bluuebunny/crossref_metadata_2025 huggingface dataset:
The size of lambs at birth—a study involving egg transfer
Authors: Dickinson A. G. , Hancock J. L. , Hovell G. J. R. , Taylor C. S. , Wiener G.
Published: September 2010

The influence of maternal and genetic factors on the size of lambs at birth and on their gestation length has been studied from the results of two experiments involving the transfer of fertilised eggs from one breed of sheep to another. In the first experiment, eggs were transferred reciprocally between old ewes of the large Lincoln breed and of the small Welsh Mountain breed. Results are based on 20 transfer lambs and 14 normally born singles. In the second experiment, 35 pure Lincoln and 28 pure Welsh lambs were born as a result of transferring eggs into 18-month-old nulliparous Scottish Blackface sheep.

The breed type of the lamb was found to be the most important factor influencing weight and cannon length at birth, although maternal-foetal interactions were present. As the maternal environment became poorer, genotypic differences remained distinct but decreased in magnitude. The maternal environment provided by 4th parity Lincoln ewes, if judged by lamb's size at birth, was better than that provided by 4th parity Welsh ewes, and this in turn was better than that provided by 1st parity Blackfaces. Lincoln and Welsh lambs in the same maternal environment differed in average birth weight by 5·7, 3·8 and 3·0 1b. respectively in the Lincoln, Welsh and 1st parity Blackface maternal environments. Lincoln and Welsh lambs, each in their own normal maternal environment, differed by 6·5 lb. The maternal influence on cannon length was similar but small. Gestation length of Lincoln lambs in Welsh recipients was almost 4 days shorter than that of Welsh lambs in Lincoln recipients. In the Blackface maternal environment, Lincoln and Welsh lambs differed little in gestation length but males were, on average, carried about a day longer than were females.

At the individual level, weight of (Blackface) recipient ewe had a somewhat greater effect on lamb's size than had weight of (Lincoln or Welsh) donor ewe. The magnitudes of these ‘genetic’ and ‘maternal’ effects were comparable with those found at the level of group means; even so, donor's and recipient's weight together accounted for only a small part of the individual variation in lamb's size about the group means.

It was concluded that a ewe was able to respond to progressively greater demands made by a lamb or lambs of progressively larger (combined) potential size—but in accordance with the law of diminishing returns—and that the upper limit of maternal accommodation must be considerable. By contrast, the upper limit of mean genetic size at birth appears to be not far above the mean size of single lambs born to their natural mothers in good condition. A model has been constructed from which mean birth weight of lambs can be predicted.
Haemoglobin N of sheep. Age, breed and seasonal distribution
Authors: Efremov G. , Brænd M.
Published: September 2010

The occurrence of Hb N in sheep has been investigated by means of starch gel electrophoresis.

In lambs, Hb N occurred in higher relative amounts than in adults, but not until 9 days of age. One-month-old lambs often showed an Hb N content as high as 10–30%.

Haemoglobin N was observed most in sheep of phenotype AA, less in those of type AB and was found to be absent in BB animals. It was also provoked experimentally by bleedings in sheep of types AA and AB but not in those of type BB.

Comparisons between breeds showed differences in the expression of Hb N. It occurred most regularly in Old Norwegian sheep (Spæl), but usually in concentrations of less than 1%. Hb N was, however, also found in other Norwegian breeds, in Cheviots and in Spanish sheep but not in sheep of the Oxford Down breed.

In two flocks of Spæl and Dala sheep where frequent bleedings were made, Hb N was observed at all times of the year.
A comparison of two indoor farrowing systems for sows
Authors: Robertson J. B. , Laird R. , Hall J. K. S. , Forsyth R. J. , Thomson J. M. , Walker-Love J.
Published: September 2010

1. Over a 3-year period 150 farrowings of Large White sows were used to compare a stall farrowing system with a conventional-pen farrowing system.

2. Farrowing in the stall system of management resulted in a significantly lower percentage mortality both at 3 weeks (5·73±2·70%) and at 8 weeks (7·92±2·89%), than in the conventional-pen system.

3. Both total litter and individual pig weights were higher at 3 and 8 weeks in the stall system.

4. Despite higher building and electricity costs the stall system showed a margin of £1, 14s. per litter over the conventional-pen system.
The correlation between first lactation milk production and longevity in dairy cattle
Authors: Robertson Alan , Barker J. S. F.
Published: September 2010

1. An analysis has been made of the relationship between first lactation progeny test for milk yield and the survival of a bull's daughters to different ages using data for British Friesian, Ayrshire and Holstein-Friesian cows. It was found that the relative effect on survival of differences between bulls in milk yield increased by about 10% per 100 gallons for each lactation survived, e.g. for two bulls differing in heifer progeny test by 100 gallons, that with the higher figure will have 10% more daughters surviving to have a second lactation, 20% more having a third and so on. The probable effect on total length of life is 1·2 lactations per 100 gallons.

2. No evidence was found that selection on first lactation progeny test would reduce productive life in the dairy herd or even that it would increase the proportion culled for reasons other than yield in later lactations.

3. The genetic effects of culling in the first lactation on yield were in agreement with those expected from multiplying the phenotypic selection differential by the heritability. On the other hand, the selection differential in heifer yield produced by culling in later life considerably under-estimated its genetic effect. The effect of culling was to increase the genetic potential of animals for yield in the first lactation by roughly 10 gallons for each lactation survived, so that the average genetic superiority over their heifer contemporaries of cows in the herd at any time would be 30 gallons.

