Investigations on the effect of maternal dietary riboflavin supplementation during gravidity and lactation on riboflavin concentrations in blood,liver, and total body of rat offspring

The present study investigated the effect of various maternal dietary riboflavin supplementations during gravidity and lactation on riboflavin concentrations in blood, liver, and total body of their offspring. Therefore, two experiments with a total of 154 female rats were conducted. In the first experiment the animals received a semisynthetic diet (basal riboflavin concentration of 0.9 mg/kg diet) with various riboflavin supplementations during lactation (0, 2, 4, 6, 8, 10, 12, 40, 400, 4000 mg riboflavin/kg diet). In the second experiment, during gravidity, the rats were fed supplements of 1 or 20 mg riboflavin/kg diet. After parturition each group was divided into three subgroups that received 1, 5 or 20 mg riboflavin/kg with their feed during the following lactation. Both investigations continued until the 14th day of the lactation period just before the pups would start to eat the diets. The total body weights of the offspring in the first experiment only showed an effect of the riboflavin supplementation during lactation in the riboflavin‐deficient group (supplementation of 0 mg/kg diet). Regarding the second experiment, the total body and liver weights of the offspring on the 14th day of lactation were not significantly influenced by the various maternal riboflavin supplements during gravidity and lactation. The data of the first experiment clearly show that there exists a slight dose‐response relationship between the maternal dietary riboflavin supplementation during lactation and the riboflavin concentration in the blood and total body of the offspring. However, a riboflavin supplementation over 8 mg/kg diet led to a saturation of the riboflavin concentration in the body. Also, a dietary supplementation above 2 mg riboflavin/kg diet had no influence on the liver riboflavin concentration. The second investigation showed that the riboflavin concentration in all samples was influenced predominantly by the maternal riboflavin supply during lactation. The riboflavin supply during gravidity had no or only a very slight effect on the riboflavin concentrations in blood, liver, and total body of the offspring. In conclusion, these results indicate the necessity of a sufficient maternal dietary riboflavin supply (8–9 mg/kg diet) during lactation in regard to the health of their offspring and that a high riboflavin supply during gravidity cannot compensate for a deficient supply during lactation.     

The effects of diet,slaughter weight and docking on growth,carcass composition and meat quality of fat-tailed Barbarine lambs. A review

This review summarises the main factors that influence meat production and quality in fat-tailed Barbarine (FTB) lambs. As a general feature, FTB lamb's growth is moderate, and the average daily gain ranges between 100 and 350 g. The carcass being relatively fatty, carcass fat content varies from 10% to 32%; white fat and rose meat are often dominant in these carcasses. The meat fatty acid profile of this fat-tailed breed is similar to that of thin-tailed ones, with a prevalence of palmitic, stearic and oleic acids. The order of dissected adipose tissues accumulation, estimated by allometry coefficients, is in agreement with observations in thin-tailed sheep. However, tail fat allometry coefficient is closer to kidney fat values rather than to the subcutaneous one. Concerning effects of feed level, growth of FTB lambs fed silage is higher than those fed oat hay. With moderate concentrate supply, FTB lambs' growth is more pronounced on pasture diet than on the feedlot (FL) diet. Furthermore, at similar slaughter weights, carcasses of lambs fed pasture diet have less tail and carcass fat than those from lambs fed FL diet (5% and 18% vs. 9% and 24% for grazing and FL lambs, respectively). No difference in fat colour, fat firmness or cooked meat flavour is observed between carcasses obtained at different slaughtering weight (i.e. from 25 to 35 kg). The tail docking of FTB improved lambs' growth particularly before weaning. Its effect on carcass composition and fat proportion depends on stage of slaughtering and type of fattening diet. For suckled lambs (4 months), the docking resulted in the lower carcass fat weight (and proportion), while for fattened lambs, carcass composition was similar for all types of lambs. Overall, FTB lambs always grow slower than Noire de Thibar lambs. This is particularly pronounced during the fattening phase. Then, for FTB breed, the possibilities to obtain heavy carcasses are at risks of fat accumulation, 22.8% vs. 14.4% for FTB and Noire de Thibar thin-tailed lambs, respectively. However, the main advantage of FTB breed is that adults are well adapted to food scarcity and may produce lambs even under harsh conditions.     

Nutritional Programming of Intrauterine Development: A Concept Applicable to the Horse?

