bluuebunny/crossref_metadata_2025 huggingface dataset:
Allometric growth patterns of limb bones in rabbits
Authors: Deltoro J. , López Ana M.
Published: September 2010

Relative growth of length and thickness of femur, tibia, humerus and radius-ulna was studied using data from 320 rabbits from both sexes of two lines (New Zealand White and California). A cross-sectional design was used with slaughter points fixed at weekly intervals from 1 to 20 weeks of age. Carcass length was chosen as independent variable and two models were fitted to the data. Model 1 assumed the existence of one allometric change at some moment of the post-natal development and model 2 of a continuous change of the allometric coefficient throughout the experimental period.

Most of the bone measurement showed allometric changes and in all the cases they were not abrupt but continuous. The theoretical and practical implications of the existence of these changes are discussed. The allometric coefficients of all the bone measurements showed a decreasing rate of change except radius-ulna thickness. While the coefficients for bone lengths were positive tending to isometry, for bone thickness they were always negative.
Utilization of the sex-determining region Y gene in beef cattle breeding schemes
Authors: Bishop S. C. , Woolliams J. A.
Published: September 2010

In mammals ‘maleness’, i.e. the presence of testes, is thought to be controlled by a single gene on the Y chromosome. Recently, a candidate gene termed the SRY (sex-determining region Y) gene has been located. If the SRY gene is the gene causing maleness then a transgenic male with the SRY gene on an autosome would produce a greater proportion of male offspring than a normal male. This would be advantageous in situations where male offspring are more valuable than females. Such transgenic males have a reduced probability of propagating their genotype and an effort has to be made to avoid their extinction. This is at the cost of genetic progress which must be made to enable the transgenics to remain competitive with normal males.

In a simulated beef cattle breeding scheme if half of the annual matings were made to transgenics then after 15 years of selection the transgenic males fell the equivalent of 2·6 years of selection behind males in a traditional herd. If all matings were made to transgenics they fell over 9 years behind. Selection for lean food conversion ratio was considered as an example. After 15 years of selection the gain in biological efficiency from more male offspring outweighed the loss from reduced genetic progress only when more than 0·5 of the bulls used in the breeding scheme were normal males. In practice, the difficulty of maintaining a small population of transgenic males along with other costs not included in the calculations suggest that breeding schemes in beef cattle with an SRY transgene would not be practicable without further technology.
The effect of energy and nitrogen supply pattern on rumen bacterial growthin vitro
Authors: Henning P. H. , Steyn D. G. , Meissner H. H.
Published: September 2010

The effect of energy and nitrogen (N) supply pattern on rumen bacterial growth was investigated in vitro. In experiment 1, glucose was was fed to batch cultures of mixed rumen bacteria according to three patterns namely a pulse dose at time zero (P); even increments at 0·5-h intervals (G) or an intermediate pattern (I), whilst N was supplied in excess. In experiment 2, glucose and N (not in excess) were fed to batch cultures according to four patterns namely glucose and N as pulse doses at time zero, (EPNP); glucose as a pulse dose at time zero and N in 24 even increments at 0·5-h intervals (EPNG); glucose in 24 even increments at 0·5-h intervals and N as a pulse dose at time zero (EGNP) or both glucose and N in 24 even increments at 0·5-h intervals (EGNG). Fermentaton was studied over a 12-h period for both experiments.

In experiment 1, bacterial growth efficiency and specific growth rate (39·8,35·5 and 29·9 (g bacterial dry matter (DM) per mol glucose utilized) and 0·33, 0·27 and 0·20 (fraction per h) for treatments P, I, and G respectively) differed significantly between glucose supply patterns. In experiment 2, bacterial growth efficiency and specific growth rate (33·8, 34·7, 25·9 and 22·5 (g baterial DM per mol glucose) and 0·21, 0·18, 0·14 and 0·13 (fraction per h) for treatments EPNP, EPNG, EGNP and EGNG respectively) differed significantly only between glucose supply patterns.

