bluuebunny/crossref_metadata_2025 huggingface dataset:
689. The effect of variations in nutrient intake upon the yield and composition of milk: III. A note on experimental methods
Authors: Burt A. W. A.
Published: June 2009

1. Data from seven winter feeding experiments with dairy cows, using 3×3 latinsquare designs and from two randomized block experiments on the supplementation of summer grazing, were used in a study of some aspects of experimental technique.

2. In the 3×3 trials the use of observations from 2 weeks instead of the last week of each period reduced minimum significant differences by 0·1 lb. milk/cow/day, and 0·06 and 0·02 mean percentage unit of fat and solids-not-fat, respectively.

3. In three out of four experiments no advantage was obtained from recording live weights on more than 1 day at the end of each period.

4. It was shown that the analysis of variance of milk yields expressed as individual differences between yield in the experimental period, and the mean of pre- and post- experimental control periods was considerably more efficient than that of yields in the experimental period, or covariance with yield in the initial control period.

5. The results were discussed in relation to the sources of error involved, and the relative efficiency of various types of experimental design.
690. An investigation of fourteen herds producing substandard milks in the East of Scotland
Authors: Edwards R. A.
Published: June 2009

1. Four hundred and sixteen individual cow samples of milk from fourteen herds were analysed for fat, total solids, crude protein, lactose and chloride.

2. Wherever possible information concerning feeding, incidence of mastitis, age of cow, stage of lactation and successful service dates was collected.

3. The milk samples were divided into normal (with 8·50% S.N.F. or over) and substandard (with less than 8·50% S.N.F.) groups.

4. The difference in S.N.F. content between the normal and substandard groups was due almost equally to a drop in lactose and protein, but with the latter playing the major part. Thus, although inadequate feeding was probably a major factor in lowering the S.N.F. in this population the fact that the lactose content was so often low was taken as indicating that mastitis was also important.

5. Breed, age of cow and stage of lactation all affected the incidence of low S.N.F. milks.

6. On average the substandard milks showed a reduced fat content as well as a lowered S.N.F. level.
710. The determination of free fatty acids in milk
Authors: Perrin Dawn R. , Perrin D. D.
Published: June 2009

An extraction-titration method is described for the determination of free fatty acids in small samples of fresh milk.

Recoveries of fatty acids added to milk ranged from 63% for butyric acid to 97% for stearic acid. For a composite sample approximating milk fat in fatty acid composition the recovery was 83%.

Interference from citric and lactic acids was not significant for reasonably fresh samples.

The method gives a higher recovery of the lower molecular weight fatty acids than is possible by earlier methods.

For titrating very dilute solutions of fatty acids α-naphtholphthalein was shown to be a more accurate indicator than phenolphthalein; it also provides a better defined endpoint.
714. The relation between the chemical composition of milk and the stability of the caseinate complex: III. Coagulation by rennet
Authors: White J. C. D. , Davies D. T.
Published: June 2009

1. The variation in the time required for the coagulation of milk by rennet and the relationship between milk composition and renneting time were examined.

2. The renneting times of herd bulk milks varied over the relatively narrow range of 3·2–5·4 min., whereas the renneting times of milks from individual cows varied from 1·4 to 12·9 min. and two did not coagulate.

3. In general, milk quick to coagulate gave a firm curd (early lactation milk) and milk slow to coagulate gave a soft curd (late lactation and subclinical mastitis milk).

4. The renneting time of milk was related to the stage of lactation of the cow. In early lactation, renneting times were short and as lactation advanced there was a progressive increase in renneting time; the increase became more pronounced towards the end of lactation.

5. The property of milk most closely related to renneting time was acidity. As pH increased from 6·4 to 7·2, there was a curvilinear increase in renneting time from 1·5 to 13 min. Titratable acidity was related to renneting time in the opposite way to pH.

6. Although milk containing a relatively high concentration of ionized calcium coagulated quickly with rennet, the renneting time of milks containing average, or less than average, amounts of ionized calcium was not related to their content of this constituent.

7. Weak relationships between the concentrations of other milk constituents and renneting time could be attributed to the interrelations of the concentrations of these constituents and pH.
721. An analysis of the performance of an ultra-high-temperature milk sterilizing plant: II. Calculation of the bactericidal effectiveness
Authors: Burton H.
Published: June 2009

The purpose of this paper is to show how the performance of a continuous heat-treatment plant may be predicted from the temperature distribution and the flow time distributions obtained as described in the first paper of this series (1), using thermal death-time characteristics appropriate to the micro-organisms of greatest importance. The calculations are carried out using the data obtained for the plant described in the previous paper, and they provide an estimate of the bactericidal effectiveness to be expected from that plant.
735. The B-vitamin content of milk in relation to breed of cow and stage of lactation
Authors: Gregory Margaret E. , Ford J. E. , Kon S. K.
Published: June 2009

1. Microbiological methods were used to measure biotin, nicotinic acid, pantothenic acid, riboflavin, ‘vitamin B6’ and vitamin B12 in milk from Guernsey, Friesian and Shorthorn cows.

2. A study was made of day-to-day variations and breed differences in the B-vitamin content of such milk. Fluctuations in each vitamin were observed from one day to the next in milk from individual cows, these variations being especially marked with biotin and vitamin B12. In addition, the variations in the mean vitamin levels of milk from cows of the same breed were generally greater than any breed difference.