Human epidemiological observations and studies of experimental animals have shown that low birth weight is associated with adult phenotypes characterized by abnormalities in cardiovascular, metabolic, and endocrine function. In human populations, these changes can lead to overt degenerative diseases such as hypertension and type 2 diabetes. Because fetal growth depends primarily on the nutrient supply, the associations between birth weight and adult phenotype have been linked to poor nutrition in utero. The fetal supply of nutrients and oxygen depends on both the availability of these substances in the mother and the functional capacity of the placenta to supply them to the fetus. This review takes a comparative approach to examining the nutritional programming of adult physiological phenotype in mammals with emphasis on the horse where possible. It considers the role of maternal nutritional state and placental function in these processes and discusses the cellular and molecular mechanisms operating in utero that are responsible for the epigenetic regulation of phenotypical diversity.     

The course of phosphorus excretion in growing pigs fed continuously increasing phosphorus concentrations after a phosphorus depletion.

A balance study was performed in order to quantify the effect of continuously increased phosphorus (P) intake on faecal and urinary P excretion. The aim was to quantify the level of intake where regulatory P excretion becomes relevant for comparative digestibility measurements on P, and when the pig adapts its urinary P excretion to increased P intake. Phosphorus intake of growing pigs was continuously increased on a daily basis starting at a marginal level and P excretion via faeces and urine was continuously followed for 92 days. Two semi-synthetic diets were prepared with different proportions of Na2HPO4 resulting in 2.4 (diet 1) and 6.3 (diet 2) g P/kg DM. Concentration of Ca was adapted to achieve a Ca supply approximately 3.1 fold the digestible P supply. Six castrated male crossbred pigs (31 kg BW) were kept individually in metabolism crates after they had undergone a 14 d P depletion period during which they were fed diet 1 solely. Pigs received 1.04kg of diet 1 per day throughout the experiment, and each day the amount of feed and P supplied to pigs from diet 2 was increased by 12 g and 69 mg, respectively. ME supply was approximately 2.4 fold maintenance and average daily BW gain of pigs during the entire experiment was 690 +/- 30 g. While intake increased linearly, faecal excretion of P and Ca increased non-linearly and could be best described by third order polynomial functions. The proportion of ingested P not excreted via faeces followed a quadratic type of curve with a maximum of 81% at 25 days on experiment and P intake of 4.0 g/d. Thereafter, the proportion decreased continuously. The digestibility of P from diet 2, determined by the slope ratio technique, was constant and not affected by P intake up to a P intake of 5 g/d. Renal P excretion did not exceed inevitable losses until day 60 and increased exponentially thereafter when body P reserves were restored. It is concluded, that an adaptation to surplus P supply occurred earlier on the intestinal than on the renal level. While faecal P excretion appeared regulated depending on the actual requirement for P retention, the regulation via urine depended on the P status of the pig. Once the renal P excretion of growing pigs exceeds a level of 25 mg/d, intake of digestible P cannot be regarded sufficiently low to measure P digestibility as a capacity of the feedstuff.     

The role of experience in the development of selective zinc intake in pullets

Selective food intake behaviour was studied in pullets that were subjected to different zinc supply in early life. During the first four weeks post-hatching three groups, totaling 72 birds, were fed either a low zinc diet (25 ppm), a complete diet (50 ppm) or both diets in a choice situation. The prior feeding experience was investigated during the subsequent ontogenetic development in two-choice dietary tests. Chicks first exhibited a preference for the high zinc diet as deficiency symptoms can be seen in depleted birds. Juvenile pullets did not prefer any diet for the duration of experimental period. Layers were initially indifferent to the supplemented zinc diet, but after reaching high laying capacity they began preferentially to select the complete diet. The results indicate that early experience with diets different in zinc content have no influence on subsequent diet preferences at choice. The ability to select is based on association learning following ingestion. A conditioned diet aversion first developed in phases of high zinc requirement as a result of negative feedback mechanisms produced by the deficient diet.     

