bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the properties of New Zealand butterfat: VIII. The fatty acid composition of the milk fat of cows grazing on ryegrass at two stages of maturity and the composition of the ryegrass lipids
Authors: Hawke J. C. 
Published: June 2009

SummaryThe lipid content of short rotation ryegrass at two stages of growth was followed at weekly intervals for several months in two spring-early summer seasons. Short succulent ryegrass consisting entirely of leaf tissue contained more lipid (mean, 8·1% of the dry weight) than mature ryegrass which contained appreciable stalk (mean, 5·1% of the dry weight). The lipid from the new growth contained fatty acids with appreciably higher proportions of linolenic acid, which was balanced mainly by lower proportions of linoleic and palmitic acids.When monozygotic twin milking cows were grazed on the short rotation ryegrass grown to two stages of maturity, it was found that the fatty acid composition of the milk fat from the two groups was different. The milk fat of cows grazed on the new growth contained higher proportions of oleic acid and other C18acids, whilst the proportions of myristic and palmitic acids were lower. The total proportions of the short-chain fatty acids were not greatly different, although in the group on new growth butyric acid was present in higher proportions and hexanoic and octanoic acids in lower proportions. The higher unsaturation of the fatty acids in the milk fat of this group of cows may be related to the higher levels of unsaturated fatty acids in the young ryegrass diet and to the extent to which these unsaturated fatty acids are hydrogenated in the rumen.
The determination of citric acid in milk and milk sera
Authors: White J. C. D. , Davies D. T. 
Published: June 2009

SummaryThe accuracy of methods that utilize the colour-forming reaction between pyridine, acetic anhydride and citric acid for the determination of citric acid in milk and milk sera has been examined. A method based on that of Saffran & Denstedt (1948), in which a trichloroacetic acid (TCA) filtrate is used, gave values 3–5% low for the citric acid content of both milk and milk ultrafiltrate. The method of Merier & Boulet (1958), in which aqueous samples are analysed, gave an accurate value for the citric acid content of milk. The same technique but applied to aqueous-NaOH samples (Marier & Boulet, 1960) gave values about 7% high for the citric acid content of milk and about 3% high for the citric acid content of ultrafiltrate. However, a method using the technique of Marier & Boulet and TCA filtrate gave accurate values for the citric acid content of both milk and milk ultrafiltrate.
Lactic casein whey powder in rations for pigs: II. A comparison of un-neutralized and neutralized lactic casein whey powders with barley meal in all-meal rations for growing pigs
Authors: Dunkin A. C. 
Published: June 2009

SummaryFrom 50 to 140 lb liveweight pigs were given mixtures containing 25 or 50% of either un-neutralized or neutralized lactic casein whey powders in partial replacement of barley meal in a control ration.Those animals that were given rations containing 25 and 50% un-neutralized whey powder and 25% neutralized whey grew significantly faster and more efficiently up to 110 lb liveweight than the controls and those given the rations containing 50% neutralized whey powder. For the overall trial period, only differences between the last-named group and each of the 3 other groups that received whey powder were statistically significant.Water intake increased with level of whey powder in the diet and was significantly greater at both levels with the mixtures containing the neutralized powder than with the other diets.Carcass measurements did not indicate any significant difference in treatment.Both whey powders were sticky and unpleasant to handle, the neutralized material being worst in this respect.
A simple method for detecting an early stage in coagulation of rennetted milk
Authors: Blair G. W. Scott , Burnett J. 
Published: June 2009

SummaryAn apparatus is described which measures at 10—15 sec intervals the viscosity of rennetted milk taken from a cheese vat. The first signs of an increase in this viscosity mark what is at present the earliest measurable stage in the process of coagulation. Coagulation times so determined agreed fairly closely with the observations of a skilled cheese-maker and, for a given milk, were inversely proportional to rennet concentration over quite a wide range. Clotting times obtained by the method of Berridge (1952) for standardizing rennets came 2 or 3 min after those determined by the new method and were linearly related but not proportional to inverse rennet concentration.
The distribution and characters of coagulase-negative staphylococci of the bovine udder
Authors: Edwards S. J. , Jones G. W. 
Published: June 2009