3. Samples of milk from ten Friesian and ten Shorthorn cows were taken at intervals throughout one complete lactation and analysed for each of the vitamins mentioned above. The results of this study of lactational trends are presented in detail.
Autogenous toxoid vaccine in the prophylaxis of staphylococcal mastitis in cattle
Authors: Pearson J. K. L.
Published: June 2009

The use of an autogenous vaccine/toxoid in the prophylaxis of clinical and subclinical staphylococcal udder infections in a dairy herd is described. Mainly first calving cows were included in the trial, and the results are given on 25 vaccinated and 18 uninoculated control animals. Four injections of vaccine at weekly intervals were given and every 6 months a further inoculation was given with a view to reinforcing immunity.

Observations were made over a period of 2½ years and there was a significant difference in the number of heavy staphylococcal infections and clinical cases in treated and control groups during the first 18 months, only one clinical case occurring in the treated group compared with 9 in the controls. Major infections totalled 8·1% during this period compared with 1·9% in the treated cattle, total staphylococcal infections being 16·2% compared with 7% in the respective groups.

In the last 12 months of the experiment eight clinical cases occurred in the treated group compared with five in the controls. It is clear from these results compared with those for the first 18 months that the reinforcing doses of vaccine/toxoid every 6 months were insufficient to maintain immunity. Subclinical infections, however, remained at a lower level in the treated group than in the control animals.

The significance of subclinical staphylococcal infections in relation to Whiteside tests is discussed, also the possible relationship of toxoid and bacterial vaccination to actual immunity produced. Some evidence is given that the presence of blood serum antitoxin is not necessarily associated with immunity.
Further studies on unrestricted whey for fattening pigs including the effect of omitting antibiotic from the diet during the later stages of fattening
Authors: Braude R. , Mitchell K. G. , Cray A. S. , Franke A. , Sedgwick P. H.
Published: June 2009

1. Results are reported of an experiment with fattening pigs carried out under commercial conditions, to obtain further information on the comparison of all-meal feeding with meal plus unrestricted amounts of whey. In addition, the effect of omitting the antibiotic, oxytetracycline, from the diet during the latter half of the fattening period was investigated.

2. There were four treatments. (i) Meal only ad lib. up to a daily maximum of 6 lb./pig, with oxytetracycline included in the diet for the whole fattening period. (ii) As (i) but oxytetracycline included in the diet only up to an average pen live weight of 130 lb. (iii) 3 lb. meal reduced to 2 lb./pig/day by 13 weeks of age plus unrestricted amounts of whey with oxytetracycline included in the basal meal for the whole fattening period. (iv) As (iii) but oxytetracycline included in the diet only up to an average pen live weight of 130 lb.

There were five pens of nine group-fed pigs on each treatment, involving a total of 180 pigs. The pigs were on experiment from approximately 8 weeks of age to bacon weight. Comprehensive carcass measurements were made on all pigs.

3. The meal plus whey-fed pigs grew significantly slower and utilized their food significantly less efficiently than those fed meal only. They also had a significantly lower dressing percentage, but longer and less fat carcasses than the all-meal fed animals. The results are discussed in relation to those obtained in earlier experiments completed under similar conditions at the Cow and Gate farm.

4. Comparison of the efficiency of food utilization results of the all-meal and meal plus whey-fed pigs showed that 1 gal. of whey replaced approximately 0·7 lb. of meal.

5. The results showed that omission of antibiotic from the diet of either the all-meal or meal plus whey-fed pigs after they reached 130 lb. live weight, had no significant effect on growth rate, efficiency of food utilization or any carcass measurements of the pigs.

We wish to thank the Director of Messrs C. and G. Prideaux, Ltd., Bacon Curers, Motcombe, Shaftesbury, Dorset, for permission to take carcass measurements of the experimental pigs, and we are greatly indebted to Messrs K. Lawrence and P. Prideaux who most conscientiously took these measurements.
Heat resistance of lactobacilli from English Cheddar cheese
Authors: Perry K. D. , Sharpe M. Elisabeth
Published: June 2009

The heat resistance of strains of lactobacilli previously isolated from Cheddar cheese was determined using a laboratory pasteurization test and a commercial pasteurizer.

The laboratory tests showed variations in heat resistance at 140° F. for 10 sec. which were not correlated with species, but at 150° F. for 10 sec., an average of 99·55% destruction occurred with all strains.

With the commercial pasteurizer, heating at 155° F. for 17 sec. caused a 99·99999–100% destruction, whilst heating at 160° F. for 17 sec. destroyed 100% of all strains of lactobacilli tested in every case.

We wish to thank Miss H. R. Chapman and Miss A. J. W. Harrison for operating the pasteurizer.
Oestrogens in British pasture plants
Authors: Pope G. S. , McNaughton Mary J. , Jones H. E. H.
Published: June 2009

1. Four species of Medicago, six species of Trifolium and fourteen grass species, all frequently found in British dairy pastures, have been tested for oestrogenic activity by the mouse uterine weight method. Activity was detected in four, four and six species respectively.