4. The heritability of survival to different ages was significantly different from zero in all analyses. The theoretical prediction that this would have a maximum at the fourth lactation was borne out in one sample but not in the other.

5. The genetic correlation of first lactation yield with survival was lowest in all samples for survival to have a second lactation. For survival to the third or later lactations it was higher than 0·7 in all analyses. As the genetic correlation between first and later yields in these data averaged about 0·8, this can only mean that milk yield is by far the most important genetic determinant of survival at all ages.
The usefulness of muscle fibre diameter in studies of the lean meat content of pigs
Authors: Livingston D. M. S. , Blair R. , English P. R.
Published: September 2010

Samples of the longissimus dorsi muscle were removed by biopsy from 4 pigs at intervals during the period from weaning to 125 lb. live-weight. In parallel studies involving 127 pigs attempts were made to relate mean fibre diameter to indexes of lean meat content of a range of bacon pig carcasses but only poor correlations were obtained. It was concluded that fundamental knowledge of the structure of the longissimus dorsi is not yet sufficiently advanced to allow accurate predictions of this type to be made.
Studies on the nutrition of ruminants. I. Substitution of maize by milled barley straw in a beef fattening diet and its effect on performance and carcass quality
Authors: Lamming G. E. , Swan H. , Clarke R. T.
Published: September 2010

Sixty-four yearling Friesian steers, in eight groups with eight animals per treatment, were fed on pelleted diets containing ground barley straw, maize and soya bean meal. The percentage of straw in the diets varied from 0% to 50% and the crude protein was adjusted in all diets to 12% on an air dried basis. Levels of 0, 10, 20 and 30% ground straw were tested in 1963–4 and 20, 30, 40 and 50% in 1964–5.

Growth rates in the range of 8·28–9·49 kg. per week were obtained, with growth rate falling significantly (P<0·05) by 0·36±0·15 kg. per week for each 10% increase in straw in the 1964–5 trial; the differences between treatments in the 1963–4 trial were non-significant. The efficiency of food conversion varied from 6·5:1 for 0% straw to 7·7:1 for 50% ground barley straw. Feed intake increased as the percentage of straw in the diet rose above 20%. Regressions relating those carcass measurements in which differences between groups were significant to the percentage of straw in the diet were not significant except that for eye muscle area (P<0·05). Neither carcass nor meat quality differed significantly in animals given 20 % and 50 % ground straw.

The results of digestibility trials with male hoggets showed a linear depression in the digestibility of diets as the percentage of straw increased.

The results are discussed in relation to previous knowledge of the factors affecting the voluntary feed intake of ruminants.

Agricultural Research Council, 1965. Recommended procedures used in the measurement of beef cattle and carcasses. H.M.S.O., London.
Observations on the food conversion rate of Specific-Pathogen-Free boars
Authors: Jollans J. L.
Published: September 2010

Data are presented concerning the efficiency of growth of Specific-Pathogen-Free Large White boars on individual performance test. Various aspects of growth rate, backfat thickness and food conversion are compared.

It is suggested that tests should be shortened by starting later, rather than finishing earlier.

Some support is given to the theory that one type of pig may not be suitable, from the point of view of efficiency of growth, for supplying the full range of carcass weights in current demand.
A note on the effect of protein concentration in the diets of pregnant sows on the performance and carcass quality of their progeny
Authors: Livingstone R. M. , MacPherson R. M. , Elsley F. W. H. , Lucas I. A. M. , Lodge G. A.
Published: September 2010

Livingston (1962) showed that high levels of dietary protein during pregnancy increased the mean thickness of muscle fibres of M. longissimus dorsi and M. psoas majoris in newly-born piglets. Livingston did not detect this effect in pigs killed at pork weight. Preliminary results of Elsley and MacPherson (1964) indicated that the concentration of dietary protein during pregnancy can influence the nitrogen content of newly-born pigs when birth weight is standardised to 1 kg. to reduce variation; subsequent results (Elsley, MacPherson and McDonald, unpublished data) did not confirm these findings. Any differences attributable to the nutrition of the pregnant sow which are present in the newly-born pig are of practical importance only if they are reflected in changes in subsequent performance.
Lipid mobilization in pigs selected for leanness or fatness
Authors: Standal N. , Vold E. , Trygstad O. , Foss Irene
Published: September 2010

Lipid mobilization was investigated in pigs selected for high and low backfat thickness for four generations. Both epinephrine and pituitary lipid mobilizing factors (LMF) induced in vitro lipolysis in pig fat. The release of non-esterified fatty acids (NEFA) from fat pads sampled from the group selected for thin backfat, the control group, and the group selected for thick backfat differed significantly, the means being 1·16 ± 0·18, 0·83 ± 0·06 and 0·40 ± 0·04 μmol/100 mg per 3 hr respectively.

The inhibition by pig serum from the same groups of an LMF- induced adipokinesis in rabbits also differed significantly. The mean NEFA concentrations were, in the same sequence, 5·05 ± 0·15, 3·35 ± 0·27 and 1·29 ± 0·11 milliequiv/litre respectively. A difference in feeding level of about 20% between 25 and 90 kg live weight did not influence lipid mobilization in vitro.

