The effect of diet on lower urinary tract diseases in cats

Commercial vs Homemade Cat Diets: What you need to know

PRACTICAL RELEVANCE

A feeding plan recommendation for cats, both healthy and with disease, should include diet choice, amounts to feed and the feeding method. Diet choice can be complex owing to the abundance of products, sometimes with conflicting marketing messages, and the prevalence of information with no scientific basis. It is important to be aware of the specific challenges of both commercial and homemade diets. Moreover, a nutritional assessment is a prerequisite when recommending a diet to ensure that it is safe, appropriate for the cat's life stage and nutritious for long-term feeding.

COMMERCIAL VS HOMEMADE DIETS

There are a variety of commercial diets available, allowing considerable customisation. These products are regulated and can be tested to determine nutritional adequacy and safety, although as the industry is partly self-regulated, choice of manufacturer is important. Properly formulated homemade diets can be customised to the patient and are a good option when no commercial product that meets the patient's needs exists. Homemade diets can be an owner preference. A serious limitation is the lack of testing, potentially affecting safety and also resulting in a reliance on database information to determine nutritional adequacy. Generic homemade diet recipes (eg, sourced from the internet) have additional risks of deficiencies and imbalances, and are not recommended. Homemade diets should be devised by a veterinary nutrition specialist with consideration of both patient and owner factors.

CLINICAL CHALLENGES

Dietary misinformation, which is all too readily available on the internet, may result in owners making questionable feeding choices for their pets. A homemade diet may be requested by owners based on the perception that there are poor ingredients in commercial foods. The veterinary healthcare team needs to have good evidence-based information to present to owners about diet choice.

EVIDENCE BASE

Several decades of research on feline nutrition forms the basis for nutritional requirements and dietary recommendations. There are varying degrees of evidence regarding requirements for each nutrient, and a lack of data on the effects of different types of processing on nutrient needs.

Case Report: Application and Limitations of a Plant-Based Diet Formulated for a Cat With Feline Lower Urinary Tract Disease

A 2-year-old male castrated domestic shorthair cat was presented for recommendations for dietary management of chronic FLUTD using a strictly plant-based diet as per the stipulations of the cat's owner. The cat had a history of urethral obstruction of unknown etiology, persistent marked struvite crystalluria, and persistent inappropriate elimination. Commercial plant-based products meeting the nutritional recommendations for maintenance of adult cats with the lowest concentration of struvite precursors were identified, but the cat would not eat them. At the request of the client, a homemade plant-based diet was formulated with the intention of increasing water intake and promoting acidic, dilute urine. Urine concentration was able to be decreased somewhat and struvite crystalluria resolved, but the urine remained more alkaline than intended. The cat clinically improved and no further FLUTD episodes were reported by the client.

Effects of crude protein and sodium intake on water turnover in cats fed extruded diets

The comprehension of strategies to increase urine production may be important, especially in kibble diets to prevent urolithiasis in cats. The effects of increasing amounts of crude protein (CP) and sodium on the water turnover of cats were evaluated using the water balance (WB) method and the deuterium dilution technique. The study followed a randomized block design, with three blocks of eight cats, two cats per food type in each block, and six cats per food. Four extruded diets with different amounts of CP and sodium were evaluated (on DM basis): 28% CP and 0.58% sodium; 39% CP and 0.64% sodium; 52% CP and 0.76% sodium; and 64% CP and 0.87% sodium. Cats were individually housed in cages for 8 days to measure WB, urea excretion, and faecal and urine characteristics. Deuterium oxide was used to evaluate water turnover, and during the period cats were housed in a collective cattery. The data were analysed by an F test, and the means were compared by polynomial contrasts. The ɑ level of significance was set at 0.05. The methods were compared by Pearson correlation, and Bland and Altman analysis. The increase in the CP content elevated linearly the renal excretion of urea (p < .001), and, together with the higher sodium intake, elevated the renal solute load, which resulted in a linear increase in urine production and water intake (p < .01). The urine density, metabolic water, and faecal and insensible water losses did not differ (p > .05). The water flux increased linearly when using the deuterium method (p < .001), but the obtained values were 20.85 ± 11.11 ml/cat/day higher than those verified using the WB method (p = .001). Higher CP and sodium amounts in dry diets increased the urine production and water consumption of cats, and this can be explored as a possible option to increase urination.