SummaryCoagulase-negative staphyloccoci were isolated regularly over a period of 39 weeks from quarter milk samples of 18 cows belonging to one herd. They did not produce a leucocytosis in the milk or high anti-haemolysin titres in the blood of these cows, but such responses occurred in 2 cows infected with pathogenic staphylococci. The coagulase-negative variety was found to colonize the teat duct and surface of the teat in preference to the milk and possessed greater resistance than pathogenic staphylococci to certain long-chain fatty acids. Infection with coagulase-negative staphylococci was thought to antagonize the colonization of the udder by a pathogenic variety present in the herd; 23% of the coagulase-negative strains were found to elaborate an antibiotic substance inhibitory to the growth of a coagulase-positive staphylococcus. Coagulase-negative strains were characterized by the production of ɛ-toxin and could be divided into 3 main groups according to their effect on gelatin, mannitol and phenolphthalein diphosphate as substrates.
The induction of ketosis in the lactating dairy cow
Authors: Hibbitt K. G. 
Published: June 2009

SummaryInjections of l-thyroxine into normal dairy cows at the beginning of lactation resulted in animals fed on a high protein diet becoming ketotic. Some of the symptoms observed in the induced ketotic cows showed many similarities when compared with those associated with the spontaneous condition.In most cases the levels of the constituents estimated in the blood of the induced ketotic cows were similar to those measured in blood from spontaneous cases. A histological examination of the liver from an induced ketotic cow showed a considerable increase in the fat content, particularly in the centrilobular regions. The fat content of this tissue amounted to 26% with a concomitant depression of liver glycogen to only 10% of the normal level.Diet was found to play an important role in the susceptibility of cattle to the induced ketosis, since animals fed on rations containing a lower level of protein were more resistant. Attempts to induce ketosis in cows 6—8 months after calving were completely unsuccessful.The part played by the thyroxine and the diet in the induction of ketosis is discussed.
Changes in the quantity and composition of mammary gland secretion in the dry period between lactations: I. The beginning of the dry period
Authors: Wheelock J. V. , Smith A. , Dodd F. H. , Lyster R. L. J. 
Published: June 2009

SummaryThe changes in the yield and composition of the mammary gland secretion in the first 16 days of the dry period have been investigated in 6 cows. The quantity of secretion, lactose, potassium, casein, α-lactalbumin, β-lactoglobulin and fat present in the gland decreased rapidly. A decrease was also observed for sodium, chloride, residual albumin and proteose-peptone + globulin but was much less marked. Changes in composition were qualitatively similar to those normally occurring at the end of lactation but they were much more pronounced. Within 8 days after drying-off the concentrations in the secretion of sodium, chloride and potassium were similar to those of blood. There were differences between, animals in the rate at which the changes developed. As the secretory activity of the gland ceased, the constituents of the mammary gland secretion appeared to be resorbed.
Investigations on the use of the Milko-tester for routine estimation of fat content in milk
Authors: Murphy M. F. , McGann T. C. A. 
Published: June 2009

SummaryResults of studies on the operation of the Milko-tester Mark II for the estimation of fat in both herd and individual milks are presented. Milko-tester readings were compared to the means of duplicate Gerber results.It was found that, for 894 herd milks, a direct Milko-tester reading (G = M) had a standard error of estimate of ±0·071, whereas regression equation (G = 1·02 M −0·075) derived for the same data gave ±0·070. For 1133 individual milks, the equation (G = 1·03 M − 0·186) also had an accuracy of ±0·070, while the direct Milko-tester reading gave ±0·107. However, a simple subtraction of 0·077 from each Milko-tester value (i.e. G = M−0·077) for individual milks reduced the standard error to ±0·071.It is concluded that the Milko-tester is satisfactory for herd milks, particularly for milks up to 3.8 % fat. For individual milks a special regression relationship is necessary to achieve comparable accuracy.
Detection of caeruloplasmin in bovine milk and blood serum
Authors: Hanson L. Å. , Samuelsson E.-G. , Holmgren Jan 
Published: June 2009

