Dose Cases Research Articles

Probing the effects of increased protein intake on Plasmodium berghei parasitemia level in Swiss Webster mice

Malaria remains a significant global health challenge, with Indonesia being no exception. Upon infection, the host's immune system plays a pivotal role in combating the malaria parasite. Proteins, being essential macronutrients for supporting the immune system, hold particular significance. Therefore, this research aims to investigate the impact of supplementary protein intake on the parasitemia levels of Plasmodium berghei in Swiss Webster mice. This research followed an experimental with a Posttest-only Control Design. Swiss Webster mice were selected as the study subjects. As an adjuvant therapy, casein was administered as an additional protein intake to the subjects. The severity of the infection was assessed by measuring the parasite count per µL of blood on the final day of the research, following the Peter 4-days suppressive test protocol. The findings of this study unveiled a significant correlation between the dose of casein and the severity of the infection. Interestingly, the correlation exhibited a positive trend, which deviates from the anticipated results based on the research's theoretical framework. The presence of other variables that may have influenced these outcomes will be thoroughly explored and discussed in this article. From this result we hope it may spark some new question to bridge a new research idea in the future.

Physiological Doses of Oral Casein Affect Hepatic Glycogen Metabolism in Normal Food-Deprived Rats

In a previous study, administration of casein hydrolysate to food-deprived rats at a dose of 4 g/kg body wt resulted in an increase in portal plasma glucagon concentration. This was associated with an activation of phosphorylase a and a decrease in hepatic glycogen concentration. The present study was undertaken to determine whether similar results would be obtained with smaller doses. Doses of 1 and 2 g/kg body wt were administered to food-deprived rats. At a dose of 2 g/kg, portal plasma glucagon concentration was significantly elevated. This was associated with a slight increase in phosphorylase a activity (P < 0.05) and a 50% decrease in hepatic glycogen concentration (P < 0.01). At a dose of 1 g casein hydrolysate/kg body wt, changes in portal plasma glucagon concentration, phosphorylase a activity and hepatic glycogen concentration generally were not observed. Hepatic glucose, uridine diphosphoglucose, ATP and glucose-6-phosphate concentrations were unaffected by either dose of casein hydrolysate. The data indicate a dose-response relationship between casein hydrolysate administration and effects on glycogen metabolism in the liver. Protein-induced glycogenolysis is likely to occur when rats ingest a moderate amount of a pure protein meal.

The research of effect of diluents to the amount of pesticide residues in wine

The effect of various substances on the composition and quality of wine has been studied. Only imazalil residue was 0.35 µg/dm3, in course of use the activated coal in a dose of 300 mg/dm3 and no other pesticides were found. The pesticide residue was totally over during the next use of doses (450 & 600 mg/dm3) of the activated coal. So, the dose of activated coal of 450 mg/dm3 is sufficient to remove totally the residue of pesticide out of wine examples. The more significant dose of bentonite was 600 mg/dm3. In this case, the most affected one was imazalil. İncreasing the dose of casein from 150 mg/dm3 up to 600 mg/dm3 is observed decreasing with about 5-10 times of the different pesticide residue but these doses weren`t enough to remove the pesticide totally/ we can see show α-endosulfan (about 10 times) and pencondzolen (about 6 times) among highly affected pesticide residues. The weakest effect was PVPP and the strongest one was attributed to activated coal during the removing process of pesticides residues by diluents.

The effects goat milk yoghurt casein on malondialdehyde (MDA) level of rats (Rattus norvegicus) exposured by 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCCD)