The serum inhibition method may be a useful aid to early selection for leanness, since it appears that the method may be used for pigs 5 to 6 weeks old.
The nutrition of artificially reared lambs. 3. The effect of sex on the performance and carcass composition of lambs subjected to different nutritional treatments
Authors: Morgan J. A. , Owen J. B.
Published: September 2010

Forty-eight Suffolk cross lambs were reared artificially from 2 days of age. Sixteen entire males, 16 castrates (castrated by rubber ring at 2 days) and 16 female lambs were allocated at random to a set of 2×2×2 factorial treatments in which feeding was ad libitum or restricted for each of three growth periods—from 2 days old to 15 kg, from 15 to 25 kg and from 25 to 40 kg live weight.

The results showed no apparent interaction of sex and feeding treatment and differences due to sex were apparent only in the period after 25 kg live weight. Entire males grew faster and were more efficient at this stage although there was little difference in voluntary feed intake. Carcasses of the males were lower in fat and energy content and higher in protein content than those of females and castrates.

The feeding treatments in the main had similar effects to those shown in other studies in the series. Restricted milk feeding was compensated for by increased solid food consumption during the milk-feeding stage but in this experiment there was no tendency for restricted lambs to eat more and grow faster when fed ad libitum in the following period. Restricted feeding in the last period, particularly if preceded by restricted feeding, gave higher killing-out percentage, higher fat content and lower protein content in the carcass than feeding ad libitum. This finding was partly explained by the higher weight of the carcasses of the restricted lambs.
Studies on the nutritive value of the diet selected by grazing sheep. VI. The use of tritiated water as a marker to estimate the composition of the diet from material collected by oesophageally fistulated sheep
Authors: Langlands J. P. , Bowles J. E.
Published: September 2010

Five forages were given to three oesophageally-fistulated sheep held in metabolism cages. Estimates of the N, P and K contents of the forages were derived after correcting the composition of the extrusa for salivary contamination by using tritiated water (TOH) as a marker. Estimated N and P contents of the diet were generally higher, and estimated K content was lower, than in the diet. The estimates were variable and could not be used to estimate dietary N, P or K. It is suggested that the ratio of N, P or K to TOH of the pre-feeding saliva sample may have differed from the corresponding ratio during feeding, or that TOH may have moved independently of salivary N, P or K during feeding and processing. These difficulties might be overcome by marking each dietary component with its own isotope.

Estimates of dietary composition were also derived from analyses of squeezed extrusa without correcting for residual saliva or losses in leaching. The error with which dietary N content was estimated was then sufficiently low for most practical purposes. The equation relating dietary and extrusa N contents yielded similar estimates of dietary N to an equation derived in an earlier report.
Selection of dairy bulls on half-sister records
Authors: Owen J. B.
Published: September 2010

A scheme is described for the genetic improvement of milk yield in a large population of dairy cows, based on half-sister selection of young bulls, as an alternative to the normal procedure of progeny testing. The results indicate that the suggested scheme would lead t o an eventual rate of genetic progress very similar to the progeny testing scheme. However, the annual cost of the new scheme is less than a progeny testing scheme, largely because the ‘laying off’ of candidate bulls, to await selection, is completely eliminated. In addition, improvement of the dairy cows shows up sooner in the new scheme; by the 10th year from the start the cumulative genetic improvement is four times greater than for progeny testing.
The water intake of British Friesian cows on rations containing various forages
Authors: Castle M. E. , Thomas Thesca P.
Published: September 2010

The intake of drinking water of lactating British Friesian cows in 14 herds with a total of 840 animals was measured monthly from November to April inclusive. The intake of food, the air temperature and relative humidity were also recorded. The herds which mainly contained autumn-calved cows were managed under controlled commercial conditions.

The average daily intake of drinking water was 49·9 (range 20·1 to 87·1) kg/cow for animals yielding an average of 16·8 kg milk/day in an environment with a mean temperature of 8·2°C and a relative humidity of 84·8%. The amount of water drunk daily was positively and significantly related to the mean daily milk yield and the drymatter content of the ration, but not significantly related to either the mean air temperature or the relative humidity. The average intake of water was 3·70 kg per kg of dry matter consumed after subtracting the amount of water in the milk. On average, 40·0% of the total daily intake of water was drunk between 15·00 and 21·00 hr.

Behaviour studies of 24 hr duration on five herds showed that drinking time ranged from 2·0 to 7·8 min/cow per day, and the rate of drinking varied from 4·5 to 14·9 kg/min.

Recommendations are made for the provision of drinking water for dairy cows being offered a wide range of forages under modern conditions of housing.
Nutritional evaluation of wheat 3. Effects of supplementation with lysine, threonine and methionine of diets based on wheat containing 13% crude protein on the performance of pigs
Authors: Ivan M. , Farrell D. J. , Edey T. N.
Published: September 2010

1. Large White x Landrace pigs were used to study the effects of supplementation with limiting amino acids of diets based on wheat containing 13% crude protein. Measurements were made of growth rate, feed conversion, carcass composition, plasma-free amino acid concentrations, digestibility of dry matter, nitrogen and gross energy, nitrogen retention and metabolizable energy.