Clinical-diagnostic criteria and peculiarities of treatment of urocystitis in cats

The results of a study of cats with signs of urocystitis are presented. The general principles of diagnostics based on clinical, laboratory and additional research methods are established. Clinically acute urocystitis was manifested by disorders of urination – pollakiuria, dysuria, stranguria. Some of the animals showed an increase in body temperature, pain in the bladder and tightness of the walls of the abdominal cavity. According to the results of urine study, it was observed that 43.7% of the cats with urocystitis showed an increase in relative density of the urine, a change in urine pH towards higher alkaline levels, urine residue – erythrocytes, leukocytes and microorganisms were indicated. Impurities of salt and sand were found in 58.4% of the cats. In 31.4% of the cats, urocystitis was a complication of urolithiasis. Early diagnosis, especially differential diagnosis of acute and chronic, secondary urocystitis presents difficulties. Therefore, in cases of suspected inflammatory diseases of the urinary tract, a complex examination using ultrasound of the kidneys, bladder, prostate gland (in males) and the uterus (in females) is recommended.With therapeutic purpose, sick cats (two groups of 8 animals/group) were administered: anti-microbial agent (5% solution of Enrofloxacin), spasmolytic medicinal agent – Riabal®. Animals of the second group were additionally administered the drug Cystocure (Candioli Farmaceutici). According to the instructions, the plant basis of the powder Cystocure is presented by extracts of cranberries and orange peels. These substances provide the main properties of the drug – help in resisting the bacterial colonization of the lower urinary tract and change in urine pH to the acid side. The applied therapy positively influenced the clinical condition of the cats. Their general health was improved, painful sensations during the act of urination disappeared, the quantity and frequency of diuresis normalized. On the seventh day of treatment, according to the results of the study, the urine became transparent, no microorganisms were detected. In cats of the second group, which additionally used the drug Cystocure, the amount of salts and sand decreased significantly, the pH of the urine did not exceed the recommended value of 6.4, in contrast to animals of the first group.

Evaluation of three herbal compounds used for the management of lower urinary tract disease in healthy cats: a pilot study

OBJECTIVES

Lower urinary tract disease (LUTD) occurs commonly in cats, and idiopathic cystitis (FIC) and urolithiasis account for >80% of cases in cats <10 years of age. Although several strategies have been recommended, a common recommendation is to induce dilute urine resulting in more frequent urination and to dilute calculogenic constituents. In addition to conventional therapy using modified diets, traditional Chinese and Western herbs have been recommended, although only one - choreito - has published data available. We evaluated three commonly used herbal treatments recommended for use in cats with LUTD: San Ren Tang, Wei Ling Tang and Alisma. We hypothesized that these three Chinese herbal preparations would induce increased urine volume, decreased urine saturation for calcium oxalate and struvite, and differences in mineral and electrolyte excretions in healthy cats.

METHODS

Six healthy spayed female adult cats were evaluated in a placebo-controlled, randomized, crossover design study. Cats were randomized to one of four treatments, including placebo, San Ren Tang, Wei Ling Tang or Alisma. Treatment was for 2 weeks each with a 1 week washout period between treatments. At the end of each treatment period, a 24 h urine sample was collected using modified litter boxes.

RESULTS

Body weights were not different between treatments. No differences were found in 24 h urinary analyte excretions, urine volume, urine pH or urinary saturation for calcium oxalate or struvite between treatments.

CONCLUSIONS AND RELEVANCE

The results of this study do not support the hypothesis; however, evaluation of longer-term and different dosage studies in cats with LUTD is warranted.

Use of Purina Pro Plan Veterinary Diet UR Urinary St/Ox to Dissolve Struvite Cystoliths

The objective of this study was to determine the efficacy of feeding the commercially available diet, Purina Pro Plan Veterinary Diets UR Urinary St/Ox, for the dissolution of struvite cystoliths in cats with naturally occurring disease. Twelve cats with clinical signs of lower urinary tract disease and cystoliths confirmed via radiographs were enrolled. The cats were fed the study diet ad libitum and assessed by abdominal radiographs weekly. Cats with cystoliths that resolved based on radiographs and confirmatory ultrasound examination were considered diet successes. Cats with no change in cystolith size after 2-6 weeks underwent cystotomy for stone removal, aerobic culture and antimicrobial susceptibility testing, and analysis. All cats accepted the study diet, and weight loss was not noted over the course of the study. Total cystolith dissolution was achieved by week 2 for 5 cats, which were presumed to have struvite cystoliths. All other cats underwent cystotomy for stone removal after radiographic evidence of cystoliths were still present at 2 weeks (1 cat with severe signs), 4 weeks (5 cats), or 6 weeks (1 cat). The cystoliths that were surgically removed were calcium oxalate (5 cats) and mixed (2 cats) and would not be expected to dissolve with this diet. Follow-up radiographs from 6 cats fed the diet long term (3 presumed struvite and 3 with other cystoliths removed surgically) were collected from 1 to 6 months after beginning the study and showed no evidence of cystolith recurrence. While larger case numbers are needed, these results suggest that feeding Purina Pro Plan Veterinary Diets UR Urinary St/Ox can successfully dissolve cystoliths that are likely struvite and may lessen the risk of recurrence of struvite and calcium oxalate cystoliths.