Dioxins are a group of compounds that are poisonous (toxic) and it was a factor to trigger cancer (carcinogenic substance). The most toxic dioxin was 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Dioxins can cause health problems due to the nature of persistent and can bioaccumulate in the fat body. Casein goat milk yogurt potential as an antioxidant. This study aimed was to determine the effect of goat milk yogurt to dioxin exposure were observed in the levels of Malondialdehyde (MDA) of heart rats (Rattus norvegicus). Itwas an experimental study by used a completely randomized design (CRD). The rats (Rattus norvegicus) were divided into 6 groups, the each namely were: the negative control group (K-), control casein group (KK), the positive control group (K+), treatment 1 group (K1), treatment 2 group (K2), and treatment 3 group (K3). Heart MDA levels measured by used thiobarbituric acid (TBA) with UV-Vis spectrophotometry method at a wavelength of 530 nm. MDA heart analysed by one-way Analysis of Variance (ANOVA) confidence level α = 5%. The results showed that the best yogurt casein dose used to inhibit MDA in TCDD-rats is 900 mg/kg. Casein goat milk yogurt can prevent the increase of MDA significantly (p<0.01) as a result of exposure to TCDD. Goat’s milk yogurt casein dose of 900 mg/kg is the best dose. The conclusion is the provision casein goat milk yogurt can prevent the increase of MDA caused by exposure to TCDD.

The activity of casein derived from goat milk yogurt as an antioxidant on histopathology of rat’s liver exposure by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a toxic contaminant which persistent in the environment. Accumulation of this compound on the body through food chain can generate adverse effect in human health. The aim of this research was to observe the activity of casein derived from goat milk. A total of twenty-four male Wistar rats of twelve weeks old were used in this research. The rats were divided into six groups: (1) control group, (2) placebo group which given casein 600 mg/kgBW, (3) TCDD group given with TCDD 100 ng/kgBW, group P1 given casein 300 mg/kgBW and TCDD, (5) group P2 given casein 600 mg/kgBW and TCDD, (6) group P3 given casein 900 mg/kgBW and TCDD. Provision of casein and TCDD were given orally for 21 days. Liver sample collected for histopathological examination with hematoxylin Eosin (HE) stained. Experimental method was based on completely randomized design. The histopathological were analyzed by Kruskal-Wallis test followed by Mann-Whitney test to know the differences of the treatments. Result of the research showed that casein could protect the rat liver from damage in TCDD intoxicated rats. Significant increase (P<0.05) shows from group given with casein dose 900 mg/kgBW.

Evaluation of changes in colour properties of clarified red and rosé wines

Effects of some selected clarifying agents on the colour of red and rosé wines were investigated. Selected clarifying agents were added in various doses to young red and rosé wines. Total monomeric anthocyanins and total polyphenols were estimated in all treated wine samples, as well as the colour intensity, hues and parameters CIE L*a*b*. In accordance with our expectations, contents of anthocyanins were decreased in all samples treated with clarifying agents. The most marked loss of total monomeric anthocyanins was observed after the application of bentonite. As compared with red wine samples, the percentage losses in luminance values (i.e. in colour intensity) of rosé wines were higher and the resulting values were significantly dependent on the variety. In red wines, the content of polyphenols was very markedly decreased after the application of the highest dose of casein while in rosé wine samples the most marked decrease in the content of polyphenols was observed after the application of the preparation polyvinylpolypyrrolidon.

Flocculation of Kaolinite Suspensions in Water by Coconut Cream Casein

The flocculation of kaolinite colloidal particles was carried out at pH = 6 in suspension of initial turbidity varying between 24 NTU and 102 NTU by a casein extracted from Cocos nucifera cream. During Jar-test essays, 90% to 99% of colloids were eliminated in the sediments. The optimal doses of casein used depend on the initial colloids concentrations of the suspension and were found to be 60 mg/L and 100 mg/L respectively for suspensions having turbidity of 24 NTU and 102 NTU. The corresponding residual turbidity are respectively 2.80 NTU and 10.22 NTU for clarified water. The structural analysis of the freeze-dried sediments by FTIR shows sharp adsorption bands at 1558 cm–1 and 1653 cm–1, indicating the presence of casein in the sediment. The flocculation process between the particles of kaolinite and the coconut casein is adsorption and bridging.