The effect of inulin supply to high‐fat diet rich in saturated fatty acids on pork quality and profile of sarcoplasmic protein in meat exudate

The aim of the study was to evaluate the influence of inulin supply to high‐fat diet rich in saturated fatty acids (SFA) on pork quality and profile of sarcoplasmic protein in drip loss. At 50 days of age, twenty cross‐bred pigs (gilts) were randomly allotted to four groups: the control (C) group fed a standard diet, and three experimental (D1, D2 and D3) groups fed a high‐fat diet rich in SFA. Moreover, pigs from the groups D2 and D3 consumed an extra inulin supply (7% of daily feed intake) from 85 to 120 days of age (for 5 weeks) and from 50 to 120 days of age (for 10 weeks) respectively. The addition of inulin to the diet reduced meaty odour and flavour significantly, improved tenderness and overall sensory quality of pork and additionally influenced ultimate pH, L* colour parameter, lactate level and protein content in meat. The diets also affected the profile of sarcoplasmic proteins. Significant effects were observed for the following enzymes—PK/PGI (pyruvate kinase/phosphoglucose isomerase) and ALD (aldolase), which are related to the intensity of post‐mortem glycolysis. Presented data indicate that long‐term inulin supply to high‐fat diet has a positive effect on technological and sensory quality as well as protein profile of pork.     

An energetic basis of equine performance

Although different physiological and behavioural attributes are needed for various types of equine competition, successful racing depends primarily on the animal's metabolic ability to convert chemical energy to mechanical energy--the function of muscle. Components of these energetic processes include the rate, efficiency and interaction of aerobic and anaerobic metabolism in muscle and the supply and utilisation of fuel. In anaerobic work like racing, fatigue processes may be largely regarded as a function of an intramuscular fuel (phosphogen) depletion, despite the fact that substrates are supplied via the circulation. Physical work capacity in the horse depends then mainly on the rate of aerobic metabolism and the capacity of the anaerobic processes to supply energy for continued muscle contraction. Underlying these processes are physiological limitations of the cardiovascular system and the ultrastructure and biochemistry of muscle. A model is proposed whereby prediction of equine performance is based entirely on parameters of energy metabolism.     

Effect of various protein levels in the diet on the activity of some metalloenzymes

Studies on the effect of increasing protein levels in the diet (0 to 50% casein) on hematological criteria (v. Krziwanek et al., 1978) were supplemented by experiments regarding the reaction of catalase, ceruloplasmin and alkaline phosphatase under such conditions. A relationship was found between the activity of all 3 enzymes and protein supply. The catalase activity of the blood revealed a linear relationship with the protein level of the diet. The activity of the alkaline phosphatase was found to go up as the protein level of the diet increased reaching its maximum with weight development. The ceruloplasmin activity revealed an opposite behaviour. The results show that the application of these criteria for measuring the supply with and conversion of trace elements do not allow reliable statements but under constant experimental conditions. The catalase activity in the blood may give certain clues for assessing the quality and quantity of protein in the feed.     

Studies on the tryptophan requirement of lactating sows. Part 2: Estimation of the tryptophan requirement by physiological criteria

Mature sows were fed for a total of 72 lactations with diets which provided an adequate supply of energy and nutrients except for tryptophan (Trp). By supplementing a basal diet [native 1.2 g Trp/kg, equivalent to 0.8 g apparent ileal digestible (AID) Trp or 0.9 g true ileal digestible (TID) Trp] with L-Trp, five further diets (2-6) containing 1.5-4.2 g Trp/kg were formulated. The dietary Trp content had no effect on amino acid contents in milk on days 20 and 21 of lactation, but Trp in blood plasma on day 28 of lactation reflected the alimentary Trp supply with an increase from 2.74 +/- 1.14 mg/l (diet 1) to 23.91 +/- 7.53 mg/l (diet 6; p < 0.001). There were no directional differences between the diets with regard to the other amino acids. Concentrations of urea in milk and blood were higher with diet 1 (211 and 272 mg/l, respectively) than with diets 3-6 (183 and 227 mg/l, respectively). Serotonin levels in the blood serum were lower with diet 1 (304 ng/ml) than the average of diets 4-6 (540 ng/ml). This study confirms previously given recommendations for the Trp content in the diet of lactating sows, estimated by means of performance, of 1.9 g AID Trp (equivalent to 2.0 g TID Trp; approximately 2.6 g gross Trp) per kg diet.     

High versus low protein diets to mink--postprandial plasma urea and creatinine response, osmotic load and pattern of nitrogen and electrolyte excretion.