SummaryThe copper-binding protein, caeruloplasmin, has been detected in bovine blood serum, colostrum and normal milk using immuno-diffusion techniques by comparison with a precipitating oxidase-positive system of human caeruloplasmin and anti-caeruloplasmin. The possible importance of this copper-binding protein of milk in the oxidative deterioration of milk and dairy products is discussed.
Effects of repeated heat treatments on the levels of some vitamins of the B-complex in milk
Authors: Burton H. , Ford J. E. , Franklin J. G. , Porter J. W. G. 
Published: June 2009

SummaryA study was made of the destructive effects of repeated heat processing of milk on its content of vitamin B6, vitamin B12, thiamine and folic acid. Losses of thiamine and vitamin B6 were cumulative, and increased with frequency and severity of heating.With folic acid, the first heat treatment potentiated the destructive effect of subsequent treatments; in contrast, the loss of vitamin B12 during in-bottle sterilization was markedly reduced by preliminary HTST pasteurization. These anomalous effects are possibly related to a specific interaction of ascorbic acid with each of these 2 vitamins.
The effect on milk yield and composition of adding the calcium salts of acetic, propionic, butyric and lactic acids to the diets of dairy cows
Authors: Balch C. C. , Broster W. H. , Johnson V. W. , Line C. , Rook J. A. F. , Sutton J. D. , Tuck Valerie J. 
Published: June 2009

SummaryThe effects, on the yield and composition of the milk of the cow, of additions to the diet of the calcium salts of acetic, propionic, butyric or lactic acids were determined in 3 change-over experiments. In all cases yield of milk was increased slightly and milk fat content was reduced; solids-not-fat (SNF) percentage was depressed by acetate and butyrate. The effects of these treatments differed markedly from those observed previously when dilute solutions of the corresponding acids were infused into the rumen, but the relative effects of the calcium salts were similar to those of the free acids. It was concluded that the specific effects of the acids were overshadowed by a more marked general effect arising from their addition to the diet as calcium salts. This was confirmed in a subsequent experiment with fistulated cows, in which the effect of an infusion of propionic acid into the rumen was compared with that of an infusion of calcium propionate and of calcium propionate given with the diet. The effect of the addition to the diet of calcium in the form of carbonate differed from that of calcium salts of the fatty acids. It was concluded that the salts were not likely to find practical use.
The effect of temperature fluctuations on the bactericidal effectiveness of continuous heat-treatment processes
Authors: Burton H. , Cocks A. M. 
Published: June 2009

SummaryIn correctly operated continuous heat-treatment plant the processing temperature is maintained at a sufficiently elevated level to give the desired thermal death rate for any micro-organisms present before treatment. This paper shows that if through imperfect operation of the plant, the processing temperature fluctuates about the required level, the chances of survival for bacteria and spores will theoretically be increased. Tabulated results show the magnitude of the effect under varying conditions and the compensating increase in processing temperature to counteract it.
The effects of dietary palmitic and stearic acids on milk yield and composition in the cow
Authors: Steele W. 
Published: June 2009

SummaryThe effects of the isocaloric replacement of starch in the concentrate by either 5 or 10% ‘stearic acid’ (85% pure) or by 10% ‘palmitic acid’ (85% pure) on the yield and composition of milk were investigated in a feeding experiment with 12 cows in mid-lactation. The concentrate mixtures were given with a high-roughage diet that supplied 4.4 kg of hay and 2·7kg of sugar-beet pulp/day.The inclusion of 5% ‘stearic acid’ in the concentrate mixture resulted in increases in the yields of milk, milk fat, solids-not-fat (SNF) and lactose and a reduction in the content of protein in the milk, whereas, when the level of ‘stearic acid’ in the concentrate was increased to 10%, there was an increase in only the yield of milk and a reduction in the contents but not in the yields of SNF and protein in the milk. The inclusion of 10% ‘palmitic acid’ in the concentrate mixture also reduced the contents of SNF and protein in the milk but produced increases in the yields of milk, milk fat and lactose and also in the content of fat in the milk.None of the dietary treatments resulted in any changes in the concentration of blood glucose.
Dietary fatty acids and the plasma phospholipids of the lactating cow
Authors: Noble R. C. , Steele W. , Moore J. H. 
Published: June 2009

