrations of urinary anions and cations, relative supersaturation of the urine with calcium oxalate and struvite as well as faecal dry matter, crude nutrient and mineral concentrations were determined. The key findings of this study are briefly listed below. Increasing levels of dietary sodium were associated with an enhanced urine volume and renal sodium excretion. The concentration of calcium in the urine of the cats was not affected, but the urinary excretion of calcium increased from 0.62 to 1.05 mg/kg body weight/day with increasing dietary sodium levels. Urinary oxalate, citrate, phosphorus and potassium concentrations decreased at higher sodium intakes. The pH of the urine ranged between 6.33 and 6.45 among the treatment groups (P > 0.05). The relative supersaturation of the urine with calcium oxalate was not affected by varying sodium levels in the experimental diets. Consequently, in the context of the formation of calcium oxalate urine stones, this part of the study shows some positive effects of a high sodium intake in cats over a short time. The concentrations of calcium in the urine as well as the relative supersaturation of the urine with calcium oxalate remained unaffected and the concentrations of oxalate in the urine were reduced. This finding could especially contribute to prevent the formation of calcium oxalate urine stones. With increasing concentrations of crude protein in the diet, an enhanced urine volume could be observed as well as an increase in urinary calcium concentrations, renal calcium and oxalate excretion and relative supersaturation of the urine with calcium oxalate. The pH of the urine ranged from 6.34 to 6.66 among all groups, while no unidirectional influence of the dietary protein level could be detected (P > 0.05). With the exception of the enhanced urine volume, these effects of a high protein diet might be critical with regard to the prevention of calcium oxalate urine stones in cats. When feeding the diet with a higher percentage of collagen-rich greaves meal, less urinary excretion of calcium could be detected.The reason for this effect remains unclear and should be investigated in future studies. To be able to give reliable feeding recommendations for the prevention of calcium oxalate urine stones, the results of the present study should be verified through further investigations in cats that are either predisposed or diseased