Role of xanthine oxidase, lactoperoxidase, and NO in the innate immune system of mammary secretion during active involution in dairy cows: manipulation with casein hydrolyzates

The aims of this study were to test whether xanthine oxidase, lactoperoxidase, and NO are components of the innate immune system of mammary secretion during active involution in dairy cows, and whether the innate immune system is activated by casein hydrolysates. Our laboratory has shown recently that infusion of CNH into mammary glands induced involution and was associated with earlier increases in the concentrations of components of the innate immune system. Intact casein is inactive and served as control. Half of the glands of 8 Holstein cows scheduled for dry off (∼ 60 days before parturition) were injected for 3 days with a single dose of casein hydrolyzates and the contralateral glands with a single dose of intact casein with the same concentration. Involution elicited marked increases in xanthine oxidase and lactoperoxidase activities, and accumulation of urate and nitrate. NO and H 2O 2 were constantly produced in the mammary gland secretion. Nitrite formed either by autooxidation of NO or by conversion of nitrate to nitrite by xanthine oxidase was converted into the powerful nitric dioxide radical by lactoperoxidase and H 2O 2 that is derived from the metabolism of xanthine oxidase. Nitric dioxide is most likely responsible for the formation of nitrosothiols on thiol-bearing groups, which allows an extended NO presence in mammary secretion. Nitrite is effectively converted to nitrate, which accumulated in the range of ∼25 μM −1 mM from the start of the experiment to the complete involution of glands. The mammary secretion in all glands was bactericidal and bacteriostatic during established involution, and this appeared sooner and more acutely in glands treated with casein hydrolyzates, within 8 to 24 h. It is concluded that xanthine oxidase, lactoperoxidase, and NO are components of the mammary innate immune system that form bactericidal and bacteriostatic activities in mammary secretions. The innate immune system play a major role in preventing intramammary infection during milk stasis and its activation may increase its effectiveness.

Effects of virginiamycin and monensin plus tylosin on ruminal protein metabolism in steers fed corn-based finishing diets with or without wet corn gluten feed.

Six ruminally cannulated steers (345 +/- 20 kg initial BW) were used in a 6 x 6 Latin square to evaluate effects of diet and antibiotics on ruminal protein metabolism. Two diets and three antibiotic treatments were arranged factorially. One diet contained (DM basis) 72% dry-rolled corn, 12% soybean meal, 10% alfalfa hay, and 4% molasses (SBM), and the other contained 63% dry-rolled corn, 30% wet corn gluten feed, and 5% alfalfa hay (WCGF). Antibiotic treatments included control, virginiamycin (175 mg/d; VM), and monensin/tylosin (250 and 100 mg/d, respectively; MT). Steers were fed at 12-h intervals at a rate of 2.4% of empty BW daily. Each period included 18 d of adaptation and 3 d of ruminal fluid collections. Samples were collected at 0, 2, 4, 6, 8, and 10 h after the morning feeding on d 19 and 20. On d 21, rumens were dosed 2 h after the morning feeding with 350 g of solubilized casein to evaluate in vivo ruminal protease and deaminase activities. Ruminal fluid samples were collected 1, 2, 3, 4, and 6 h after the casein dose. On d 19 and 20, antibiotics had no effect on ruminal pH or concentrations of VFA, lactate, ammonia, ciliated protozoa, alpha-amino nitrogen (AAN), or peptide N, but VM reduced (P < 0.01) the concentration of isovalerate compared to MT and control. After casein dosing (d 21), peptide N concentration was unaffected by antibiotics, but AAN were higher (P < 0.01) for VM than MT and control. Relative to MT and control, VM reduced ruminal isovalerate (P = 0.05) and increased ruminal propionate (P < 0.01) on d 21. Ruminal pH was lower (P < 0.01) in steers fed SBM than in steers fed WCGF, but lactate concentrations were unaffected by diet. Steers fed SBM had higher (P < 0.05) ruminal concentrations of total VFA and propionate. Ammonia concentrations were lower before feeding and higher after feeding for steers fed WCGF (P < 0.01). Steers fed WCGF had higher counts of total ciliated protozoa than steers fed SBM (P < 0.05) due to greater Entodinium sp. (P < 0.05). Steers fed WCGF had higher (P < 0.01) ruminal AAN and peptide N concentrations than those fed SBM on d 19 and 20. After casein dosing, ruminal peptide N concentrations were similar, but AAN were lower (P < 0.01) for WCGF than SBM. Overall, VM appeared to depress ruminal deaminase activity, and MT had minimal effects on ruminal fermentation products. The protein in WCGF appeared to be more readily degradable than that in SBM.