SummaryCows were given either a low-fat concentrate mixture or a concentrate mixture that contained 5 or 10% ‘stearic acid’ (85% pure) or 10% ‘palmitic acid’ (85% pure). The concentrate mixtures were given with a high roughage diet that supplied 4·4 kg of hay and 2·7 kg of sugar-beet pulp/day. Blood samples were taken from the cows on each dietary treatment and the plasma phospholipids were analysed.Phosphatidyl choline accounted for 70% of the plasma phospholipids when the cows were given the low-fat diet and about 86% of the plasma phospholipids when the cows were given the diets supplemented with the fatty acids. The inclusion of the fatty acids in the concentrate mixtures decreased the relative proportions of the plasma phosphatidyl ethanolamine, sphingomyelin and lysophosphatidyl choline but the relative proportion of the plasma phosphatidyl serine remained unchanged.When the diet was supplemented with stearic acid the concentrations of 18:0 and 16:0 in the phosphatidyl choline were unaltered but the concentration of 18:1 was increased and the concentration of 18:2 was decreased. When the diet was supplemented with palmitic acid the concentrations of 16:0 and 18:1 in the phosphatidyl choline were increased and the concentrations of 18:0 and 18:2 were decreased. In contrast, the inclusion of stearic acid in the diet increased the concentration of 18:0 in the phosphatidyl serine and decreased the concentration of 16:0; the concentrations of 18:1 and 18:2 were unchanged. The fatty acid composition of the plasma phosphatidyl ethanolamine was unaffected by dietary treatment. The effects of diet on the fatty acid compositions of the phosphatidyl choline and lysophosphatidyl choline were similar. Supplementation of the diet with stearic acid increased the concentrations of 18:0 and 18:1 in the plasma sphingomyelin and decreased the concentrations of 16:0 and 18:2. The addition of palmitic acid to the diet increased the concentration of 16:0 in the sphingomyelin but it decreased the concentrations of the other constituent fatty acids.
The denaturation of α-lactalbumin and β-lactoglobulin in heated milk
Authors: Lyster R. L. J. 
Published: June 2009

SummaryThe rates of denaturation by heat of α-lactalbumin and β-lactoglobulin in skim-milk were measured by an immunodiffusion method over a wide range of temperatures. Both reactions showed an unusual temperature dependence.The denaturation of α-lactalbumin is a first-order reaction; between 90 and 155 °C the kinetic constant k1in s−1is given by the equationwhereTis the temperature in °K.The denaturation of β-actoglobulin in skim-milk is second order with respect to time, and the kinetic constant k2in 1g–1s–1is given by 2 equations, valid for different temperature ranges. Between 68 and 90 °C,Between 90 and 135 °CResults obtained by the immunodiffusion method agreed well with those found by salt fractionation of the milk proteins. The denaturation rates decreased when a specific reagent for sulphydryl groups was added, suggesting that such groups are involved in the denaturation of both proteins.
The tertiary phase of rennin action on αs- and β-caseins
Authors: El-Negoumy A. M. 
Published: June 2009

SummaryCasein, whole αs-casein and β-casein were incubated for 3 and 14 h with crystalline rennin, at pH 6·60 and 36 °C, both in phosphate buffer and in milk dialysate. Products obtained from both systems, comprising 30–83% calciumsensitive (Cas) components, gave similar patterns on starch gel electrophoresis. Whole casein and whole αs-casein were not so soluble in milk dialysate as in phosphate buffer. No significant differences in composition were observed between the Casand the calcium-insensitive (Ca1) products from the same source.The αs1-component of the Casproduct from rennin-treated whole αs-casein had faster gel mobility in comparison to the αs1-component in the Casproduct from untreated whole αs-casein. Also, αs1-casein yielded one faster-moving degradation product, while αs2,3,4appeared unaltered after 14h. The Casproduct of rennintreated β-casein also had faster mobility than untreated β-casein and yielded one faster degradation product and several minor ones of slower mobility. Arginine was the onlyN-terminal amino acid found in the Casproduct of both rennin-treated and untreated αs- and β-caseins. The arginine content increased from 3·48 and 4·98 moles/105g to 5·12 and 6·38 moles/105g in the Casproducts from rennin-treated β-and αs-caseins, respectively.
The effects of 2 methods of incorporating soybean oil into the diet on milk yield and composition in the cow
Authors: Steele W. , Noble R. C. , Moore J. H. 
Published: June 2009