2. It is probable that the quantity of oestrogen present in British pasture plants is insufficient to affect milk composition in cows at pasture. Some further experiments with cows are, however, suggested which might elucidate this.
Some volatile compounds in New Zealand Cheddar cheese and their possible significance in flavour formation: I. Identification of the volatile carbonyl fraction
Authors: Walker J. R. L. , Harvey R. J.
Published: June 2009

Flavour concentrates from mature New Zealand Cheddar cheese were prepared by steam distillation methods. Using 2:4-dinitrophenylhydrazine reagent the presence of carbonyl compounds in the distillate was established. By means of paper chromatography, and other methods, the following compounds were identified in the distillate: acetoin, diacetyl, acetaldehyde, acetone, 2-butanone, 2-pentanone, 2-heptanone, 2-nonanone and 2-undecanone, and their approximate concentrations in New Zealand Cheddar cheese were determined. The possible role of these compounds in the formation of Cheddar cheese flavour is discussed.

The authors gratefully acknowledge the helpful advice and criticism of Dr H. R. Whitehead and Dr W. A. McGillivray, and the technical assistance of Mr P. L. McLaughlin.
Restricted and ad lib. feeding of liquid skim-milk, with and without the addition of formalin, to fattening pigs
Authors: Mitchell K. G. , Sedgwick P. H.
Published: June 2009

Results are reported of an experiment with fattening pigs, made under commercial conditions, on the effect of adding formalin to liquid skim-milk, to delay souring, on the nutritive value of the milk given either in restricted or in unrestricted quantities.

There were four treatments: (i) Meal, fed to a scale based on live weight, plus sour skim-milk restricted to a maximum of 5¼ pints per pig per day. (ii) As (i) except that milk kept sweet by the addition of 0·15% formalin shortly after separation, was fed. (iii) Daily allowance of 2 lb meal/pig fed throughout the fattening period plus an unrestricted supply of sour skim-milk. (iv) As (iii) except that milk kept sweet by the addition of 0·15% formalin shortly after separation, was fed.

There were five pens of nine group-fed pigs on each treatment, involving a total of 180 pigs. The pigs were on experiment from about 9 weeks of age to bacon weight. Comprehensive carcass measurements were made on all the pigs, and bacon-tasting tests were made on samples of both green and smoked bacon from a number of the carcasses.

There were no significant differences between any of the four treatments in rate of growth or overall efficiency of food utilization.

Pigs given formalin-treated milk had a significantly thinner layer of back fat over the loin than those given sour milk. Although the difference was relatively small, it was apparent whether the milk was fed in restricted amounts or ad lib. and was reflected in the commercial grading results. There were no significant differences between treatments in dressing percentage, carcass length, shoulder back fat thickness, belly thickness or size of eye muscle.

No taint or off-flavour was detected in samples of green or smoked bacon from pigs fed milk to which 0·15% formalin had been added.

The feeding of liquid skim-milk in unrestricted quantities is discussed in relation to the comparative prices of meal and skim-milk.

The importance of adding the formalin to the skim-milk as soon as possible after separation, particularly during warm weather, is stressed in order that souring might be delayed for at least 1 week.
The effect of udder infections on the lactation yield of milk and milk solids
Authors: O'Donovan J. , Dodd F. H. , Neave F. K.
Published: June 2009

Data available for fifty cows mainly infected with Staphylococcus pyogenes have been analysed to determine the effects of udder infections and mastitis on milk, fat and solids-not-fat yield and on fat and solids-not-fat percentages over full lactations.

It was found that lactation yields of milk, solids-not-fat and fat were depressed by 10, 11 and 12% respectively in the presence of infection. These depressions were significant (P < 0·05). The composition of the milk averaged over whole lactations was not significantly affected (P > 0·05), although the mean solids-not-fat percentage of the milk was significantly depressed by 0·196±0·092 during the period of infection.

It is suggested that the depressions in lactation yield and changes in milk composition would have been greater in the absence of antibiotic therapy for mastitis.
Bulk feeds for milk Production: I. The influence of level of concentrate feeding in addition to silage and hay on milk yield and milk composition
Authors: Holmes W. , Arnold G. W. , Provan A. L.
Published: June 2009

Two experiments were carried out, Expt. 1 with twelve cows in a 4×4 Latin square and Expt. 2 with twenty-six cows in two groups which spent 11 weeks on the experimental rations. In both experiments hay and silage were fed ad lib. In Expt. 1 four levels of concentrate feeding were offered, 1¼, 2½, 3¾ and 5 lb/gal, and in Expt. 2 two levels, 1¼and 5 lb/gal. The levels of feeding as a percentage of Woodman's standards for starch equivalent (S.E.) ranged from 82 to 125% in Expt. 1 and from 83 to 116% in Expt. 2; for digestible crude protein (D.C.P.) the corresponding figures were 70–100% and 105–107%. When concentrate consumption increased by 1 lb dry matter the consumption of bulk feeds was reduced by 0·18–0·22 lb dry matter but the total fibre intake remained constant. Milk yield showed small but significant responses to level of feeding. Average responses per 1 lb S.E. were 0·77 lb milk in Expt. 1 and 0·61 lb milk in Expt. 2. Total lactation yields of the cows in Expt. 2 were unaffected by the experimental treatments. The production S.E. fed per gallon of milk ranged from 1·71 to 3·72 lb in Expt. 1 and from 1·92 to 3·27 lb in Expt 2. Production D.C.P. ranged from 0·37 to 0·63 lb and from 0·67 to 0·70 lb, respectively.