2. A wheat diet supplemented with lysine and threonine, the firstand the second-limiting amino acids respectively, produced almost the same growth rate and feed conversion ratio as one supplemented with fish meal and meat meal. Methionine was probably the thirdlimiting amino acid, and additional supplementation with methionine produced a further small improvement in growth rate and feed conversion ratio to the point where they were equal to those on the diet supplemented with fish meal and meat meal.

3. Supplementation of the wheat diet with lysine only produced the same growth rate and feed conversion ratio as a least-cost commercial diet; performance was, however, inferior to that on a wheat diet supplemented with fish meal and meat meal. The commercial diet had a lower dry-matter digestibility.

4. Eye-muscle area of pigs on the wheat diet supplemented with lysine was similar to that of pigs on a wheat diet supplemented with fish meal and meat meal; however, backfat thickness was significantly lower on the latter diet.

5. Except for threonine, plasma-free amino acid concentrations reflected with reasonable accuracy amino acid deficiencies in the diets.
A note on the effect on sow productivity of methallibure administration following a 10-day lactation
Authors: Walker N. , Eddie S. M.
Published: September 2010

Female pigs (sows) which had lactated for about 10 days were allocated at random either to a control group or to a group given 75 mg methallibure per day for 5 consecutive days, followed by an intramuscular injection of 1000 IU PMSG. All sows were mated as soon as they came into oestrus and again 24 hr later. Nineteen out of 21 treated sows exhibited a controlled oestrus 9·4 + 0·25 days after weaning, compared with 21 out of 23 control sows in 8·2 + 0·64 days. Fourteen treated and 17 control sows conceived at that oestrus resulting in total pigs born per litter of 9·4 and 9·9 respectively. None of these differences was statistically significant.
A Note on the use of micronized barley for growing pigs
Authors: Fernandes T. H. , Hutton K. , Smith W. C.
Published: September 2010

An experiment was undertaken to examine the effects of the micronization process followed by grinding on the chemical composition of barley and on digestibility and nitrogen (N) retention in the growing pig. Micronization relative to normal grinding increased the dry matter (DM) content and starch availability in vitro and decreased the protein content of the cereal. Retention of N was not affected by the process but apparent digestibility of the DM, N and gross energy was improved. The improvement in digestible energy content of micronized barley over the ground grain was 3·8%. In a subsequent trial 24 pigs were individually and scale-fed a diet containing 75% of barley in ground or micronized and ground form over the liveweight range 33 to 80 kg. Processing treatment did not influence growth rate, DM food conversion ratio, killing-out percentage, deposition of backfat or area of ‘eye muscle’ in cross-section.
Effect of sampling errors on efficiency of selection indices 1. Use of information from relatives for single trait improvement
Authors: Sales Jill , Hill W. G.
Published: September 2010

An analysis is undertaken of the effect of errors in estimates of parameters, particularly the intra-class correlations, on the response from selection for one trait using an index of individual together with full- and/or half-sib family records. A distinction is drawn between the response (R) possible with use of the optimum index, that predicted (R) and that achieved (R*) with an index which uses the sample estimates of the parameter values.

It is found that the loss of efficiency (R*–R) using sample estimates is very small even for estimates far from the correct value. R is more sensitive to errors, particularly of the heritability and phenotypic variance estimates. Since the latter also appear in the prediction of response from individual selection, errors in predicting the relative responses from index and individual selection are small. Expected values of the proportional loss in response,

are approximately proportional to the variance of the estimate of intra-class correlation. It is shown that in practice initial experiments with 20 or so families may be sufficient to get average proportional losses down to less than 1%.
Intake by and performance of early-weaned calves offered unwilted or wilted silage supplemented with a cereal and protein concentrate or dried grass
Authors: Marsh R.
Published: September 2010

Forty-two British Friesian castrated male calves of 1 to 3 weeks of age were offered ad libitum unwilted or wilted silage made from the same sward for 21 consecutive weeks. Both silages were supplemented with a cereal and protein concentrate at two restricted levels of intake or with dried grass cobs offered ad libitum. There was little difference i n the chemical composition ofthe two silages except for DM content. Dry-matter intake of wilted silage was slightly but not significantly greater than that of unwilted silage. Differences between silages in daily gain or final live weight were not significant.

An increase in the intake of the cereal and protein concentrate led to a significant decrease (P < 0·001) in silage DM intake and a significant increase (P < 0·001) in daily gain andfinallive weight. Calves offered dried grass as a supplement to silage ate similar quantities of silage DM to calves offered an equal amount of the cereal and protein supplement but gained significantly less (P < 0·001) live weight. When intakes were presented on a unit metabolic live-weight basis, calves ate significantly more (P < 0·001) silage when supplemented with dried grass than calves offered the cereal and protein supplement.
Effect of silage additives on the intake and performance of male calves and steers
Authors: McIlmoyle W. A.
Published: September 2010

In two feeding experiments, an untreated silage which had received no additive was compared with silages which had received either formic acid (‘Add-F’) or a formalin and sulphuric acid mixture (‘Sylade’). The ‘Add-F’ was applied at the rate of 3·81/t and ‘Sylade’ at the rate of 3·1 1/t of fresh herbage harvested from a perennial ryegrass and white clover sward.