It is concluded that the pattern according to which a given amount of energy becomes available affects bacterial growth efficiency, with the fastest supply rate giving the highest efficiency and that, within accepted levels of N supply, synchronization between energy and N availability may be of less importance to bacterial growth efficiency than the energy supply pattern.
An evaluation of the effects of incisor dentition and of age on the performance of lactating ewes and their lambs
Authors: Dove H. , Milne J. A.
Published: September 2010

Ninety-six Border Leicester × Scottish Blackface ewes, aged 2 to 6 years, grazed perennial ryegrass pastures during lactation. The state of their incisor teeth was assessed at parturition on a scale from score 1 (sound teeth) to score 4 (poor teeth). Their live weights and condition scores during lactation were then related to incisor score and age by regression analysis. Lamb growth was similarly analysed. Herbage intakes and milk production were measured in a subset of 24 ewes.

Ewe live weights were significantly lower, per unit incisor score, by 2·2, 2·5 and 2·1 kg at days 22, 50 and 96 of lactation respectively. In ewes with twin lambs, the equivalent reductions were 1·6, 2·8 and 2·1 kg respectively. Reductions in condition score, whilst still significant, were less marked. After adjusting for the effects of incisor dentition, there was no effect of age on ewe live weight or condition score.

Incisor dentition did not markedly affect herbage intake or milk production, except in measurements at day 53 of lactation, where higher incisor scores resulted in significant reductions in the production of milk and its components. Effects on lamb performance were confined to twins, where live-weight gain to day 50 was reduced by 12·2 g/day, per unit increase in ewe incisor score. This resulted in reductions of 0·7 kg (day 50) and 0·9 kg (weaning) in the live weight of twin lambs.
Effect of the introduction of rams on the pulsatile release of luteinizing hormone and the onset of reproductive activity in ewe lambs
Authors: Al-Mauly N. Z. N. , Bryant M. J. , Cunningham F. J.
Published: September 2010

Pre-pubertal ewe lambs were introduced to rams on 17 August (Tl), 12 September (T2) or 10 October (T3) or isolated from rams until 21 December (Tc) (no. = 13). Blood was taken for progesterone assay three times weekly (no. = 13) from 16 July. Blood was taken for LH assay at 15-min intervals for 8 h (no. = 8) at the time of the introduction of rams and subsequently at the time of further ram introductions. Blood was taken from Tc lambs at each ram introduction. Tl, T2 and T3 lambs ovulated for the first time 16 (s.e. 2·2) days earlier than Tc lambs but only T3 lambs ovulated after and apparently in response to the introduction of the rams. The mean baseline LH levels were higher in Tl, T2 and T3 lambs in comparison with Tc lambs at all sampling periods. The mean pulse frequency of LH secretion was significantly increased by the introduction of rams in T2 and T3 lambs in comparison with Tc lambs. The mean pulse frequency of LH secretion was greater in Tl, T2 and T3 lambs at the October sampling period in comparison to Tc lambs.
A note on the effect of time after feeding on the distribution of nitrogen in the gastrointestinal tract of sheep
Authors: Sekine J. , Kuninishi Y. , Oura R. , Miyazaki H. , Okamoto M. , Asahida Y.
Published: September 2010

The effect of time after feeding on the distribution of nitrogen (N) in digesta from various segments of the gastrointestinal tract was studied in sheep given a diet of chopped hay once daily. Four groups of four animals were slaughtered at 2, 8,16 and 24 h after feeding and digesta were separated into large (>1180μm), medium (300 to 1180 μm) small (45 to 300 μm) and fine particles and liquid (<45 μm) fractions. The N pool in the reticulorumen decreased with time after feeding but post-ruminal N pools changed very little. Changes in N distribution within the reticulorumen reflected reductions in large particles and increases in fine particles and liquid fractions, the intermediate fractions remaining fairly constant.
A note on herbage intake by Greyface ewes on perennial ryegrass white clover swards in the autumn
Authors: Gunn R. G. , Doney J. M. , Smith W. F. , Smith A. D. M. , Sim D. A. , Hunter E. A.
Published: September 2010

The effects on herbage intake of changes of herbage mass associated with different stocking rates were studied in Greyface (Border Leicester × Scottish Blackface) ewes in the autumn. Intake was measured in 5-day periods in late September (PI), late October (P2) and late November (P3) on two established, perennial ryegrass/white clover swards (SI and S2). Both swards had previously been variably stocked to produce areas with a range in herbage masses, some of which were grazed continuously (G) at stocking rates declining from 18 to 6 ewes per ha.