High levels of feeding increased the S.N.F. and protein contents of the milk but did not affect other constituents. The responses in S.N.F. were lower than in some other experiments and some cows showed no response. The results are discussed with reference to the experimental methods and also with reference to the yield responses compared with published data, and to the practical importance of the high production obtained with low usage of concentrate feeds.
Fishy flavour in dairy products: I. General studies on fishy butterfat
Authors: Pont E. G. , Forss D. A. , Dunstone E. A. , Gunnis L. F.
Published: June 2009

A distinct fish-oil or cod-liver-oil flavour appeared after storage in commercial butterfat containing, as an antioxidant, nordihydroguaiaretic acid (NDGA) and citric acid dissolved in propylene glycol. The fishy condition was reproducible in the laboratory by the combined effect of NDGA with either citric or lactic acids. The acids alone in butterfat gave oily and rather less clearly defined fishy flavours after storage.
Measurements of non-ionic iodine in the milk of dairy cows following oral administration of labelled sodium iodide
Authors: Morgan A.
Published: June 2009

It has been shown that iodine present as iodide in milk can be quantitatively removed by passing the milk through a column of an anion-exchange resin in the chloride form. Any residual iodine is present as non-ionic species which are not removed by the resin.

This technique was used to determine the non-ionic iodine in milk at various times after the oral administration of a single dose of 131I to dairy cows and also during a multiple-dose experiment. Non-ionic131I was present in milk 6 h after its administration and the fraction in this form varied considerably in milk from different cows, ranging from 1·2 to 14·5% of the total 131I content. The chemical form of the nonionic iodine was not investigated.
The colloidal phosphate of milk: III. Nature of its association with casein
Authors: McGann T. C. A. , Pyne G. T.
Published: June 2009

Removal of colloidal phosphate leads to changes in the propertics of milk of which the increased viscosity and greatly increased sensitivity to calcium salts, and the apparently diminished degree of mutual integration of the various casein fractions are the most striking. Re-introduction of colloidal phosphate restores incompletely and only in certain instances the original properties of the milk.

These observations are interpreted as favouring the conception of chemical links between colloidal phosphate and casein in milk.
The effect of feed supplements on the yield and composition of milk from cows grazing good pasture
Authors: Castle M. E. , Drysdale A. D. , Watson J. N.
Published: June 2009

Two experiments are described in which spring-calved Ayrshire cows were fed supplementary food when grazing good, leafy pasture.

In the first experiment 6 lb of a mixture of three parts bruised oats and one part flaked maize was fed daily to three groups of five cows. One group received the supplement from 1 July until 30 October, and the other two groups from 1 August and 1 September respectively. A control group received no supplement.

In no month was there any statistical difference in daily milk yield between supplemented and unsupplemented groups of cows. The group fed from 1 July gave the highest total milk yield in the period June to October, but with a return of only 1 gal of milk from 34 lb of meal.

The length of the lactation was not significantly affected by the treatment.

In the second experiment, three groups of four cows on a 9-week change-over trial (4 May-5 July) grazed herbage containing an average of only 17·6% dry matter and 3·8% crude fibre. On the three treatments the cows ate pasture only, pasture plus 1·6 lb hay/day and pasture plus 5·7 lb of meal/day. The meal consisted of four parts by weight of undecorticated cotton cake, four of bruised oats and three of locust beans.

Milk yield was significantly increased from 41·8 lb on the all-grass ration to 43·2 lb/day on the meal treatment but the hay did not affect milk yield.

The fat content of the milk was significantly increased from 3·77 to 3·91% on the hay treatment, whereas the solids-not-fat content of the milk was not significantly affected by any of the treatments.

At the present-day prices of the feeds and with cows on good leafy pasture it was clearly uneconomic to feed the meal supplements.
The effect of the plane of energy nutrition of the cow during the late winter-feeding period on the changes in the solids-not-fat content of milk during the spring-grazing period
Authors: Rook J. A. F. , Line C. , Rowland S. J.
Published: June 2009

Three groups of eight Friesian cows, four of high and four of low milk yield, were given during the last month of the winter-feeding period rations that provided respectively low, normal and high planes of energy nutrition, at approximately 75,100 and 130% of the Woodman standards for starch equivalent (S.E.). They were then all changed to the grazing of good, spring pasture, without supplementary food. The changes with grazing in solids-not-fat (S.N.F.) content and yield of milk were markedly influenced by the previous level of winter feeding. After 15–18 days of grazing the mean changes in S.N.F. percentage were +0·33, +0·11 and –0·12 for the low, normal and high energy groups, and the corresponding changes in milk yield were +7·70, +2·13 and –0·68 lb per cow per day. The changes in S.N.F. reflected mainly changes in protein content, and to these casein, β-lacto-globulin and α-lactalbumin all contributed. Small, differential changes were found in the fat and lactose contents of the milk. The effects of the level of initial milk yield of the cow on the various responses to grazing are recorded.