A comparison of the effects of 2 doses of soy protein or casein on serum lipids, serum lipoproteins, and plasma total homocysteine in hypercholesterolemic subjects , , ,

Studies have shown that soy protein reduces some atherogenic lipid and lipoprotein concentrations, although lipoprotein(a) concentrations may be increased. The dose response of soy protein has not been established; neither has its effect on plasma total homocysteine. Our objective was to evaluate the effect of 2 doses of soy protein on lipid, lipoprotein, and homocysteine concentrations. Four to 24 wk after being instructed to consume a lipid-lowering diet, 130 men and women with LDL-cholesterol concentrations > or = 4 mmol/L were studied during a parallel group trial in which 4 interventions were assigned randomly. Thirty grams isolated soy protein (ISP) and 10 g cotyledon fiber or 50 g ISP and 16.6 g cotyledon fiber or equivalent doses of casein and cellulose were consumed daily as a beverage for 16 wk. When the 2 groups who consumed ISP were compared with the 2 groups who consumed casein, the differences in the net changes from baseline to week 16 in the concentrations of LDL cholesterol and plasma total homocysteine were -0.26 mmol/L (95% CI: -0.43, -0.09 mmol/L; P = 0.01) and -0.8 micromol/L (-1.4, -0.2 micromol/L; P = 0.005), respectively. The effect of the ISP dose was not significant. There were no significant differences between the 2 ISP and the 2 casein groups in changes in lipoprotein(a), HDL-cholesterol, or triacylglycerol concentrations. Adding 30-50 g soy protein/d to a lipid-lowering diet significantly reduced LDL-cholesterol concentrations without increasing lipoprotein(a) concentrations. Plasma total homocysteine concentrations also decreased, suggesting a novel, possibly antiatherosclerotic effect.

Conditioned feeding responses of sheep towards flavoured foods associated with casein administration: the rôle of long delay learning

AbstractThe objective of two experiments was to investigate whether a delayed type of learning could account for the conditioned feeding responses of sheep towards novel food flavours associated with post-ingestive consequences (PIC) created from the administration at different points in time of a nutritive stimulus (casein). The doses of casein were low (15 g) and high (75 g) for experiments 1 and 2, previously known to result in positive and negative PIC respectively. Each experiment consisted of three conditioning periods, during which sheep were trained to associate one of two novel flavours with either casein or water (placebo) administration. During each conditioning, a novel flavoured food low in protein and relatively high in energy, was offered for 3 h (08:00 to 11:00 h) and was followed by an unflavoured, nutritionally similar food for the rest of the feeding time (11:00 to 17:00 h). Sheep were randomly assigned to one of three treatments that were defined by the time when casein or water doses were administered, in relation to the presence of the flavoured food (A= 08:30 and 10:00, B= 11:30 and 13:00 and С = 14:30 and 16:00 h respectively). At the end of each conditioning period preference tests were performed, where sheep were offered a choice between the two flavoured foods. There was no effect of time of casein administration on the conditioned responses towards flavoured foods in either experiment. In both experiments, the proportion of the flavoured food selected was significantly affected by the interaction between preference tests and casein association. For experiment 1 this was due to an increasing preference for the casein associated food accompanied by a decreasing preference for the water associated flavoured food as a result of repeated conditioning. The degree of such preference was different between flavours used for association with casein or water. For experiment 2 avoidance of the casein and preference for the water associated food were established after the completion of the second and reinforced by the third conditioning period. Flavours used had a lesser effect on the conditioned responses of this experiment. The results support the view that sheep develop conditioned responses towards novel food flavours associated with the administration of a nutritive stimulus, even when the PIC resulting from its administration are significantly disassociated in time from the presence of the flavoured food.