The silages were offered ad libitum to 30 British Friesian male calves (mean fasted live weight 97 kg) in Experiment 1 and to 27 steers (mean fasted live weight 320 kg) of mixed breed in Experiment 2. Concentrate was offered to the animals in Experiment 1 at the rate of 0·86 kg dry matter/head per day.

In each experiment the intakes of dry matter and digestible organic matter were higher from the additive-treated silages than from untreated silage.

In Experiment 1 the application of ‘Sylade’ increased significantly (P < 0·05) the mean daily unfasted live-weight gain (0·87 kg/day) over that for animals offered untreated silage (0·74 kg/day). In Experiment 2 the mean daily unfasted live-weight gains from ‘Sylade’-treated (0·70 kg/day) and ‘Add-F’-treated silage (0·78 kg/day) were significantly higher (P<0·01) than that from untreated silage (0·38 kg/day).
Effects of restricting the water intake of dairy cows upon their milk yield, body weight and blood composition
Authors: Little W. , Sansom B. F. , Manston R. , Allen W. M.
Published: September 2010

1. Water intake was measured in eight lactating cows. Subsequently n i an experiment of a 4 × 4 Latin square design, each cow received 100, 87, 73 and 60% of its voluntary intake for 6 days followed by an 8-day recovery period.

2. Measurements were made of the intake of feed, milk yield and quality, water, Na and K balances, metabolic profiles, and serum and urine osmolalities. The cows were weighed at the beginning and end ofthe experimental periods, and pulse, respiration and rumination rates and rectal temperatures were measured daily.

3. Milk yield decreased significantly with increasing water deprivation. A 40% reduction in water intake was associated with a 16% decrease in intake of dry matter and a concomitant 16% decrease in milk yield. The only significant change in milk composition was a small increase in lactose concentration with increasing water deprivation.

4. There was no significant reduction in urine output, but the output of water in faeces was reduced and there was evidence of a reduction i n total body water which approximated the reduction in body weight. 5. Concentrations of serum Na and urea-N and serum osmolality increased significantly with increasing water deprivation.
Influence of breed, birth weight and weather on the body temperature of newborn lambs
Authors: Sykes A. R. , Griffiths R. G. , Slee J.
Published: September 2010

The rectal temperature of 208 lambs of Scottish Blackface, Tasmanian Merino, Southdown, Cheviot, Soay and Finnish Landrace breeds was measured between 15 and 25 min after birth, and that of 94 lambs again 1 hr after birth. Relationships within breeds between rectal temperature and birth weight, weather (temperature and wind speed) and gestational age were examined.

Within the range of birth weights and weather encountered over a period of years Scottish Blackface, Cheviot and Soay breeds maintained homeothermy at birth. In contrast, the Merino and Finnish Landrace breeds, which had comparable birth weights to the Black-face and Soay respectively, showed significant reductions in body temperature sometimes exceeding 10°C in cold weather. The Southdowns also showed hypothermia. In the Merinos and Finns, 30 and 54% respectively of the variation in rectal temperature was accounted for by birth weight and weather.

Of those lambs with low rectal temperatures 20 min after birth, few showed any improvement after 1 hr. Merinos in cold weather showed the least tendency to recover.

Possible reasons for the different performance of the breeds and the implications for lamb survival are discussed.
Evaluation of molassed sugar-beet pulp nuts supplemented with urea as an energy and protein source for lactating ewes
Authors: Ducker M. J. , Fraser J. , Hemingway R. G.
Published: September 2010

A molassed sugar-beet product with added urea and dicalcium phosphate was evaluated as an energy and protein source for housed lactating ewes. Comparisons were made with a barley-vegetable protein and a barley-urea concentrate each formulated to supply approximately the same amount of crude protein. The overall performance of ewes and lambs given barley and vegetable protein was very significantly superior to that of ewes receiving the sugar-beet product. At 6 weeks after lambing the ewes given barley and vegetable protein had lost 57% (with singles) and 23% (with twins) less weight and their lambs had grown 28% (singles) and 48% (twins) more quickly than for ewes receiving the sugar-beet product. The intermediate performance of the ewes receiving barley and urea illustrated that the difference between the barley-vegetable protein concentrate and the sugar-beet product was both an energy and a protein effect.
The use of loci associated with quantitative effects in dairy cattle improvement
Authors: Soller M.
Published: September 2010

The use in dairy cattle improvement of loci associated with quantitative effects that might be found by genetic analysis is discussed. These methods can make a significant contribution only if they result in the identification of quantitative loci whose inheritance can be followed in a simple Mendelian manner. Another possibility, the identification of genetic components of production having a higher heritability than overall production, would make only a minor contribution to increased genetic progress. Selection of young males, according to the estimated breeding value associated by linkage with particular marker alleles in their sire, will not make a detectable contribution to genetic improvement.
The effect of urea on digestion and voluntary intake by sheep of diets supplemented with fat
Authors: Ørskov E. R. , Hine R. S. , Grubb D. A.
Published: September 2010

Two experiments were conducted to determine whether the depression in fibre digestion caused by inclusion of fat in diets could be alleviated by addition of urea and whether the physical incorporation of fat in itself caused a reduction in rate of fibre digestion.

Early-weaned lambs were given dried grass containing either 65 or 130 g/kg of tallow with or without 15 g/kg of urea. Fat inclusion caused a linear depression in intake and fibre digestibility. The depression in intake was partly alleviated by urea inclusion, but urea did not affect fibre digestibility.