These observations support the view that when a rise in S.N.F. with spring grazing occurs it probably results from an improvement in the plane of energy nutrition. There appears to be no need to postulate a special effect of any specific herbage constituent.
Tallowy discoloration and trace metals in cheddar cheese
Authors: Bishop F.
Published: June 2009

The characteristics are given of a Chaddar cheese defect known as ‘tallowy discoloration’ or ‘white streak’. In the tallowy portions of the cheese the copper content is lower and the iron content higher than in the adjacent normal cheese. The copper probably migrates in cheese following oxidation of the sulphydryl compounds in the tallowy area while the unexpected distribution of iron may be explained by changes that occur during salting of the curd. The proportion of ferrous to ferric iron tends to increase as the cheese matures and tallowy portions of cheese do not contain less ferrous iron than adjacent portions.

The addition of iron salts to cheese milk did not increase the incidence of tallowy discoloration, but the addition of sufficient copper salts reduced it. Although the sulphydryl content of cheese appeared to be related to tallowy discoloration, little evidence of the part it plays was obtained. The oxidation of sulphydryl groups and the formation of peroxides occurred more readily at lower temperatures.

The significance is discussed of ferrous iron in a fat-oxidizing system where copper does not increase oxidation.
Physical properties of milk fat: II. Some factors influencing crystallization
Authors: de Man J. M.
Published: June 2009

The crystal habit of milk fat is determined by the cooling procedure employed and is changed markedly by interesterification (randomization) of the fat. X-ray diffraction analysis indicated that slowly cooled milk fat occurs in both beta prime and beta modifications, whereas in rapidly cooled milk fat, evidence for the beta prime modification only was obtained. The long spacing was greatly increased by interesterification, especially when the fat was slowly cooled. The presence or absence of certain high melting glyceride fractions greatly influenced solid fat content, softening point and hardness of milk fat.
Fat oxidation in Cheddar cheese
Authors: Riddet W. , Whitehead H. R. , Robertson P. S. , Harkness W. L.
Published: June 2009

Fat and carotene oxidation in Cheddar cheese may give rise to bleached areas surrounding slits in the cheese and to a tallowy flavour. It was shown that direct contact of the fat with atmospheric oxygen was essential for oxidation to occur, and examination of cheeses showed that slits running from the rind into the interior provided this contact. Factors enhancing slit formation such as gas production by bacteria and mechanical shock to the cheese were shown to increase the incidence of tallowy discoloration. Factors which tended to exclude oxygen such as waxing the cheese surface, wrapping the cheese in plastic film or sealing in a tin were shown to reduce the incidence of the fault or eliminate it.

Accelerating factors were shown to be low cheese storage temperature, excess moisture in the cheese and possibly low salt content. Various factors which may be relevant to a commercial cure for discoloration are also discussed.
A comparison of the influence of Streptococcus lactis and Str. cremoris starters on the flavour of Cheddar cheese
Authors: Perry K. D.
Published: June 2009

Comparable cheeses were made using single strains of Streptococcus cremoris and Str. lactis as starters. The three Str. lactis strains imparted a characteristic rather abnormal flavour to the cheese, whereas the three strains of Str. cremoris all gave cheeses of normal flavour. The abnormal flavour caused by the lactis cultures increased in intensity as ripening proceeded, and differed slightly from strain to strain.

Bacteriophage usually developed slightly in the whey and in the curd during the manufacturing process, but never to such a degree as to delay acid production unduly. The extent of phage development did not have a significant influence on cheese flavour.

All the lactis strains survived in much larger numbers in the cheese than the cremoris strains. The simplest explanation of the data is that the ‘lactis’ flavour was a direct effect, due to flavour substances produced by the Str. lactis cells present in the young cheese.
Enhancement of the flavour of Cheddar cheese by adding a strain of micrococcus to the milk
Authors: Robertson P. S. , Perry K. D.
Published: June 2009

Three strains of micrococci and two of pediococci were individually tested for effect on Cheddar cheese flavour by their addition to cheese milk. Only one of the micrococcal strains had a significant effect on flavour. In twenty-eight of the thirty-three trials with this strain the flavour of the experimental cheeses was appreciably better than that of the corresponding control cheeses; in the other five trials the experimental and control cheeses were similar in flavour.

This micrococcus did not grow appreciably during manufacture or ripening of the cheese, the peak number being present in the curd at the time of pressing. The count fell to less than 30% of the peak number after 1 week, and to less than 0·5% after 5 weeks.

The ways in which the micrococcus may have influenced the flavour of the cheese are discussed and attention is drawn to the possibility that bacterial action in the milk and the young cheese may play an important part in flavour development.
The effect on the performance of growing pigs of the level of meal fed in conjunction with an unrestricted supply of whey
Authors: Mitchell K. G. , Sedgwick P. H.
Published: June 2009

Results are reported of an experiment made under commercial conditions on the effect of the level of meal fed in conjunction with an unrestricted supply of whey on the performance and carcass quality of pigs.

All the pigs received the same meal mixture and had continuous access to an unrestricted supply of whey. The four treatments were: (1) 3 lb meal per pig per day reduced to 2 lb at 13 weeks of age; (2) 3 lb meal per pig per day throughout; (3) 2½ lb meal per pig per day throughout; and (4) as (1) but the daily allowance of meal increased to 2½ lb/pig at 20 weeks of age. There were five pens of nine group-fed pigs on each treatment, involving a total of 180 pigs. The pigs were on experiment from 8–9 weeks of age to bacon weight. Comprehensive carcass measurements were made on all the pigs.