Intake was also measured in P2 and P3 on other areas of the swards which were ungrazed for 6 weeks in September and October (C) and then stocked at 18 ewes per ha. Intakes of dry matter, organic matter and digestible organic matter were 16 g, 10 g and 7·5 g/kg live weight, respectively. Organic matter digestibility was 075 in PI and P2 but declined in P3.

Differences in herbage intake and digestibility arose largely because of differences between the swards in herbage mass, sward height and sward density. Ewes in condition scores > 3·00 in early September had lower intakes at all times than did thinner ewes. Changes in sward management associated with different strategies of use had little long-term effect on herbage intake. Keywords: digestibility, herbage, sheep, stocking rate.
Effect of NDF concentration and physical form of fescue hay on rumen degradability, intake and rumen turn-over of cows
Authors: Susmel P. , Spanghero M. , Stefanon B. , Mills C. R. , Cargnelutti C.
Published: September 2010

During two experimental periods, eight non-lactating, rumen fistulated Simmental cows were given 2 kg/day of a cereal based concentrate and fescue hay ad libitum. The hay differed in neutral-detergent fibre concentration (LNDF: low; HNDF: high) and physical form (L: long; C: coarsely chopped). The rumen degradability of the dietary ingredients and of an extracted soya-bean meal was studied using the polyester-bag method.

The estimated effective rumen degradability <DG) of dry matter (DM) was significantly higher for LNDF than for HNDF hay (0·490 v. 0·401; P < 0·01). The DM DG of the extracted soya-bean meal and the dietary concentrate were higher when incubated with LNDF than with HNDF diets (0·630 v. 0·581, P < 0·05, and 0·541 v. 0·514, respectively).

Chopping the hay significantly increased the daily DM intake for HNDF diets (from 9·9 to 11·6 kg; P < 0·05), while no statistical differences were found between the other diets (10·2 and 9·6 kg, respectively for L-LNDF and C-LNDF diets). Cows given HNDF hay drank less water (42·4 v. 51·7 I/day) and total water consumption, expressed per unit of DM intake, was lower for the HNDF diets (4·1 v. 5·3 I/kg DM; P < 0·01).

Dietary treatments did not affect the estimated rumen turn-over rate of hay (0·027 per h on average, k1), hay post-rumen turn-over rate (0·069 per h on average, k2) or the estimated rumen liquid turn-over rate (0·100 per h on average, kj. The calculated outflow from the rumen was lower for the HNDF diets (159·4 v. 198·7 I/day). The daily amount of estimated saliva secreted did not differ between treatments, although saliva expressed per kg DM intake was significantly lower for the HNDF diets (10·8 v. 14·8 I/kg DM; P < 0·05).

The HNDF diets gave a lower post-feeding rumen pH (6·29 v. 6·58; P < 0·01), a higher concentration of n-butyrate (9·58 v. 8·32 mmol/l; P < 0·05) and a lower concentration of ammonia nitrogen (NH3-N) (80·5 v. 128·5 mg/l; P < 0·05). Of the C4 and C5 iso-acids, the rumen liquid from cows given HNDF diets had significantly lower concentrations of isobutyrate, isovalerate and n-valerate (P < 0·01). Hay physical form did not affect rumen pH, NH3-N and volatile fatty acid concentrations.
A simple method to increase precision or reduce expense in regression experiments to predict the proportion of lean meat of carcasses
Authors: Engel B. , Walstra P.
Published: September 2010

By a combination of complete and incomplete dissections a considerable increase of precision or reduction of expense may be obtained in the construction of a prediction formula for the proportion of lean meat of a carcass from objective carcass measurements. This approach, referred to as double-regression, is demonstrated on data involving dissection of pig carcasses in The Netherlands. Advantages of double-regression relative to ordinary regression with respect to precision and experimental cost are discussed. Expressions for optimal sample sizes at fixed total cost are derived.
A note on the estimation of environmental effects on lactation curves
Authors: Strandberg E. , Lundberg C.
Published: September 2010

A method was suggested that attempts to distinguish between the underlying lactation curve, the effect of season of production, and the effect of time after conception. The composite function was shown to give a better fit than an incomplete gamma function. The estimated parameters of the underlying lactation curve were unaffected by season of calving whereas the parameters of the gamma function were not. Pregnancy started to affect yield 160 days after conception by -0·1 kg/day. The difference between the best season of production (May) and the worst (November) was around 5 kg.
Energy: protein interactions in growing boars of high genetic potential for lean growth. 2. Effects on chemical composition of gain and whole-body protein turn-over
Authors: Rao D. S. , McCracken K. J.
Published: September 2010