Nitrogen balance, pattern of excretion of nitrogenous end-products, endogenous urinary N excretion, postprandial plasma urea and creatinine, osmotic load, urinary electrolyte excretion and water intake/output relationships were studied in 12 adult female mink fed a high protein diet (HP; n = 6) providing about 155 g protein/kg or a low protein diet (LP; n = 6) providing about 95 g protein/kg. Two balance periods of each 3 d were used and diets were fed raw or cooked. After the last balance period followed a 48 h fasting period. Postprandial plasma urea and creatinine were studied for 48 h following a test meal given after an overnight fast. Osmotic load was determined based on collection of non-acidified urine carried out during 48 h. Level of protein supply did not affect N balance, being close to zero, whereas slightly negative balances were achieved for fasting animals. Protein supply was clearly reflected in excretion of urinary urea and allantoin but not in creatinine and uric acid. Endogenous urinary N excretion was estimated by a second order regression equation giving an intercept of 280 mg/kg0.75. Post-prandial plasma urea concentrations were strongly influenced by protein supply, HP animals having substantially higher peaks than LP animals, but values returned to fasting values within 24 h after the test meal. Plasma creatinine followed a biphasic pattern with a peak about 2 h after feeding and a nadir approximately 6 h after feeding. Physical form of diet influenced postprandial urea, animals fed raw diets having a higher peak, but not creatinine. The HP diet provided almost the double osmotic load of the LP diet and a corresponding increase in urine volume. The resulting water balances were identical irrespective of diet, showing that water intake/output relationships are very accurately regulated.     

营养对兔肉品质的影响

兔肉质量很大程度上取决于家兔营养。综述了日粮能量、限饲、纤维含量、蛋白质、脂肪和抗氧化剂对兔肉品质的影响,以及日粮对兔肉安全的影响。     

Vitamin B1 content of liver, brain and muscles of pregnant and nonpregnant rats with different vitamin B1 supplies

The purpose of this publication was to examine the effects of a wide variation of dietary vitamin B1 supply (0-12,000 mg vitamin B1 per kg diet) to gravid and non gravid rats on their vitamin B1 content in liver, brain and muscle. The experiment was designed with 176 (2 x 11 x 8) female Sprague-Dawley-rats. Additionally, the organs and tissues were tested as criteria for requirement recommendations. The animals were sacrificed on the 20th day of gravidity of the pregnant rats. Before gravidity the vitamin-B1-contents were 4.7 micrograms/g liver, 2.5 micrograms/g brain and 1.5 micrograms/g muscle. At the end of the experiment the gravid rats had a 19 per cent higher liver content than the non gravids. With a dietary supply of 8-10 ppm vitamin B1 the liver content plateaued until about 120 ppm. Vitamin B1 concentration in brain was about 2 micrograms/g and gravidity was of no effect. Vitamin B1 concentration in muscle was significantly influenced by both factors and saturation was reached at 1.3 and 1.7 micrograms/g muscle. These data showed that the response of the liver to dietary supply was the most sensitive and should therefore be considered in requirements. The requirement for non gravid animals is therefore 4 mg vitamin B1 per kg diet at minimum, gravid animals should be supplied by 7 mg per kg diet.     

Effect of the manganese content in laying hen feed with different Ca and mineral levels on the egg shell quality and bone mineralization of hens]

Four experiments with 270, 44, 432 and 66800 Leghorn hens were carried out to investigate the influence of various Mn additions to diets differed in mineral or Ca contents on egg shell quality. The addition of 300 mg Mn/kg diet improved significantly egg shell breaking strength by 4 N over one year. The supply of 50-500 mg Mn/kg diet for 10-24 weeks of the second half of laying year did not influence the egg shell quality. Addition of mineral mixture or Ca grit to layer rations with adequate or higher Mn levels did not influence egg shell strength. High mineral content in a low manganese diet increased number of cracks by 3%. Strength, weight and ash content of tibia were significantly reduced by feeding a low mineral level. Addition of 50-150 mg Mn per kg low mineral diet normalized partially tibia stability in young hens. It was concluded that supplied dietary Manganese influences calcification positively only in young hens. High levels of Ca did not influence the effects of Mn. 50 mg Mn per kg layers mixture have been considered as an essential supply.     