The continuum between preferences and aversions for flavoured foods in sheep conditioned by administration of casein doses

AbstractThe main objective of the experiment was to investigate whether a continuum links the development of conditioned flavour preferences and conditioned flavour aversions (CFPs and CFAs) in sheep, towards food flavours associated with intraruminal administration of increasing doses of the same nutritive stimulus: casein. A secondary objective was to investigate the effects of dose of casein administration and the number of repeated exposures to casein on the rate of establishment, magnitude and degree of persistence of developed CFPs and CFAs.The experiment consisted of three conditioning periods (each lasted 8 days). A food with low crude protein (CP) (39.3 g/kg dry matter (DM)) and metabolizable energy (ME) (5.3 MJ/kg DM) contents was used in combination with one of two flavours, orange and aniseed, on a total of 48 Texel × Greyface male, 3-month-old sheep. The sheep were conditioned to associate one flavour added to the test food with a particular dose of casein (C) suspended in water (8.75, 17.5, 35 and 52.5 g per animal), or a different flavoured test food with an equal amount of water. Each dose was administered by gavage through a stomach tube twice daily to each animal. At the end of each conditioning period the preference for the two flavours was measured by a two choice preference test between the two flavoured test foods for 40 min. After the completion of the last conditioning period, three more preference tests (persistence tests), without any intervening exposure to the flavoured test food, were conducted at 7, 21 and 35 days. Preference for the flavoured test food paired with casein was affected by the interaction (P&lt; 0·001) between the dose of casein and casein association respectively. Association with casein (DPR: intake of a flavoured test food paired with casein per g total intake of flavoured test foods during the preference test) led to CFPs (DPR &gt; 0·70) at the two lowest and to CFAs (DPR &lt; 0·30) at the two highest doses. CFPs and CFAs were established by the second conditioning and there was no difference in the rate of establishment between preferences and aversions. The persistence tests showed a strong and similar degree of persistence of both formed CFPs and CFAs, since these were not affected by time of persistence test or by any of the interactions with time. In view of these results a model is proposed which could account for the conditioned responses of sheep towards administration of increasing doses of the same nutrient. The existence of a continuum between CFPs and CFAs created by the same nutrient given at different doses, could be the basis of how ruminants select a diet which meets their nutrient requirements at a particular point in time and thereby avoid excess of nutrient intake.

The continuum between conditioned preferences and aversions in ruminants to flavoured foods associated with the increasing administration of casein doses

In recent years there has been an increasing interest in the question of how ruminants develop conditioned flavour preferences or aversions (CFP's, CFA's) towards food flavours associated with the administration of various substances. Several studies have shown that ruminants are able to develop CFA's when pairing a novel food flavour with the administration of secondary compounds which lead to adverse post-ingestive consequences (e.g. activation of the emetic system, hypocalcaemia, Kyriazakis et al., 1997). In addition, CFP's, can be developed through associations between the food properties and the administration of nutrients which lead to positive post-ingestive consequences (e.g. increased nitrogen supply, Villalba and Provenza, 1997). The purpose of this study was to investigate whether a continuum exists between CFP's and CFA's which are developed towards a food flavour associated with the administration of the same nutritive stimulus, given at increasing doses. In addition, the rate of establishment and degree of extinction of such food CFP's and CFA's was also investigated.

The continuum between conditioned preferences and aversions in ruminants to flavoured foods associated with the increasing administration of casein doses

In recent years there has been an increasing interest in the question of how ruminants develop conditioned flavour preferences or aversions (CFP's, CFA's) towards food flavours associated with the administration of various substances. Several studies have shown that ruminants are able to develop CFA's when pairing a novel food flavour with the administration of secondary compounds which lead to adverse post-ingestive consequences (e.g. activation of the emetic system, hypocalcaemia, Kyriazakis et al., 1997). In addition, CFP's, can be developed through associations between the food properties and the administration of nutrients which lead to positive post-ingestive consequences (e.g. increased nitrogen supply, Villalba and Provenza, 1997). The purpose of this study was to investigate whether a continuum exists between CFP's and CFA's which are developed towards a food flavour associated with the administration of the same nutritive stimulus, given at increasing doses. In addition, the rate of establishment and degree of extinction of such food CFP's and CFA's was also investigated.

Preference for flavoured foods by lambs conditioned with intraruminal administration of nitrogen.