The effect of reducing energy intake within the practical range or reducing energy intake without reducing protein intake on chemical composition of gain, whole-body protein turn-over and energy metabolism was studied between 33 and 90 kg live weight with seven replicates of five littermate boar Landrace pigs. Three levels of food intake (ad libitum, 0·90 and 0·80 ad libitum) were used and the dietary protein contents ranged from 250 to 312 g crude protein (CP) per kg dry matter (DM) to equalize protein intake with reduced food intake. All the diets were of similar amino acid composition and were offered twice daily as pellets. There was no effect of dietary treatment on the DM, CP and fat contents (g/kg) of the empty body (EB), but fat content and fat: protein ratio in EB tended to decrease with reduction of food intake or energy intake. The relationship between energy intake and protein deposition was linear and the mean maximum protein retention was 187 g/day. Retention of DM (P < 0·001), protein (P < 0·001), fat (P < 0·001), energy (P < 0·001) and ash (P < 0·01) decreased linearly with reducing food intake or energy intake. The calculated residual heat production was 0·604 MJ metabolizable energy per kg M0·75 per day. The dietary treatments had no effects on composition of longissimus dorsi, fillet, liver, kidney, backfat or kidney fat. The nitrogen flux, nitrogen synthesis and breakdown tended to decrease with reduction in food intake or energy intake though the effects were not statistically significant. Nitrogen accretion decreased significantly (P < 0·05).
A note on the effect of wood cellulose level in protein-free diets on the recovery and amino acid composition of endogenous protein collected from the ileum in pigs
Authors: Leterme P. , Pirard L. , Théwis A.
Published: September 2010

The effect of fibre level in protein-free diets on the recovery and amino acid composition of endogenous protein collected from the ileum in pigs was studied. Although the Heal nitrogen excretion increased slightly with dietary fibre level, no significant difference was observed on the amino acid recovery between diets containing 30, 60,90 or 120 g wood cellulose per kg.
Interrelationships between lack of shading shelter and poultry litter supplementation: food intake, live weight, water metabolism and embryo loss in beef cows grazing dry Mediterranean pasture
Authors: Silanikove N. , Gutman M.
Published: September 2010

The objective of the study was to assess the usefulness of providing shade for beef cows grazing summer dry Mediterranean -pasture and supplemented with a food high in non-protein nitrogen (poultry litter). Two groups of 30 cows each, in the last trimester of pregnancy, were placed on 1 June in two paddocks of similar grazing pressure, topography, vegetation cover and botanical composition. In one of the sub-units the cows had free access to a large shaded area, provided by 10 to 12 large eucalyptus trees, whereas in the second sub-unit, access to shade was denied until 31 August. Respiration rate, used as an index of heat stress, was much higher in the non-shaded cows (102 breaths per min) than in the cows with access to shade (62 breaths per min). In response to the much higher heat stress in the non-shaded cows, total body water and haematocrit value (an index of plasma volume) were higher than in the cows with access to shade. Metabolizable energy (ME) intake was apparently much lower in the non-shaded cows, as reflected in a much higher non-esterified fatty acid concentration in plasma. Consequently, large differences in live weight gradually developed during the course of the trial, the cows with access to shade becoming much heavier than those with no access to shade. An increase in the consumption of poultry litter by the non-shaded cows was interpreted as an effort to reduce internal heat load by avoiding grazing and by preferring food which induces a lower heat increment upon ingestion and digestion. Above-normal serum concentrations of cholesterol and alkaline phosphatase support previous results that the combination of low ME intake and high ammonia load induces a toxic effect on the liver. Although all the cows were pregnant at the onset of the study, successful parturition was recorded in 26 of the 30 cows having access to shade, and in only 20 of the 30 (F < 0·05 by t test) of the non-shaded cows. It is concluded that providing shade for beef cows under summer Mediterranean conditions will reduce the danger of embryonic loss. However, an interaction with metabolic burden, such as ammonia load and a negative energy balance, can make the situation much worse.
Responses of young calves to low ambient temperatures at two levels of feeding
Authors: Schrama J. W. , Arieli A. , Heetkamp M. J. W. , Verstegen M. W. A.
Published: September 2010

Seven groups of five or six Holstein-Friesian male calves were transported to an experimental farm at 2 to 3 days of age. At 6 days of age, heat production (HP) and metabolizable energy (ME) intake were measured for an 8-day period. During this period, calves were exposed to various ambient temperatures: 6, 9, 12 and 15°C. Ambient temperature was constant within days, but changed between days. Calves were fed below (four groups) or near (three groups) the maintenance requirements (290 or 460 kJ ME per kg M0·75 per day).