Sodium in feline nutrition

High sodium levels in cat food have been controversial for a long time. Nonetheless, high sodium levels are used to enhance water intake and urine volume, with the main objective of reducing the risk of urolithiasis. This article is a review of current evidence of the putative risks and benefits of high dietary sodium levels. Its secondary aim is to report a possible safe upper limit (SUL) for sodium intake. The first part of the manuscript is dedicated to sodium physiology, with a focus on the mechanisms of sodium homeostasis. In this respect, there is only few information regarding possible interactions with other minerals. Next, the authors address how sodium intake affects sodium balance; knowledge of these effects is critical to establish recommendations for sodium feed content. The authors then review the consequences of changes in sodium intake on feline health, including urolithiasis, blood pressure changes, cardiovascular alterations and kidney disease. According to recent, long-term studies, there is no evidence of any deleterious effect of dietary sodium levels as high as 740 mg/MJ metabolizable energy, which can therefore be considered the SUL based on current knowledge.

Factors affecting urine specific gravity in apparently healthy cats presenting to first opinion practice for routine evaluation

Evidence suggests that apparently healthy cats presenting for routine evaluation should have a randomly sampled urine specific gravity (USG) >1.035. A USG <1.035 might reflect inappropriate concentrating ability warranting further investigation. We measured the USG of 1040 apparently healthy cats presenting to first opinion practice in an observational study, using either in-clinic refractometers or measurements provided by reference laboratories, and examined factors that might affect USG. In-clinic refractometers were calibrated using distilled water (specific gravity = 1.000). The USG was >1.030 in 91% of cats and >1.035 in 88% of cats; 121 adult cats (⩾6 months old) and five young cats (<6 months old) had USGs of <1.035. Of these 126 cats, a pathological cause was identified in 27 adult cats - of these, 26 were >9 years old - but no young cats. No cause was identified in 43 adult cats, and further investigation was not pursued in 51 adult cats. Factors that affected USG included age, diet type, sex, fasting status, drinking avidity, refractometer type, and the interaction between sex and diet - increasing dietary moisture content lowered USG only in female cats. Most factors minimally affected USG. The odds of having a USG <1.035 without apparent pathology included age and dietary moisture content. Drinking avidity decreased with increasing dietary moisture content. Our results show that most apparently healthy cats presenting to first-opinion practice should have a USG >1.035. Dietary management strategies to lower USG might be less effective than anticipated, and warrant monitoring of USG to determine efficacy. Older cats with USG <1.035 are more likely to have pathological causes identified, although clinicians are more likely to examine these cats for possible pathology. A lack of stringent refractometer calibration could have caused some errors in estimates of USG by some observers, but would be unlikely to alter markedly the findings.

Effects of potassium chloride and potassium bicarbonate in the diet on urinary pH and mineral excretion of adult cats

Low dietary K levels have been associated with increasing renal Ca excretion in humans, indicating a higher risk of calcium oxalate (CaOx) urolith formation. Therefore, the present study aimed to investigate whether dietary K also affects the urine composition of cats. A total of eight adult cats were fed diets containing 0·31 % native K and 0·50, 0·75 and 1·00 % K from KCl or KHCO₃ and were evaluated for the effects of dietary K. High dietary K levels were found to elevate urinary K concentrations (P<0·001). Renal Ca excretion was higher in cats fed the KCl diets than in those fed the KHCO₃ diets (P=0·026), while urinary oxalate concentrations were generally lower in cats fed the KCl diets and only dependent on dietary K levels in cats fed the KHCO₃ diets (P<0·05). Fasting urine pH increased with higher dietary K levels (P=0·022), reaching values of 6·38 (1·00 % KCl) and 7·65 (1·00 % KHCO₃). K retention was markedly negative after feeding the cats with the basal diet (-197 mg/d) and the 0·50 % KCl diet (-131 mg/d), while the cats tended to maintain their balance on being fed the highest-KCl diet (-23·3 mg/d). In contrast, K from KHCO₃ was more efficiently retained (P=0·018), with K retention being between -82·5 and 52·5 mg/d. In conclusion, the dietary inclusion of KHCO₃ instead of KCl as K source could be beneficial for the prevention of CaOx urolith formation in cats, since there is an association between a lower renal Ca excretion and a generally higher urine pH. The utilisation of K is distinctly influenced by the K salt, which may be especially practically relevant when using diets with low K levels.