We suggested that food preference depends on the interplay between flavour and post-ingestive effects, and we predicted that protein-restricted lambs would acquire preferences for foods paired with supplemental sources of N, including urea (Expts 1 and 2), casein (Expt 3), and gluten (Expt 4). In each experiment, twenty lambs, in two groups of ten, were conditioned as follows: on odd-numbered days, lambs in group 1 received wheat straw (Expts 1, 3, and 4) or ground barley (Expt 2) flavoured with a distinctive flavour, and lambs in group 2 received the same food but with a different flavour. On even-numbered days, flavours were switched and lambs received capsules containing different amounts of urea (ranging from 0.12 to 0.92 g N/d), casein (ranging from 0.23 to 0.69 g N/d), or gluten (ranging from 0.23 to 0.69 g N/d). After conditioning period of 8 d, lambs were given a two-choice test to determine preference for flavours paired with N. In Expts 1 and 2, lambs preferred the flavours conditioned with urea at lower doses (0.12 g N/d in Expt 1, 0.23 and 0.46 g N/d in Expt 2), but they avoided the flavour associated with urea at the highest dose (0.23 g N/d in Expt 1 and 0.92 g N/d in Expt 2). In Expts 3 and 4, lambs avoided the flavours associated with the lowest doses of casein or gluten (0.23 g N/d), but they preferred the flavours paired with casein or gluten at higher doses (0.46 and 0.69 g N/d). After conditioning, N administrations were suspended and lambs in Expts 3 and 4 were offered a choice of the two flavours at weekly intervals for 2 weeks (extinction); preferences persisted during extinction. Collectively, these results suggest that the post-ingestive effects of N in different forms and concentrations influenced the development of food preferences by lambs.

Effect of certain clarification treatments on some components of red wine composition

&lt;p style="text-align: justify;"&gt;Many authors have worked on wine clarification pointing out the advantages that it has to obtain limpid and bright wines as the consumer requires nowadays. In this work, we study the influence of the clarification done with different doses on the main polyphenols, organic acids and poliols of the Monastrell red wines made by the system of continuous vinification in the Monovar cooperative cellar from Denomination of Origin Alicante (Spain). After fermentation and after decanting, the wine was clarified in 100 litres tanks. Five different clarifiers have been used with three different doses in each one. Two days after the treatment, the wines were filtered on the earth and were then submitted to -5° for one week to eliminate the bitartrate. They were filtered over plates when the treatment was finished. Finally, before bottling they were subjected to a sterile filtration.The results show that the clarification lowers the coloring intensity up to 27 p. cent. The higher the dose, the higher the decrease. As for the shade, we noticed that there is a slight increase in each clarificated wine. The tannin content decreases up to 20 p. cent for high and average doses of casein. The treatments used lower the content in anthocyans from 5 p. cent (for lower doses of casein) to 19 p. cent (for higher doses of bentonite). As for the acids, the tartaric acid decreases with the quantity of clarifiers, the malic acid hardly changes with the treatment, the same happens with the lactic acid. For the citric acid, there is a small decrease with the clarification. The contents of glycerol decrease in all the wines, whatever clarifier is used. The contents in 2,3- butanediol of the wines hardly change with the claritication.&lt;/p&gt;

Adaptation of digestive enzymes to dietary protein, carbohydrate and fibre levels and influence of protein and carbohydrate quality inPenaeusuannameilarvae (Crustacea, Decapoda)

Resume Activity of digestive enzymes (trypsin, chymotrypsin and amylase) was studied in relation with food in Penaeus vannamei larvae first stages. Microparticles containing casein involved the decrease of soluble protein content and enzyme activities. Specific trypsin activity but not chymotrypsin was correlated (p< 1 %) to casein level between 10 and 60% in microparticles. Cellulose fibres in food seemed to have little effect on digestive enzymes. Starch, between 1 and 20% in microparticles, had no influence on specific amylase activity. The effect of different feeding conditions were also tested on growth. No clear relationship between growth and enzyme is established since only trypsin is concerned in the case of a casein dose effect in the food. The protein source (casein, gelatin, squid meal or fish protein soluble concentrate) as well as the carbohydrate quality (soluble starch, standard corn starch, amylopectin corn starch or pregelatinized corn starch) were tested. Squid meal stimulated significantly chymotrypsin activity @<2 %) while trypsin activity decreased with fish protein soluble concentrate @<5 %). Source of carbohydrate seemed very important, amylase activity increased significantly (p <2 %) with corn starch. These adaptations are not correlated to growth performances since squid meal or fish protein soluble concentrate improved lama1 development until zoe 3 substage. These results suggest a specific induction of digestive enzymes to the food quality in larvae independent of growth performances.