Diagnosis and management of malabsorption in dogs

Malabsorption can result from interference with either the degradation or absorption phases in the handling of dietary constituents and represents an important cause of weight loss and diarrhoea in dogs. Effective treatment depends on identification and understanding of the underlying disease which could affect the functional capacity of the exocrine pancreas or small intestine. Exocrine pancreatic insufficiency (EPI) can be identified by a low concentration of trypsin-like immunoreactivity in serum and results in serious malabsorption due to interference with degradation of carbohydrate, protein and fat. Treatment with oral pancreatic extract complemented by a low fat, high quality protein diet, is effective in many cases. Refractory cases may need additional treatment with an oral antibiotic for small intestinal bacterial overgrowth (SIBO), and H₂-receptor blockers to help prevent denaturation of the pancreatic extract by stomach acid. The pancreas plays a key role in the normal absorption of cobalamin (vitamin B₁₂) in dogs and malabsorption of cobalamin in EPI may not resolve with treatment so that cobalamin may need to be given parenterally. Small intestinal disease may result in interference with the number or functioning of individual enterocytes, in some cases accompanied by cellular infiltration of the mucosa. Diagnosis depends on indirect assessment of intestinal damage, for example by assay of serum vitamins and determination of intestinal absorption and permeability, and in selected cases followed by endoscopic examination, intestinal biopsy and culture of duodenal juice. Treatment depends on the disease and may include oral antibiotic for SIBO and immunosuppressive drugs for infiltrative disease. Dietary management is also important, for example with a restricted fat diet containing highly digestible carbohydrate and high quality protein, and when a dietary sensitivity is suspected a restriction diet of a selected protein source may be needed.     

Assessment of dietary zinc requirement of weaned piglets fed diets with or without microbial phytase

Fifty-four pigs, weaned at 26 days of age at an average body weight of 7.74 kg were used in a 26-day experiment to assess the zinc requirement of piglets, using diets based on maize and soybean meal, with or without microbial phytase. The nine experimental diets were the basal diet containing 33 mg of zinc/kg supplemented with 10, 25, 40, 60 or 80 mg of zinc as sulphate (ZnSO(4), 7H(2)O)/kg and the basal diet supplemented with 0, 10, 25 or 40 mg of zinc as sulphate/kg and 700 units (U) of microbial phytase (Natuphos)/kg. Pigs were fed the basal diet for a 7-day adjustment period prior to the 19-day experimental period. Microbial phytase enhanced plasma alkaline phosphatase (AP) activity, plasma zinc and bone zinc concentrations. These parameters increased linearly with zinc intake, with a similar slope with and without phytase. The response of bone zinc-to-zinc added did not plateau. Without microbial phytase, plasma AP activity and zinc concentration were maximized when dietary zinc reached 86 and 92 mg/kg respectively. With microbial phytase they were maximized when dietary zinc concentration reached 54 and 49 mg/kg respectively. Accounting for a safety margin, the recommended supply of zinc for weaned piglets up to 16 kg fed maize-soybean meal diets supplemented with zinc as sulphate is thus of 100-110 mg/kg diet. This supply may be reduced by around 35 mg if the diet is supplemented with 700 U of microbial phytase.     

Effects of zinc levels on activities of gastrointestinal enzymes in growing rats

The present study investigated the effect of different zinc (Zn) levels on activities of gastrointestinal digestive enzymes of growing rats. Four diets including Zn‐adequate (ZA; 46 mg/kg, control), Zn‐deficient (ZD; 3 mg/kg), high Zn supply (ZH; 234 mg/kg) and pair‐fed in which animals received the ZA diet at restricted amounts reflecting feed intake of the ZD group were fed to rats for 5 weeks. Dietary Zn was supplemented with ZnO. The results showed that Zn deficiency resulted in decreases in body weight, while ZH supply stimulated growth. The activities of sucrase, lactase and lipase were unaffected by dietary Zn levels. Maltase activity, however, was reduced in ZD group and elevated in ZH group. Amylase and protease activities were depressed by zinc deficiency. However, rats fed the Zn‐repletion diet displayed higher activity of pepsin, pancreatic amylase and protease. In particular, ZH supply did have no effect on intestinal hydrolases activities. The present study suggested that zinc deficiency impaired the activities of digestive enzymes and growth of animals. However, ZH supply might improve the digestion of nutrients via increasing activities of gastrointestinal hydrolase and probably enhanced animal health.     