Companion Animals Symposium: dietary management of feline lower urinary tract symptoms

Experimental and clinical investigations have confirmed the importance of dietary modifications in medical protocols designed to treat and prevent feline lower urinary tract signs (LUTS). The objective of this review is to discuss common medical conditions contributing to feline LUTS and to present currently used and potential preventative dietary modifications. Feline LUTS are a set of clinical conditions with similar symptoms related to inappropriate urine elimination due to a combination of genetics, stress and frustration reactions, environment, and medical condition or conditions, for example, idiopathic cystitis, urolithiasis, urethral obstruction, and urinary tract infection. The main goals of dietary modifications to prevent LUTS are 1) promote large dilute volumes of urine, 2) decrease the relative supersaturation of urine for specific stone types, and 3) promote healthy bacterial populations in the gastrointestinal and urogenital tracts. The impact of dietary composition, including dietary moisture, protein concentration and digestibility, mineral concentrations (i.e., Na, Cl, Ca, P, and Mg), inclusion of acidifiers and alkalinizing agents, inclusion of vitamin B6, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and γ-linolenic acid, fiber concentration and characteristics, and oxalate degrading probiotics, on these outcomes is discussed, and dietary guidelines for cats are provided. Because of the complex interaction of diet composition, environment, and animal physiology, there is a need for clinical research linking current recommendations or dietary options for the treatment and prevention of LUTS with physiological outcomes (i.e., decreased relative supersaturation and LUTS recurrence). Additionally, for many recommendations (e.g., probiotic administration, EPA, DHA), extrapolation from other species was necessary. Research is needed in feline patients with LUTS on these dietary components.

A case of renal oxalosis in a 3-month-old cat raised under controlled conditions

The kidneys of a 3-month-old female cat were examined. The cat which had been raised under controlled conditions with no history of any poisoning showed progressive weight loss with increases in blood BUN and creatinine concentrations. At necropsy, both kidneys were firm in consistency with formation of focal scars. Histopathologically, widespread deposition of crystals was observed in the renal tubules (in both dilated lumina and degenerative epithelia) accompanying mild interstitial fibrosis with lymphocyte infiltration. The crystals were colorless or basophilic on the hematoxilin and eosin-stained section and could be visualized with polarized light as doubly fractile crystals. The crystals were identified as calcium oxalate crystals by histochemical examinations using von Kossa stain and alizarin red S stain under different conditions and by ultrastructural examination. Judging from the above-mentioned findings, the present renal lesion detected in an infant cat was diagnosed as renal oxalosis which was suspected to be hereditary in nature.

The distribution of several elements in cat urine and the relation between the content of elements and urolithiasis

The concentrations of elements in urine obtained from cats with urolithiasis were compared with those of healthy cats. The concentration of several elements, such as sodium (Na), phosphorus (P), sulfur (S), and potassium (K), in urine obtained from cats with urolithiasis was significantly higher than that of healthy cats. A significant correlation (p<0.01) was found between the concentration of magnesium (Mg) and that of other elements, such as P (r=0.8913), S (r=0.6817), and K (r=0.8391), in the urine obtained from healthy cats. A significant correlation (r=0.7422, p<0.05) was also obtained between the concentration of K and that of P in urine collected from cats with urolithiasis, but the slope of regression line was significantly different from that of the urine obtained from healthy cats. Other correlations observed in healthy cats were not obtained from cats with urolithiasis. However, a significant correlation between the concentration of magnesium (Mg) and that of calcium was obtained only from cats with urolithiasis. The results of the present study suggest that urinary concentrations of various elements in cats with urolithiasis are higher than those of healthy cats. Furthermore, the balance of elements in the urine of cats with urolithiasis was altered.