The effects of abomasal infusions of casein or soya-bean-protein isolate on the milk production of dairy cows in mid-lactation.

The effects of abomasal infusion of casein or soya-bean-protein isolate (SPI) on milk production were investigated in four Friesian cows in mid-lactation receiving a basal diet of grass silage and barley which supplied energy and protein considerably in excess of requirements for milk production by conventional rationing standards. Three levels of infusion were used for each protein source, the corresponding doses being isonitrogenous for each of the proteins: 100, 220 and 330 g/d for casein and 115, 230 and 345 g/d for SPI. Casein produced much greater effects on the yield of milk and milk constituents than did SPI. On the highest dose of casein, milk yield was increased by 3.5 kg/d, fat output by 15% and protein output by 36%; corresponding values for the highest dose of SPI were 1.6 kg/d, 12% and 13% respectively. Increases in the yield of milk-protein were linear for casein but for SPI there was no increase beyond the first level of infusion. It was calculated that casein infusion had a marked effect on the utilization of energy: the increases in milk production could be explained either by a channelling of an extra 12 MJ metabolizable energy (ME)/d away from body tissue synthesis and into milk synthesis or by an increase in the efficiency of utilization of ME for lactation from 0.50 on the basal diet to 0.58; the measurements made did not allow the two mechanisms to be clearly differentiated.

Physiological responses to selection for greasy fleeceweight in Romney sheep

Abstract Two studies were conducted using rams from the Massey University fleeceweight-selected (FW) and control (C) lines of Romney sheep. In the first study, conducted from April to July, nine ram hoggets from each line (mean liveweight 42.1 kg) were fed 1000 g/day protein-extracted lucerne meal for 6 weeks before being blood-sampled by jugular venipuncture. They were then assigned to one of three groups receiving 0, 30, or 60 g/day formaldehyde- protected casein in addition to the basal diet. Blood sampling was repeated after 4 weeks of casein supplementation. During the pre-casein period, FW rams exhibited lower concentrations of urea (6.1 versus 7.2 mM, SE=0.3, P < 0.05) and thyroxine (3.3 versus 4.3 μg/dl, SE = 0.5, P < 0.10) than Crams. During the period of casein supplementation, intakes of nitrogen (N) in the form oflucerne meal increased with dose of casein (from 24.8 to 26.1 g/day) but were not different between the lines. Casein supplementation also increased plasma urea concentration in a dos...

Different concentrations of chemotactic factors can produce attraction or migration inhibition of leukocytes.

Parallel tests were conducted utilizing, the capillary tube migration test and the Boyden chamber assay, in order to determine whether the decrease in leukocyte chemotaxis that occurs if overoptimal cytotaxin concentrations are applied is due to migration inhibition. Overoptimal doses of casein produced decreased chemotactic response and migration inhibition for both rabbit macrophages and neutrophils. However, guinea pig neutrophils exhibited no decrease in chemotaxis despite high casein doses. Overoptimal doses of acid-denatured anaphylatoxin produced a decreased chemotactic response and migration inhibition of neutrophils. In both assays, this agent showed no effect upon macrophages. It is concluded that a chemotactic signal at different concentrations can elicit unidirectional migration or migration inhibition. Accordingly, chemotactic leukocyte attraction could be antagonistically regulated not only by serum-derived and lymphocyte-derived migration inhibitory factors but also by high doses of the chemotactic factor itself. Thus, the Boyden chamber technique can measure both chemotactic migration and migration inhibition phenomena.