Stoichiometry of a semi‐aquatic plethodontid salamander: Intraspecific variation due to location,size and diet

Ecological stoichiometry provides a framework to investigate an organism's relationship to nutrient cycles. An organism's stoichiometry is thought to constrain its contribution to nutrient cycles (recycling or storage), and to limit its growth and reproduction. Factors that influence the stoichiometry of a consumer are largely unstudied, but what is known is that consumer stoichiometry is influenced by the elemental requirements of the consumer (e.g. for growth, reproduction and cell maintenance) and the availability of elements. We examined whole‐body stoichiometry of larval southern two‐lined salamanders (Eurycea cirrigera) and described the influence of location, body size, stoichiometry of diet items, and environmental nutrient supply on whole‐body stoichiometry. Mean composition of phosphorous was 2.6%, nitrogen was 11.3%, and carbon was 39.6%, which are similar for other aquatic vertebrate taxa. The most significant predictor of whole‐body stoichiometry was the site where the samples were collected, which was significant for each nutrient and nutrient ratio. Body size and stoichiometry of diet items were also predictors of Eurycea cirrigera stoichiometry. Our study suggests that spatial differences in environmental nutrient supply have a stronger influence on consumer whole‐body stoichiometry among similar‐sized larvae compared to life history traits, such as body size or diet.     

Glucose metabolism and regulation in lactating mink (Mustela vison)--effects of low dietary protein supply.

Eighteen lactating mink raising litters of 6 to 7 kits were fed ad libitum from parturition on diets with 32% of ME derived from protein and decreasing fat:carbohydrate ratios [high fat:low carbohydrate (HFLC): 67:1, medium fat:medium carbohydrate (MFMC): 52:16, low fat:high carbohydrate (LFHC): 37:31]. Four weeks post partum the dams were fitted with a jugular vein catheter, and the experiment started with a 3 hours fasting period, after which the dams were fed 210 kJ ME of the experimental diets. Blood samples were collected 10 and 5 min before feeding and 30, 60, 90, 120, 150 and 180 min postprandially. Two hours postprandially a single dose of 50 microCi U-14C-labelled glucose was administered to each dam and blood samples were collected 5, 10, 20, 30, 45 and 60 min after the tracer administration. Plasma concentrations of glucose and insulin 30 to 120 min postprandially were higher in dams fed the LFHC diet, than in dams fed the HFLC diet, values for dams fed the MFMC diet being intermediate. Plasma glucagon concentrations were not significantly affected by dietary treatment. The glucagon:insulin ratios decreased postprandially in all dams, the response being significant in dams fed the LFHC diet. Plasma concentrations of urea were not significantly affected by dietary treatment. Plasma FFA concentrations tended to increase postprandially in dams fed the HFLC diet. Glucose turnover rates were approximately 4.0% per min in all dams, irrespective of dietary treatment. However, the daily glucose flux was lower in dams fed the HFLC diet than in dams fed the LFHC diet, and tended to be lower than in dams fed the MFMC diet. In conclusion, a dietary protein supply of 32% of ME simultaneously with a carbohydrate supply of 16% or 31% of ME had no adverse effects on glucose homeostasis or glucose metabolism in lactating mink.     

Two Common Disorders of Captive Bearded Dragons (Pogona vitticeps): Nutritional Secondary Hyperparathyroidism and Constipation

Two common disorders of captive bearded dragons are nutritional secondary hyperparathyroidism (NSHP) and constipation. Recognizing the husbandry factors that predispose bearded dragons to these disease conditions is an important clinical skill. Treatment of NSHP is aimed at correcting husbandry deficiencies and dietary management. Treatment of constipation depends on the underlying cause but is frequently due to a lack of sufficient water in the diet and the environment.     

Nutritional strategies to combat physiological imbalance of dairy cows during early lactation: The effect of changes in dietary protein to starch ratios

Abstract

Thirty Danish Holstein cows were used to determine how cows in early lactation adapt to changes in protein to starch supply in order to manipulate metabolism to combat physiological imbalance. During weeks 4 through 6 of lactation, 10 cows were fed either a high protein to starch ratio (high) diet, 10 cows were fed a low protein to starch ratio (low) diet while 10 others continued on the control diet. During weeks 7 through 9 of lactation, all cows returned to the control diet. The diets were formulated to consist of 15.0%, 18.6% and 22.2% crude protein and 13.3%, 7.5% and 1.7% of starch for the low, control and high diets, respectively. Besides milk urea nitrogen, no other production or metabolic parameters were affected by treatment. In conclusion, manipulation of dietary protein to starch is not a potential strategy to combat physiological imbalance during early lactation.