Effects of dietary protein content on renal parameters in normal cats

This study evaluates the effect of dietary protein content on renal parameters in 23 healthy spayed female cats. The objective was to determine if cats eating diets high in protein will have higher serum urea nitrogen (UN) and creatinine values without a detectable change in kidney function, as assessed by urinalysis. A single random cross-over design was used. Cats were fed a standard maintenance diet for at least 1 month prior to the dietary trial. They were fed in two phases. For the first phase, cats were randomly assigned to receive either a high protein [HP=46% metabolizable energy (ME)] or low protein (LP=26% ME) diet. For the second phase, cats were fed whichever diet they were not fed during the phase I period. Blood and urine samples were collected at 2-week intervals for the duration of the study (10 weeks). UN, albumin, alanine aminotransferase and urine specific gravity were significantly higher, and creatinine and phosphorus were significantly lower (P<0.05) when cats were fed the HP diet as compared to when they were fed the LP diet, although none of the mean values were found to be outside of the corresponding reference interval. Dietary intake can result in clinically significant changes in UN and statistically significantly changes in several other biochemical analytes, although all analytes are likely to remain within normal reference intervals. Therefore, an accurate dietary history is necessary to help determine if renal parameters are being influenced by diet in a particular patient.

Influence of nutrition on feline calcium oxalate urolithiasis with emphasis on endogenous oxalate synthesis

The prevalence of calcium oxalate (CaOx) uroliths detected in cats with lower urinary tract disease has shown a sharp increase over the last decades with a concomitant reciprocal decrease in the occurrence of struvite (magnesium ammonium phosphate) uroliths. CaOx stone-preventative diets are available nowadays, but seem to be marginally effective, as CaOx urolith recurrence occurs in patients fed these diets. In order to improve the preventative measures against CaOx urolithiasis, it is important to understand its aetiopathogenesis. The main research focus in CaOx formation in cats has been on the role of Ca, whereas little research effort has been directed towards the role and origin of urinary oxalates. As in man, the exogenous origin of urinary oxalates in cats is thought to be of minor importance, although the precise contribution of dietary oxalates remains unclear. The generally accepted dietary risk factors for CaOx urolithiasis in cats are discussed and a model for the biosynthetic pathways of oxalate in feline liver is provided. Alanine:glyoxylate aminotransferase 1 (AGT1) in endogenous oxalate metabolism is a liver-specific enzyme targeted in the mitochondria in cats, and allows for efficient conversion of glyoxylate to glycine when fed a carnivorous diet. The low peroxisomal activity of AGT1 in cat liver is compatible with the view that felids utilised a low-carbohydrate diet throughout evolution. Future research should focus on understanding de novo biosynthesis of oxalate in cats and their adaptation(s) in oxalate metabolism, and on dietary oxalate intake and absorption by cats.

Urethral obstruction in cats: Predisposing factors, clinical, clinicopathological characteristics and prognosis

Feline lower urinary tract diseases in general, and urethral obstruction (UO) in particular, are common clinical conditions in cats. The aims of this study were to identify risk factors for UO, to characterise clinical and clinicopathological signs, outcome and recurrence, as well as risk factors for mortality and recurrence. Eighty-two cats with UO were compared to 82 sex and time matched controls. The mean age of cats with UO was significantly lower compared to controls, while the mean body weight was higher. The proportion of indoors–outdoors cats was significantly lower in the study group compared to the control group, and the proportion of cats consuming only dry food was higher. Overall mortality was 8.5%. Ionised calcium was significantly higher in survivors compared to non-survivors, and the prevalence of hypocalcaemia was lower. Recurrence in 6 months and 2 years were 22% and 24%, respectively. Cats with recurrence had significantly lower urine pH at presentation.

Influence of the feed base excess on urine parameters in cats*

In this study the base excess (BE) was used as a method to predict the influence of the food on the urinary pH on cats. Nine cat foods (six dry and three canned) were consecutively fed to eight cats. The urine pH, volume, specific gravity and water and food intake were determined daily. The base excess [BE; mmol/kg dry matter (DM)] was calculated from the compounds in the food (BE = 49.9*Ca+82.3*Mg*+43.5*Na+25.6*K-64.6*P-13.4*Met-16.6*Cys-28.2*Cl). The BE of the tested foods was between -287.35 and 133.38 mmol/kg DM. The mean urine pH varied between 5.76 (SD = 0.13) and 7.16 (SD = 0.22). The BE correlated with the mean urine pH (pH = 6.25+0.0023*BE; r = 0.74**). The urine volume (ml/kg BW/day) correlated significantly positive with the K- (r = 0.71**) and significantly negative with the P-content (r = -0.67**), the Ca-content (r = -0.50**) followed by the Mg-content (r = -0.36**) of the food. The correlation coefficients between the anions/cations in the food and the urine pH was for K 0.36**, for P -0.61**, the Met+Cys -0.60** and Cl -0.27**. In practice the correlation between urine pH and BE would help to pre-estimate the effect of food on the urine pH and to prevent urolith formation.