From 6 to 14 days of age the lower critical temperature (Tc) was 12·5°C and HP increased by 8·4 kJ/kg M0·75 per day per °Cfall in ambient temperature below Tc. Both Tc and increase in HP below Tc were not affected by feeding level. Rectal temperature was lower at low ambient temperatures. The decrease in rectal temperature with ambient temperature was greatest at the low feeding level.

During the experimental period, calves were not in a steady-state regarding energy metabolism. Heat production decreased with time. This decrease was affected by feeding level and ambient temperature. After arrival, the influence of both ambient temperature and feeding level on the energy metabolism of young calves increased with time.
Effect of supplementaryAspergillus nigerphytase in diets for piglets on their performance and apparent digestibility of phosphorus
Authors: Beers S. , Jongbloed A. W.
Published: September 2010

A total of 384 piglets from a three-way cross Yorkshire ♂ × (Finnish Landrace ♂ × Dutch Landrace♀) ♀ in the live-weight range of 11 to 25 kg were used in a feeding trial. The effect of supplementary microbial phytase from Aspergillus niger var. Van Tieghem on performance (average daily gain (ADG), average daily food intake (ADFI) and food conversion ratio (FCR)) and apparent digestibility of total phosphorus (P), in comparison with a non-supplemented basal diet or a diet supplemented with one or two levels of monocalcium phosphate (MCP), were studied.

The piglets were allotted to 12 blocks. Within each block, four experimental diets were offeredad libitumfor a period of 4 weeks i.e. (1) basal diet; (2) basal diet + 1·0 g P, from MCP per kg diet; (3) basal diet + 1·9 g P, from MCP per kg diet; and (4) basal diet + 1450 phytase units (PTU) per kg diet. The diets, with added chromium III oxide as a marker, were cold pelleted without steam at a temperature not above 60°C to avoid a possible inactivation of the phytase. In all diets the ratio calcium: digestible P was intended to be constant.

Adding 1450 PTU of Aspergillus niger phytase enhanced the apparent digestibility of P by proportionately 0·216 when compared with diet 1 and by proportionately 0·100 compared with diet 3. In addition, significantly higher ADG and ADFI and better FCR were noted in pigs receiving supplementary microbial phytase than in pigs on any other treatment. The content of digestible P of the diet with added phytase, however, zvas between the two levels of the diets with added MCP.
Growth rate and growth composition of artificially reared piglets from specific pathogen free sows
Authors: Verstegen M. W. A. , van der Hel W. , Pijls F. J. M.
Published: September 2010

Heat production, energy and nitrogen balances of artificially reared piglets from specific pathogen free sows, housed in a respiratory chamber, were measured over five successive periods of 7 days each from 4 to 39 days of age. The experiment was carried out at an environmental temperature decreasing from 33 to 27°C. The mean weight increased from 1·5 (at day 4) to 11·9 kg (at day 39). Daily rate of gain increased from about 100 g in periods 1 and 2 to 502 g per piglet in the fifth period.

Daily protein deposition, as measured via nitrogen balance, increased from 17 to 96 g; fat deposition increased from about 0 to 100 g. Body composition at the start and end was determined by a comparative slaughter technique. Protein and fat content had a high correlation coefficient with body weight (R2= 0·69 and 0·89, respectively). At birth these values were much lower, 0·24 and 0·01 for protein and fat, respectively.

Nitrogen balance compared with slaughter technique led to an overestimation for protein deposition of proportionately 0·07. Fat gain measured from slaughter was proportionately 0·08 lower than that calculated from energy balance.

Ratio of gain estimated from protein and fat gain with the balance technique relative to that measured ranged between 0·93 to 1·15 in various periods.
Wastage and culling in dairy herds
Authors: O'Connor L. K. , Hodges John
Published: September 2010

Wastage and culling rates in Private Milk Records herds during a three year period, October 1957 to September 1960, were estimated from data collected byfieldsmenduring one week in each month.