The physical incorporation of fat into dried grass did not in itself appear to depress rate of digestion. It is suggested that if coating of feed particles is important then this would be due to non-esterified fatty acids in the rumen and not to triglycerides.
Possible association between the breeding value of dairy bulls and milk yield of their mates
Authors: Taylor C. S. , Monteiro L. S. , Murray J. , Osmond T. J.
Published: September 2010

British Friesian and Jersey cows were mated either to high contemporary comparison (CC) bulls for their first pregnancy and to low bulls for their second pregnancy, or vice versa. Sixteen proven bulls were used, four ‘high’ and four ‘low’ in each breed. Least squares analysis of data on 175 lactations gave estimates of each bull's effect on his mates' milk yield in the ensuing lactation, but there were no significant differences between bulls for this ‘mate effect’. The high bulls tended to depress their mates' milk yield in the subsequent lactation and the low bulls tended to increase it. Weighted regressions of the ‘mate effect’ on breeding value had negative slopes for both breeds and for first and second lactations, separately or combined. The high CC bulls appeared to depress their mates' milk yield by at least 10% of the amount by which their daughters' yield was expected to increase.
Age, weight or total feed intake as bases for the performance testing of growing pigs
Authors: Lodge G. A. , Lister D. , Wood J. D. , Wolynetz M. S.
Published: September 2010

In an experiment which showed that the results of a genotype comparison are influenced by the design of the test, 16 castrated male and 16 female pigs of each of Large White (LW) and Gloucester Old Spot (GOS) breeds were allocated equally among four treat- ments: WW—rationed by weight and slaughtered by weight; A A—rationed by age and slaughtered by age; AW—rationed by age and slaughtered by weight; and WF—rationed by weight and slaughtered after a common total feed intake. The experiment was designed so that performance of LW would be similar on all treatments, and the degree to which the GOS differed from the LW on each of these treatments was then evaluated. All pigs started on the experiment at 12 weeks of age, at which time mean weight of the LW was 14% greater than the mean for the GOS. The only between- breed difference that was statistically significant (P<0·05) on all treatments was weight of lean. Average daily gain and efficiency of feed conversion were significantly different between breeds only on the WW treatment. Weight of fat was significantly different on WW and AW but not on AA or WF.
Pre-pubertal mammogenesis in the sheep 1. The effects of level of nutrition on growth and mammary development in female lambs
Authors: Johnsson I. D. , Hart I. C.
Published: September 2010

Female lambs were given a high energy and high protein diet in varying amounts to achieve either high (H; 220 g/day) or low (L; 110 g/day) rates of gain during two consecutive periods between 4 and 20 and 20 and 36 weeks of age. The effects on body growth and mammary gland development were compared by slaughtering an initial group of four lambs at 4 weeks of age (mean live weight 11 kg), eight L lambs (24 kg) and eight H lambs (33 kg) at 20 weeks of age, and eight LL lambs (36 kg), eight LH lambs (49 kg) and eight HL lambs (48 kg) at about 36 weeks of age.

At slaughter, a single mammary fat pad from each lamb was trimmed and weighed, and the deoxyribonucleic acid (DNA) content of the portion containing parenchyma determined. The mean weight (g) and DNA content (mg) were: 4-week-old lambs, 8·6 g, 1·5 mg; L, 14·7 g, 32·3 mg; H, 30·0 g, 25·9 mg; LL, 46·0 g, 61·2 mg; LH, 86·7 g, 91·0 mg; HL, 70·3 g, 73·0 mg respectively. Relative growth coefficients for mammary parenchyma, estimated from the increase in DNA relative to that for live weight, were 3·7 and 2·4 for L and H lambs respectively, between 4 and 20 weeks, and 1·6, 1·4 and 2·6 for LL, LH and HL lambs respectively, between 20 and 36 weeks of age.

These results are consistent with the hypothesis that a high plane of nutrition can decrease the rate of allometric growth of mammary parenchyma before puberty. However, the cessation of this growth phase was not related to the attainment of puberty, or of a specific live weight or age, but may be related to the availability of mammary fat pad tissue limiting further parenchymal development after 20 weeks of age.
Pre-pubertal mammogenesis in the sheep 2. The effects of level of nutrition on the plasma concentrations of growth hormone, insulin and prolactin at various ages in female lambs and their relationship with mammary development
Authors: Johnsson I. D. , Hart I. C. , Simmonds A. D. , Morant S. V.
Published: September 2010

Female crossbred lambs were given a high energy and high protein diet in varying amounts to achieve either high (H; 220 g/day) or low (L; HOg/day) rates of live-weight gain during two consecutive periods between 4 and 20 and 20 and 36 weeks of age. Blood samples were collected via jugular catheters at either 1-h or 2-h intervals over a 28-h period from five lambs on each rearing treatment at 10, 14, 18, 26 and 34 weeks of age for the measurement of prolactin, growth hormone (GH) and insulin. In addition, samples were collected within 2 weeks of slaughter from all eight lambs on each treatment that were slaughtered at either 20 weeks (L and H treatments) or 36 weeks of age (LL, LH and HL treatments) for the assessment of mammary development.