Mean differences in rate of growth, efficiency of food utilization and carcass quality between the four groups of pigs were small and were not statistically significant. The significant differences in the proportions of meal and of whey consumed by the pigs on the different treatments during the growing period are discussed in relation to relative prices of the two foods. It is concluded that where unrestricted whey feeding is to be used, the feeding system employed in treatment 3 could be recommended in most of the environmental and economic situations likely to be encountered in practice.

The superior performance of the pigs in the experiment compared with that in earlier trials is discussed in relation to the stock improvement work and concurrent improvements in housing and management carried out during the intervening years on the Cow and Gate farm in Dorset where the experiments were conducted.
The incidence of bacteria in cheese milk and Cheddar cheese and their association with flavour
Authors: Franklin J. G. , Sharpe M. Elisabeth
Published: June 2009

The numbers and types of non-starter lactic acid bacteria, lipolytic bacteria and group D streptococci in cheese milks and corresponding Cheddar cheeses have been studied and their relationship to cheese flavour discussed. Different milks, heat-treatments and starters were used, and their association with flavour investigated. The pH and fat, salt and moisture contents of the cheeses were also determined.

The non-starter lactic acid flora consisted mainly of Lactobacillus casei, L. plantarum, L. brevis, L. buchnerii, Pediococcus spp. and Leuconostoc spp. Lactobacillus casei was nearly always present in the milks and cheeses, predominating in most of the cheeses, particularly in those made from milk which received the most severe of the three heat-treatments tested (160°F for 17 sec). Leuconostocs were not found in any of the cheeses. Other species sometimes occurred in approximately equal numbers to L. casei, particularly in cheeses manufactured from the milder heattreated milks. Cheeses made from milk receiving the highest heat-treatment contained fewest bacteria and scored lowest for flavour. The average flavour scores increased as the number of species contributing to the non-starter lactic acid flora at the time of tasting increased.

The lipolytic organisms capable of hydrolysing butterfat consisted mainly of Gram-positive cocci, predominantly Staphylococcus saprophyticus. The group D streptococci occurred infrequently, Streptococcus faecium being the most commonly occurring species.

A definite correlation was found to exist between the starters used and the flavour of the cheeses. The pH of the cheeses was associated with the flavour, but the fat, moisture and salt contents of the cheeses showed no definite effect.
Hydrogen sulphide in Cheddar cheese; its estimation and possible contribution to flavour
Authors: Lawrence R. C.
Published: June 2009

A modified entrainment method is described for the estimation of microquantities of hydrogen sulphide in cheese. Optimum recovery is only possible if the conditions are very acid, if oxygen is excluded and if appreciable loss by diffusion is avoided by minimizing the surface area of the sample and the time it is exposed to the atmosphere. The reproducibility of determinations from the same cheese was satisfactory.

The concentration of H2S in New Zealand Cheddar cheese curd at hooping was less than 20 μg/100 g but increased after ripening for 1–4 months to an average concentration of 55 μg, thereafter remaining fairly constant. There appeared to be no simple relationship between characteristic Cheddar flavour and H2S concentration.
Destruction ofBacillus subtilisspores with solutions of sodium hydroxide
Authors: Whitehouse R. L. , Clegg L. F. L.
Published: June 2009

The rate of destruction ofBacillus subtilisspores by sodium hydroxide solutions in the range of atmospheric temperatures 34—82 °F was studied: (a) to provide information which might be used in practice for immersion cleaning of dairy utensils in sodium hydroxide solutions at low atmospheric temperatures, and (b) to examine the nature of the disinfection curves by slowing down the rate of disinfection. The results expressed as a three-dimensional graph showed that an increase in temperature from 34 to 82 °F had a more marked effect on spore destruction than an increase in concentration of sodium hydroxide from 1·5 to 5·0%. The overall effect could be expressed as

wheret= time in hours for the 99% destruction ofB. subtilisspores,C= concentration of NaOH (%, w/v) and θ = temperature, °F. Since the time for the 99% destruction ofB. subtilisspores by a 2% NaOH solution at 34 °F is 5 times that of a 5% solution, immersion cleaning in cold climates might be assisted by increasing the concentration of NaOH from the normal 2–3 to 5%. Results in disinfection tests at low temperatures were more variable than had been observed in previous work at higher temperatures. These surprising results prevented a careful study of the nature of the disinfection curves and confirmed previous conclusions that such curves are basically sigmoid.
The effect of concentrates on the rate of disappearance of digesta from the alimentary tract of cows given hay
Authors: Campling R. C.
Published: June 2009

Two experiments were conducted with non-lactating cows to examine the effect of adding concentrates to a diet of hay on the rate of disappearance of digesta from the alimentary tract. The addition of large amounts of concentrates to the diet of cows offered hay ad lib. decreased the voluntary intake of hay, increased slightly the digestibility of the organic matter and decreased markedly the digestibility of the crude fibre of the diet. Also, the addition of concentrates increased the mean time of retention of stained hay residues in the alimentary tract and increased the time/kg hay the cows spent ruminating. At the end of a meal the amount of digesta in the reticulo-rumen of the cows offered hay ad lib. with restricted amounts of concentrates was about the same as that found when offered hay ad lib. as the only food. The results are discussed in relation to the regulation of the voluntary intake of hay by the cow.
The stability of milk protein to heat: III. Objective measurement of heat stability of milk
Authors: White J. C. D. , Davies D. T.
Published: June 2009