Total deaths and disposals among cows fell from 29·3% in 1957–8 to 23·4% in 1959–60 due mainly to reductions in the sales of surplus cows, non-attested cows and reactors to tuberculin. Wastage and culling among cows tended to be higher in winter than in summer. The rate of loss tended to increase in successive lactations and the percentage of animals sold for dairying fell from the third lactation onwards whilst disease, accident and old age became increasingly important reasons for culling.

Total deaths and disposals among heifers fell from 17·3% in 1957–8 t o 11·3% in 1959–60 due mainly to a reduction in the sale of stock for purposes other than dairying as ‘surplus’ or ‘fat’, and to a fall in the numbers sold for dairying for miscellaneous reasons. There was a peak in heifer disposals in early summer.

It is estimated that the average herd life in P.M.R. herds from first calving o t disposal is between 3½ and 4½ years and that average total productive life from first calving to death is between 5 and 6 years.
The supplementation of pig diets with oleandomycin
Authors: Smith W. C. , Adam J. L. , Tonks H. M.
Published: September 2010

A trial is described in which normal rations containing oleandomycin at 12½ and 25 g. per ton of meal and without the additive were given to females and castrates which had previously received creep feed with and without oxytetracycline.

A total of 48 pigs were individually fed on the rations from 50 to 200 lb. live-weight, a restricted scale of intake based on live-weight being adopted.

Between 50 and 100 lb. live-weight rate and efficiency of gain were significantly better in pigs which had not received antibiotic in the creep feed. No other treatment had any significant effect on performance.

Oleandomycin did not influence carcass measurements or dressing percentage. Minimum depth of fat at the mid-back was significantly greater in pigs which had received oxytetracycline in the creep feed while castrates had a significantly greater depth of fat at the shoulder and mid-back compared with females.

Pigs receiving the lower level of oleandomycin had significantly lighter kidneys than the control animals. Other visceral weights were not significantly influenced by the antibiotic, but females had significantly heavier kidneys, spleen and liver weights than castrates.
Genetic change of backfat thickness in the Danish Landrace breed of pigs from 1952 to 1960
Authors: Smith Charles
Published: September 2010

Data from the Danish progeny test reports were used in an attempt to measure the genetic change in backfat thickness in the Danish Landrace breed from 1952 to 1960. Over this period the average backfat thickness of tested pigs fell from 34·2 mm. to 28·5 mm., a change of two standard deviation units.

The method used to measure genetic change depends on the differencein performance in two or more years of progeny from particular sires or dams. Environmental differences between the years are avoided by measuring performance relative to the year mean. However, allowance has to be made for selection among parents on the basis of their first set of progeny records, through adjusting the initial records by theoretical regression factors. The genetic change is then estimated as a function of the difference between the adjusted first progeny records and the records of subsequent progeny groups.

Separate estimates of the genetic change in backfat thickness were calculated in this way from the progenies of sires and of dams at each of the three stations. These were in general agreement and indicated that there was some genetic improvement in backfat thickness in the Danish Landrace from 1952 to 1960 but that not all of the observed change was genetic change. The overall estimate of the genetic change was —015±0·10 mm. per year and this represented about one-fifth of the observed change. Other less critical results are also given and these lead to the same general conclusion.
The effect of selection for litter size and litter weight at weaning in mice maintained on two diets
Authors: Dalton D. C. , Bywater T. L.
Published: September 2010

An experiment was carried out with mice over 24 generations to measure the response obtained to selection for litter size and litter weight at weaning on two dietary regimes designated normal and diluted. In addition, control groups bred by random mating were maintained on each diet. The stock were maintained on the diets from generation 0–3 after which time selection for the traits started and continued up to generation 17. After generation 17 for a further 6 generations, all selection stopped and half of each group was switched on to the other diet, while the remaining half continued as before.

No significant response was obtained to selection for either litter size or litter weight at weaning.

The diets provided did not bring about a differential response to selection for the traits, and the response to the dietary switch was small and temporary in its effect.