SummaryIn a feeding experiment with 6 cows in mid-lactation a portion of the starch in the concentrate part of the diet was isocalorically replaced by 8% soybean oil, and the effects on the yield and composition of the milk were studied. The oil was incorporated into the diet either as coarsely ground soybeans or by direct addition of the oil itself. The concentrate mixtures were given with a high-roughage diet that supplied 5·5 kg hay and 2·7kg sugar-beet pulp/day.When the soybean oil was included in the diet either in the form of soybeans or as the oil itself there was an increase in the yields of milk, solids-not-fat (SNF) and lactose, and an increase also in the percentage of lactose in the milk. The percentage of protein, however, was decreased.When the oil was included in the form of soybeans there was an increase in the yield of fat but a decrease in the percentage of SNF in the milk.When soybean oil was included in the diet, the yield of protein was increased but the yield of fat and the percentage of fat in the milk were both decreased.With both methods of incorporating the oil there was an increase in the relative proportion of propionic acid and a decrease in that of butyric acid in the total volatile fatty acids of the rumen liquor. When the oil was added directly, but not when it was added as soybeans, there was a decrease in the proportion of acetic acid in the total volatile fatty acids. The implications of these findings are discussed.
On the mechanism of milk clotting by rennin
Authors: Green Margaret L. 
Published: June 2009

SummaryTwo possible hypotheses for the mechanism of milk clotting were tested. The results obtained constituted strong evidence against one and suggested that the second is improbable. Milk was separated into a 5-fold-concentrated casein micelle suspension and milk serum. Pre-renneting of the serum did not reduce the rate of clotting on subsequent addition to the micelle suspension whether or not the conditions were such that the para-κ-casein became extensively aggregated. Washing of casein micelles up to 3 times with milk dialysate at 23°C extracted very little casein from the micelles and did not increase the clotting time of micelles resuspended to about the same concentration as in milk. The results appear to constitute decisive evidence against the hypothesis of milk clotting proposed by Parry & Carroll (1969). S-carboxymethyl-κ-casein, S-carboxymethyl-κ-casein containing 2·5 dimethylaminonaphthalene sulphonyl residues per mole, and rennin-treated dimethylaminonaphthalene sulphonated-S-carboxymethyl-κ-casein all bound Ca to the same extent at 30°C and pH 6·5, over the range 0·5–15·3 mM-CaCl2. This adds support to existing evidence that milk clotting does not involve formation of Ca bridges between casein micelles.
A note on the growth of some micro-organisms in stored bovine colostrum
Authors: Palmer G. H. , Mudd A. J. 
Published: June 2009

SummaryChanges in the microflora and titratable acidity of bovine colostrum stored at 4 and 30 °C were monitored for 21 days. Colostrum did not inhibit the indigenous microflora, and increased titratable acidity may have accounted for the observed decrease in the numbers of Enterobacteriaceae after an initial rapid growth period.
A comparison of various methods for the estimation of solids-not-fat in milk and whey
Authors: McDowell A. K. R. 
Published: June 2009

SummaryThe total solids (TS) content of milk was estimated using freeze-drying followed by a Karl Fischer (KF) titration. The average solids-not-fat (SNF) value for 12 milks calculated from the TS results by this method was 0·003±0·039 % lower than that calculated from the TS results by the British Standard (1963) gravimetric method (BS). The average SNF value calculated from the sum of the contents of lactose anhydride, ‘total’ protein and ash was slightly higher (+0·017±0·068 %) than that obtained from the BS method.Certain modifications of the BS method for TS gave erroneous results. Heating 1 or 2 g milk at an oven temperature of 100 °C for 5 h, however, gave results agreeing fairly closely with the BS values.For lactic (starter) casein whey the average SNF content from freeze-drying and KF titration was 0·075 % higher than that obtained by following the BS procedure (for TS in milk). Average values for the sum of the SNF constituents (including lactic acid) were 0·08–0·11 % lower than those obtained from BS method.In many of the values recorded in the literature there is an unexplained discrepancy between the SNF content calculated from the sum of the constituents and that calculated from the TS content estimated gravimetrically by an alternative British Standard (1951) method. The need for a uniform method for estimating TS is stressed.