An objective test has been developed to help in assessing the value, as a method for determining the heat stability of milk, of the subjective test described by Davies & White (1966a). The objective test showed that coagulation time, as determined by the subjective test, is a reasonably accurate measure of the induction period that precedes the onset of initial rapid coagulation, but that coagulation proceeds in 2 different ways depending primarily on whether the coagulation of the milk is good (initial clots large) or poor (initial clots small). The latter finding confirms the view that in studying heat stability these 2 categories of milk should be examined separately.
Pediococci in Cheddar cheese
Authors: Fryer T. F. , Sharpe M. Elisabeth
Published: June 2009

Fifty-nine strains of pediococci were isolated as representing the predominant non-starter flora in a series of Cheddar cheeses made over a period of 5 months. All strains had the same physiological characteristics and were identified asPediococcus cerevisiae. A common antigen was found in 54 of the strains, whereas in the other 5 the antigenic component appeared to be related but not the same. Both antigens were located in the cell wall.

All the strains required folinic acid for growth and it was shown with one strain that the small amount of growth which occurred in sterile milk was greatly increased by the presence of the folinic acid producing starterStreptococcus cremoris924.
Factors affecting the design of milk total solids testing schemes
Authors: O'Keeffe M. G.
Published: June 2009

An analysis of variance was applied to the ‘within herd’ variance of milk total solids in order to find the contribution due to sampling, testing and biological variances on a balanced 8 × 8 two factor (herds and days) experiment with replicate sampling and testing. Testing samples from every consignment from 10 herds over a 12-month period showed that the mean monthy ‘within herd’ variance was 0·039 and the yearly ‘within herd’ variance was 0·085. A formula is given showing how the variance of the mean for compositional quality testing can be obtained and on which the design of testing schemes can be based.
Thermorésistance des spores declostridium tyrobutyricumetClostridium butyricum
Authors: Cerf O. , Bergere J.-L. , Hermier J.
Published: June 2009

Clean spores suspensions of 3 strains ofClostridium tyrobutyricumwere prepared after culture in dialysis sacs. The survivor curves of the spores heated at 90 °C in 0·033 M phosphate buffer (pH 7·0) or in skim-milk were logarithmic. From the thermal-death-time curves the following values were calculated:Dat 121 °C = 0·003−0·012 min andz= 8·4−10 °C when spores were heated in phosphate buffer;Dat 121 °C = 0·006−0·008 andz= 9·5−9·9 °C when spores were heated in milk.

When clean spores of 2 strains ofClostridium butyricumwere heated at 85 °C in 0·005 M phosphate buffer (pH 7·0) the survivor curves were logarithmic, but ‘tails’ were observed after heating in skim-milk. The value ofDat 85 °C was lower than that obtained with spores ofC. tyrobutyricum.
The influence of the dissolved oxygen in milk on the stability of some vitamins towards heating and during subsequent exposure to sunlight
Authors: Ford J. E.
Published: June 2009

Heat sterilization of milk destroyed about 50% of its folic acid activity, and subsequent exposure of the milk to sunlight caused a progressive further loss. This loss of folate, as of vitamin B12, was a consequence of the oxidative destruction of the milk's ascorbic acid, and was largely prevented by thorough exclusion of oxygen from the milk during heat processing and subsequent storage. With thiamine, riboflavin, nicotinic acid, vitamin B6and biotin, stability towards heating and during exposure to sunlight was affected little, if at all, by the oxygen tension in the milk.
The influence of the milk ejection reflex on the flow rate during the milking of ewes
Authors: Labussière J. , Martinet J. , Denamur R.
Published: June 2009

In order to obtain more information on the importance of the milk ejection reflex in the lactation of normal ewes, experiments were conducted to determine whether the neuroendocrine reflex is able to modify the parameters which characterize the flow rate of the milk under normal milking conditions.

Ewes were allowed to suckle their lambs freely during the 3 days following parturition. They were then milked with a machine and the individual milk production was measured volumetrically at each milking. Different fractions obtained during milking (‘machine milk’, ‘machine strippings’ and ‘hand strippings’), and the milk flow, were measured using a sensitive recording system. In further experiments, machine milking was performed after intravenous administration of oxytocin, during general anaesthesia, and after unilateral or bilateral denervation of the mammary gland.