Due to strong maternal effects and low heritability, little genetic improvement was obtained by selection for litter size and litter weight at weaning in these mice.
The effect of plane of nutrition on the carcasses of pigs and lambs when variations in fat content are excluded
Authors: Elsley F. W. H. , McDonald I. , Fowler V. R.
Published: September 2010

1. From a review of the literature it has been shown that there are two opposing views regarding the best method of interpreting growth data, which arise from conflicting opinions as to the role of fat deposition in the growth of the animal.

2. Data of McMeekan and Palsson and Verges have been re-analysed and their own results are compared with results obtained when the effects of variation in fat content are eliminated.

3. No evidence has been found of any effect of plane of nutrition on the total weights of bone and muscle relative to the weight of bone plus muscle together.

4. The weight of bone plus muscle in the head and neck was increased relative to the total weight of bone plus muscle during periods of restricted nutrition. Apart from this there was no clear evidence of a relationship between the order of maturity of the joints and their relative retardation of development.

5. Huxley's allometry equation was found appropriate for standardising the measurements, and the exponent was taken as a numerical expression of the relative maturity of each tissue or part.
Modification of fleece development in Blackface sheep by variation in pre- and post-natal nutrition
Authors: Doney J. M. , Smith W. F.
Published: September 2010

1. Wool production and fleece structure were studied by fibre analysis in six groups of lambs subjected to different pre- and post-natal levels of nutrition. Samples were taken at 6, 12, 28 and 48 weeks of age.

2. Pre-natal limitation (twin pregnancy) reduced the number of secondary fibres present at birth but, providing post-natal nutrition was adequate, this difference had disappeared by 6 weeks. There were no permanent effects on fibre number, wool production or fleece structure.

3. Severe post-natal restriction of feed intake during the first few weeks of life had a marked effect on the development of the secondary fibre population, on wool production and on the birthcoat shedding cycle. The effects persisted beyond the period of nutritional limitation but had disappeared by 12 months of age.

4. The results are discussed in relation to the normal development of the adult Blackface fleece.
Social behaviour of domestic animals. VI. A note on some characteristics of “runts” in pigs
Authors: McBride G. , Wyeth G. S. F. , Hodgens N. W.
Published: September 2010

In young pigs, it is common to find individuals which grow appreciably slower than their litter-mates. Such “runts” are an important cause of economic loss in the pig industry. Extreme examples are easily recognisable but an adequate definition of what constitutes a runt is more difficult. It is, however, possible to separate slow growing pigs from the remainder and compare them in a number of ways. During the course of a study involving routine observations on the behaviour and growth of piglets, data were obtained which made it possible to compare slow growing pigs with others. It is the aim of this study to tabulate these differences and to relate them to the weights of piglets at birth.
Crossbreeding and litter production in British pigs
Authors: Smith C. , King J. W. B.
Published: September 2010

The litter production of various purebred and crossbred groups of pigs were studied in data collected from 1959 to 1961 on some 34,800 litters recorded on over 800 farms in Britain. A least squares analysis was performed to obtain within-farm estimates of performance for five litter traits in sixteen specified breeding groups and to analyse the total variation in litter performance.

The ranking of the purebreds and crossbreds is presented. In general there was a lower mortality in crossbred litters which had 2 % more pigs at birth and 5 % more pigs at weaning than purebred litters. The total litter weight at weaning was 10% greater in crossbred litters. Crossbred sows showed more heterosis with 5 % more pigs at birth, 8 % more pigs at weaning and an advantage of 11 % in total litter weight at weaning.

Farm differences accounted for a major portion of the total variation n i litter production, 8–9% for litter numbers and 15–25% for litter weights. On the other hand the interactions of farms and breeding groups, though highly significant, contributed only 1–2% of the total variation in litter production.
Mortality among twin and single lambs
Authors: Purser A. F. , Young G. B.
Published: September 2010

The effects of maternal age and birth weight on survival of twin lambs has been studied in a Blackface and a Welsh Mountain flock. The time of death was also investigated for both singles and twins.

Twin mortality was higher than mortality of singles, mainly due to the lower average birth weight of twins. Twin mortality declined with increasing birth weight although it showed a tendency to increase at the top of the scale. Weight for weight, mortality was similar for singles and twins. Twin mortality declined with increasing age of ewe in a very similar pattern to single mortality.

Lamb mortality was heavy at birth and during the first 14 days of life with only 30% of the mortality occurring after this age. Approximately 12% of the dead lambs were stillborn. Among singles a similar proportion died as a result of difficult births, but this cause of mortality was rare in twins.