The timing of once-daily feeding influenced the plasma profiles of all three hormones measured, but became less obvious with increasing age. Both mean plasma GH, and the influence of level of nutrition on the mean, declined with increasing age. Mean plasma insulin increased with age but did not differ between rearing treatments until 26 weeks, despite large differences in food intake. Mean plasma prolactin in H lambs increased significantly between 10 and 18 weeks, but a similar response did not occur in L lambs. The greater mammary development of L lambs was associated with increased plasma concentrations of GH and reduced concentrations of prolactin. However, the large variation in total mammary parenchymal deoxyribonucleic acid between individuals within each rearing treatment at 20 or 36 weeks of age was not consistently explained by the variation in any of the hormones measured.
The effect of environmental temperature during pregnancy on thermoregulation in the newborn lamb
Authors: Stott A. W. , Slee J.
Published: September 2010

Twenty-four pregnant Scottish Blackface ewes were divided into three temperature-treatment groups 14 days before expected lambing: closely shorn and kept at 6°C (cold treatment, CD); in full fleece at 26°C (warm treatment, WM); and in full fleece at 6°C (controls, CL). Food allocation and intakes were similar for each group. Their lambs were tested for cold-induced summit metabolic rate capability (SMR) on the day of birth at a mean age of 12 h using water immersion to provide cooling. On the following day, the calorigenic response to subcutaneous injections of noradrenaline (NA) was measured to assess non-shivering thermogenesis capability. The ewes were blood-sampled during pregnancy and the lambs before and after the SMR test.

In the ewes, blood glucose and free fatty acid levels were higher during cold treatment, but not significantly so. Blood glucose was lower in lambs from CD ewes (CD lambs) before SMR tests; other differences were not significant.

During the cold test, SMR was highest in CD lambs, but not significantly so. Rectal temperature declined least during test in the CD lambs (P < 0·05).

The peak metabolic response (PMR) following NA injection was about 1·5 times greater in CD lambs than in the CL and WM lambs (P < 0·05). The mean elevation of PMR over thermoneutral metabolic rate was respectively: 2·8, 1·8 and 1·7 times in the CD, CL and WM lambs (P < 0·05), and this elevation was sustained for longer in the CD lambs (P < 0·01). Thus, the total metabolic response to NA was markedly greater in CD lambs.

It was concluded that cold exposure during late pregnancy favoured the deposition of (or checked the normal decline in) foetal brown adipose tissue, so raising the neonatal capacity for non-shivering thermogenesis.
Interrelationships between growth, gonadotrophin secretion and sexual maturation in gilts reared in different litter sizes
Authors: Deligeorgis S. G. , English P. R. , Lodge G. A. , Foxcroft G. R.
Published: September 2010

One gilt from each of 24 littermate trios was assigned at birth to one of three treatments which were to adjust litter size to six, nine or 12 piglets. Plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured before and after stimulation with 1 ng gonadotrophin-releasing hormone (GnRH) per kg body weight at 55 and 140 days of age. At 150 days, oestrogen was administered and ovarian and uterine responses were measured at slaughter on day 160.

Litter size significantly modified pre-weaning growth rate (P < 0·01) but did not influence gonadotrophin secretion or sexual maturity at slaughter. The family of origin significantly influenced ovarian and uterine development (P < 0·05) and the LH and FSH responses to GnRH at 55 days (P < 0·05). Family size (P < 0·01) and sex ratio of the litter at birth (P < 0·05) also influenced the ovarian response to oestrogen treatment. Significant sire effects on ovarian and uterine development were established (P < 0·05); for the progeny of individual boars significant differences in the response to oestrogen were associated with significant differences in growth rate (P < 0·001).

Variations in family birth and litter weaning weights were negatively correlated with ovarian and uterine development (P < 0·05), whereas all measures of growth from weaning to slaughter were significantly and positively correlated with sexual maturity at slaughter (P < 0·05).

Basal FSH and the responses of both LH and FSH to GnRH at 55 days were correlated with growth rate at day 55 (P < 0·05). Basal LH and FSH at day 140 were correlated with ovarian and uterine development at day 160 (P < 0·05).
Sources of variation in yields and concentrations of milk solids in dairy cows
Authors: Rook A. J. , Fisher W. J. , Sutton J. D.
Published: September 2010

Eighteen multiparous Holstein-Friesian cows were offered grass silage ad libitum and 3,6 or 9 kg dry matter per day of concentrates. Triplicate milk samples were taken at each of two daily milkings over a 28-day period and analysed for fat protein and lactose concentration. Milk yield and fat concentration were more variable than protein and lactose concentrations both between animals and between days. Sampling variation was small for all component concentrations. The main source of variation for all traits was time of milking (morning or afternoon) followed by variation between cows and by day-to-day variation. There was little linear trend with time in the data due to cows being close to peak yield. There was no evidence of cyclical variation over time for any trait. Mean weekly or monthly yields and concentrations were better predicted using samples from four rather than from two consecutive milkings but there was no further advantage from using six samples.
The performance of crossbred dairy calves given different levels of whole milk and weaned at different ages
Authors: Khalili H. , Crosse S. , Varvikko T.
Published: September 2010