The ewes fell into 2 categories: those giving most of their milk in 1 rapid emission, and those giving it in 2 quite separate emissions. The results indicated that the second emission found in some of the ewes was the milk emptied from the acini by the neuroendocrine ejection reflex. Disappearance of the second emission resulted from the administration of oxytocin before milking—which induces passage of the milk from the acini into the mammary cistern—and also from general anaesthesia or denervation of the mammary gland.
The flavour of milk protein
Authors: Ramshaw E. H. , Dunstone E. A.
Published: June 2009

The flavour stability of casein and co-precipitated milk proteins has been examined organoleptically. Differences in flavour stability were correlated with processing conditions and the early stages of the non-enzymic browning reaction were implicated in the off-flavour development. The ‘gluey’ flavour present in stored casein could be removed and the flavour stability improved by treatment with activated carbon or Sephadex. However, a better solution to the problem was to avoid the development of off-flavour by careful choice of conditions of preparation, drying and storage to minimize heat damage and browning. Conditions were established under which milk protein could be expected to have flavour stability during at least 6 months storage at ambient conditions.
Volatile compounds associated with the off-flavour in stored casein
Authors: Ramshaw E. H. , Dunstone E. A.
Published: June 2009

Compounds associated with the ‘gluey’ off-flavour in stored casein have been isolated and identified by a combination of gas chromatography and mass spectrometry. Most of the flavour was found in the non-acid steam-volatile fraction which contained many compounds including n-alkanals, n-alkan-2-ones, furfural and other furan derivatives, benzaldehyde, dimethyl disulphide and benzthiazole. No single compound had the typical gluey flavour, which must be a complex sensation in which the quantities of minor components may determine the specific gluey character. o-Aminoacetophenone was present in the casein in subthreshold amounts. This compound has some gluey flavour and may have a synergistic effect in enhancing the total flavour.
A fractionation of the αs-casein complex of bovine milk
Authors: Annan W. D. , Manson W.
Published: June 2009

The nature of the αs-casein complex of bovine milk has been investigated by cation-exchange chromatography on columns of sulphoethyl Sephadex C-50 of purified preparations of αs-casein and of whole acid-precipitated casein. Three main fractions were separated from each. Two behaved as single homogeneous proteins as judged by starch-gel electrophoresis; they were the main constituent of the complex, αs1-casein, and a closely related phosphoprotein, designated αs0-casein, which was present in small amounts only. The third fraction also constituted only a small part of the total complex. It was heterogeneous on starch gel electrophoresis and contained 2 major and 2 minor components. This fraction, while similar to other members of the αs-casein complex and to β-caseins hitherto described in that it contained phosphorus, nevertheless differed significantly from these since 3 at least of its components contained sulphur either in the form of disulphide bonds or of sulphydryl groupings.

Information is presented on the composition of the 3 fractions including C-terminal end group analysis.
The rennet hysteresis of heated milk
Authors: Morrissey P. A.
Published: June 2009

The phenomenon of rennet hysteresis in heated milk is essentially due to reversible heat-induced changes of calcium phosphate equilibrium which affect the second or calcium ion stage of the rennet coagulation. The phenomenon is shown not only by heated milk but also by all heated caseinate systems provided they contain sufficient calcium to permit of coagulation with rennet and enough phosphate to ensure some degree of colloidal phosphate precipitation during the heating process; its occurrence does not require the presence of micellar casein or of β-lactoglobulin, or the initial presence of colloidal phosphate. Nevertheless, rennet hysteresis is greatly increased in these heated systems if β-lactoglobulin is present owing to the formation of a calcium caseinate/β-lactoglobulin complex which in its renneted condition is much less sensitive to calcium ions than is calcium para-caseinate. The resulting relative prolongation of the second stage of the rennet coagulation renders this phenomenon more apparent by increasing the proportion of the total time occupied by the hysteresis effect.
Synthetic peptide and ester substrates for rennin
Authors: Hill R. D.
Published: June 2009

Rennin hydrolysed the phe-met bond in the peptide H-ser-leu-phe-met-ala-OMe (i.e. methyl ester), the amino acid sequence of which is similar to that around the phe-met bond attacked by rennin in κ-casein. Rennin did not attack other peptides from this sequence not containing serine, and it is suggested that, in both κ-casein and the pentapeptide, the enzymic attack is accelerated by the nearby serine side chain. Rennin also hydrolysed sulphite esters such as phenyl sulphite ester and some N-substituted imidazole compounds such as benzoyl imidazole. Phenyl sulphite esters may be suitable substrate for assaying the activity of preparations of rennin.
Association of lipases with micellar and soluble casein complexes
Authors: Downey W. K. , Murphy R. F.
Published: June 2009

The association of lipase with casein micelles and soluble casein complexes was investigated by gel-filtration on Sephadex G-200 and Sepharose 2B columns which were equilibrated with synthetic milk serum. Gel-filtration indicated that the molecular weight of casein micelles in milk is > 108whereas the casein in colloidal phosphate-free milk is present as soluble complexes of molecular weightca.2×106containing αs-, β- and κ-casein. The soluble complexes appear to be stabilized in the micelle by colloidal calcium phosphate linkages. On addition of pancreatic lipase to milk, activity was impaired due to binding of the enzyme both to micellar and to soluble casein complexes. The enzyme dissociated from the latter during gel-filtration on Sepharose 2B columns. The binding of lipase to casein was not dependent on the presence of colloidal phosphate and consequently complete micellar structure is not essential for association of lipase with casein. Binding of the lipase to phosvitin did not result in a loss of enzyme activity. Lipases in milk appear to be involved in the equilibrium between micellar and soluble casein. The activity of lipases in milk is apparently influenced by this equilibrium. Some problems encountered in the use of gel-filtration to study the interactions of lipases with caseins are described.