Evaluation of effects of dietary carbohydrate on formation of struvite crystals in urine and macromineral balance in clinically normal cats

OBJECTIVE

To evaluate effects of dietary carbohydrate on urine volume; struvite crystal formation; and calcium, phosphorus, and magnesium balance in clinically normal cats.

ANIMALS

21 healthy adult cats (15 sexually intact males and 6 sexually intact females).

PROCEDURE

Diets containing no carbohydrate source (control diet), control plus starch, or control plus fiber were given in a 3 X 3 Latin-square design. The diets were available ad libitum in study 1 (n = 12) and given under restrictions in study 2 (9) to equalize daily intakes of crude protein among the 3 groups. Formation of struvite crystals and balance of calcium, phosphorus, and magnesium were measured.

RESULTS

Urine volume was lower in the starch group and fiber group in study 1, whereas no differences were detected among the groups in study 2. Urinary pH and struvite activity product were higher in the starch group in both studies, and the fiber group also had higher struvite activity product in study 2. In both studies, urinary concentrations of HCl-insoluble sediment were higher in the starch group and fiber group. In the fiber group, a net loss of body calcium, phosphorus, and magnesium was detected in study 2.

CONCLUSIONS AND CLINICAL RELEVANCE

Starch and fiber in diets potentially stimulate formation of struvite crystals. Hence, reducing dietary carbohydrate is desirable to prevent struvite urolith formation. In addition, a net loss of body calcium, phosphorus, and magnesium during feeding of the fiber diet suggests that dietary inclusion of insoluble fiber could increase macromineral requirements of cats.

Comparison of corn gluten meal and meat meal as a protein source in dry foods formulated for cats

OBJECTIVE

To compare the nutritional value of corn gluten meal (CGM) and meat meal (MM) as a dietary source of protein in dry food formulated for adult cats.

ANIMALS

8 healthy adult cats (4 males and 4 females).

PROCEDURE

Diets containing CGM or MM as the main protein source were each fed for a 3-week period in a crossover study. Digestibility and nutritional balance experiments were conducted during the last 7 days of each period. Furthermore, freshly voided urine was obtained to measure urinary pH, struvite crystals, and sediment concentrations.

RESULTS

Daily food intake and dry-matter digestibility were significantly higher for the MM diet. Fecal moisture content also was higher for the MM diet. Apparent nitrogen (N) absorption and N retention were higher for the MM diet, even when values were expressed as a percentage to account for differences in N intake. Urinary pH, struvite activity product, number of struvite crystals in urine, and urinary sediment concentrations were not different between diets. Retention of calcium, phosphorus, and magnesium was lower for the CGM diet, and cats lost body calcium and magnesium when fed the CGM diet.

CONCLUSIONS AND CLINICAL RELEVANCE

Meat meal was superior to CGM as a protein source in dry foods formulated for cats, because dry-matter digestibility and N utilization were higher for the MM diet. In addition, net loss of body calcium and magnesium for the CGM diet suggests that mineral requirements increase when CGM is used as a protein source.

Struvite formation, control and recovery

Recent legislation on the removal of nutrients from wastewater has led to a number of operation problems with struvite scaling. Struvite is MgNH4PO4 x 6H2O and this paper reviews the formation, control and recovery of struvite from primarily municipal wastewater and other waste streams. Treatment options for control and technologies for recovery are discussed.

Fish meal vs. corn gluten meal as a protein source for dry cat food

To compare the effects of two dietary protein sources, fish meal (FM) and corn gluten meal (CGM), fecal moisture content, nitrogen balance and urinary excretion were examined in adult cats. The dietary protein source did not cause a significant difference in daily food intake, water intake, urine volume, dry matter digestibility or urinary nitrogen excretion, but fecal moisture content was lower (P<0.02) in the CGM group. The HCl-insoluble fraction of urinary sediment tended to be higher in the CGM group (P<0.10), although urinary pH was similar in the two groups. These results suggest that CGM is comparable with FM in respect to nutritional value and the urine acidifying effect, but FM may be preferable to CGM for the prevention of constipation and struvite urolithiasis in cats.