Forty-five Friesian × zebu crossbred calves (4 days old) were used to evaluate the effect of feeding different levels of whole milk and weaning at different ages. A total of 252 I whole milk offered over 12 weeks was compared with a feeding level of 134 I milk offered over 8 weeks. Water given ad libitum was also compared with allowing access to water once daily. The calves were penned and fed individually. The average daily gain of the calves weaned at 12 weeks was 464 g compared with 378 g for the calves weaned at 8 weeks of age and allowed access to water once daily and 422 g for the calves weaned at 8 weeks and given water a d libitum. Feeding extra milk and weaning at 12 weeks decreased the intake of concentrates and significantly (P < 0·05) increased live-weight gain. Allowing ad libitum access to water was associated with an increase in concentrate intake but this was not reflected in a significant increase in animal performance.
Lactation curves for several US sheep breeds
Authors: Sakul H. , Boylan W. J.
Published: September 2010

Lactation curves for several dairy traits in sheep were studied. Data were collected from seven pure breeds, three synthetic breeds and twelve single breed crosses in a 5-year milking trial. Wood's lactation model (yn = anbe-cn) was used to describe the lactation curves. Actual and fitted lactation curves had the same shape within each trait except for proportion of lactose. Correlations between actual and fitted lactation curves ranged from 0·92 to 0·99 for all traits except lactose (0·24). There was no apparent explanation for the low correlation for lactose content. It was concluded that the algebraic formula can be used to obtain estimates of parameters for sheep lactation curves. However, some caution should be exercised in extending results to proportion of lactose in the milk.

Crossbred groups had higher total milk production than pure and synthetic breeds. Lactation curves for crossbred ewes, grouped by breed of sire, had a similar pattern. Finnsheep and Rambouillet-sired crossbred ewes produced proportionately 0·23 more milk than ewes sired by Dorset and Lincoln rams. Breed differences in total milk production were observed among the pure breeds. The Suffolk breed was superior in milk production. All breeds, except the Romanov, followed a similar pattern for lactation curves. The Romanov breed produced milk at a relatively low but consistent level throughout the lactation trial.
Plasma metabolite and hormone concentrations as predictors of dairy merit in young Friesian bulls: effect of metabolic challenges and fasting
Authors: Mackenzie D. D. S. , Wilson G. F. , McCutcheon S. N. , Peterson S. W.
Published: September 2010

Responses to metabolic challenges were measured in 8-month-old Friesian bull calves with a view to identifying possible predictors of genetic merit for milk fat production. Seven ‘high’ breeding index bulls (mean breeding index for milk fat = 128·9 (s.d. 4·8) percentage units) were compared with six ‘low’ breeding index bulls (mean 107·3 (s.d. 2·4) percentage units). Bulls were from two selection lines and breeding indices calculated as the average of parental breeding index values.

Challenges involved intravenous injection of the following (dose rates per kg body weight): adrenalin (1 μg); glucose (0·17 g); glucagon (0·175 μg); insulin (0·01 mg); and arginine (40 mg). Blood samples were withdrawn prior to and after each challenge (two challenges daily). Bulls were then fasted for 3 days before being refed.

Relative to the low breeding index bulls, those in the high breeding index group exhibited: (a) greater pancreatic sensitivity to circulating glucose as indicated by increased insulin concentrations following the glucose challenge; (b) more rapid clearance of glucose from plasma following the insulin challenge; (c) reduced sensitivity to the glycogenolytic/gluconeogenic effects of glucagon as indicated by lower blood glucose concentrations following intravenous injection of this hormone; (d) elevated plasma insulin and growth hormone concentrations during the fasting period; (e) elevated plasma concentrations of insulin, glucose and urea during refeeding; (f) no difference in responses to intravenous arginine or adrenalin, or in circulating concentrations of Insulin-like Growth Factor-1 or alkaline phosphatase. Results are consistent with previous observations that metabolic differences between cattle in the Massey University high and low breeding index lines are most evident in the metabolism of glucose and insulin. Metabolic challenges offer a potentially useful means of predicting genetic merit for milk fat production but the conditions under which repeatable differences between the lines can best be demonstrated are yet to be determined.
A note on the effect of variety, type of straw and ammonia treatment on digestibility and on growth rate in steers
Authors: Reid G. W. , Ørksov E. R. , Kay M.
Published: September 2010

Forty Hereford cross steers of 350 kg live weight were allocated to 10 treatments in which straw was offered ad libitum. The straws comprised two varieties of winter barley (Gerbel (G) an Igri (I)), two varieties of spring barley (Corgi (C) and Golden Promise (GP)) and one variety of winter wheat (Norman (N)). Each straw was offered either untreated (with 20 g urea per kg added at feeding), or treated (with 30 g anhydrous ammonia). After 10 weeks the treatments were changed. The mean growth rates for steers receiving the untreated straws were 0·11, 0·13, 0·40, 0·20 and 0·27 kg/day and for treated straws were 0·36, 0·33, 0·61, 0·60 and 0·52 kg/day for G, I, C, GP and N respectively. The straw intakes for untreated straws were 3·4, 3·6, 5·2, 4·4 and 4·6 kg dry matter per day and for treated straws 4·7, 4·8, 5·9, 4·9 and 5·8 kg dry matter per day for G, I, C, GP and N respectively. Chemical and biological measurements were compared as predictors of voluntary intake of straw and growth rate in the steers. Biological measurements were very efficient in predicting performance of the steers while chemical measurements were much less valuable.