Stillbirth mortality rates were very high for very small birth weights and declined with increasing weight of lamb. Difficult births, on the other hand, increased with increasing birth weight. The association of birth weight with mortality was particularly important in the first 14 days of life but thereafter its significance was less.

Although mortality in lambs of younger ewes was heavier than that of older ewes, similar causes of death operated. Younger ewes, however, having lower birth weights tended to have more stillbirths but few losses due to difficult lambings.
A comparison of reciprocal progeny tests amongst Holstein-Friesian sires from Canada and the United States of America
Authors: Hinks C. J. M. , Zarnecki A.
Published: September 2010

The test proofs of 29 Holstein-Friesian sires (12 Canadian and 17 US) with milking daughters in both Canada and the USA were compared. The mean test rating of the Canadian and US sires respectively was 125±74 kg and 265±57 kg higher in Canada than in the United States.

These results were supported by others obtained in milking trials in Denmark and West Germany.

The fat percentage of US Holstein progeny was higher in Canada and Europe than in the USA, suggesting that the low fat percentage of the US Holstein in its country of origin cannot be attributed simply to lack of genetic potential.

It is suggested that the US Holstein be considered as a substitute for the Canadian for the improvement of milking performance in European Friesian populations.
Factors affecting birth weight of Santa Gertrudis calves
Authors: Willis M. B. , Wilson A.
Published: September 2010

Birth weights of 568 Santa Gertrudis calves by 15 sires out of 111 different dams over a 14-year period were obtained from a herd in Cuba. Year of birth, season of birth, sex of calf, sire and dam all had highly significant influences upon birth weight but there was no effect of dam age or parity. Calf inbreeding ranged from 0 to 25% and led to a decrease of 012 kg in weight for each 1% increase in inbreeding. Calves surviving to weaning or dying between birth and weaning were of similar mean weight. Calves dying at birth were some 4·53 kg above the overall average of 38·59 kg. Sire effects covered a range of some 9·85 kg in birth weight. Heritability of birth weight estimated from an intra-class correlation between paternal half-sib groups was 0·67. Repeatability estimates were of the order of 0·22 from intra-class correlation and 0-24 on the basis of regression of later on earlier records. The overall least squares mean weight of 38-59 kg was several kg higher than previous estimates in the literature.
Comparative studies on the effects of feeding different types of oils at two levels on the performance and carcass characteristics of growing pigs in the tropics
Authors: Babatunde G. M. , Fetuga B. L. , Oyenuga V. A.
Published: September 2010

Two feeding trials involving 105 pigs weighing approximately 14·5 kg were carried out to investigate the effects of palm oil, groundnut oil, locally produced lard, and beef tallow at 2·5% and 5% of the diet, on performance characteristics and carcass quality. The pigs were of the Yorkshire and Yorkshire × Landrace crosses, and of both sexes. The 23% protein basal diet had no oil added, and the other eight diets were made from the basal diet by the weight-for-weight substitution of the maize with the 2·5% or 5% levels of the four oil types. The results of the two trials were combined and considered as a 2 × 4 factorial experiment (2 levels and 4 types of oil) with the basal diet serving as the control. Only the pigs in the second trial were slaughtered and their carcasses graded at the average live weight of 57±1 kg. Correlation and regression analyses were made on some performance and carcass characteristics, on the average daily digestible energy intake. Results showed no significant treatment differences in the average daily gains, average daily feed intake, and average daily digestible energy intake, but there were highly significant treatment differences in feed consumed/kg of gain and average digestible energy (DE) consumed/kg of gain (P<0·01). None of the carcass quality parameters showed any significant treatment differences. Both the correlation and the regression coefficients for the average daily gain on DE intake were highly significant for all the oil types and levels, but the relationships were low and non-significant when the feed/gain ratio, average backfat thickness and the average percentage of lean cuts were regressed on the daily DE intake.
A note on the heat production of fasting pigs in the range 16 to 96 kg live weight
Authors: Holmes C. W. , Breirem K.
Published: September 2010

The results of earlier work by Breirem have been reanalysed, and some recent results are presented. Breirem's results indicated that for pigs of 16 to 96 kg live weight and fasted for 4 to 9 days, heat production (HP) was related to live weight (LW) according to:

HP = 229 LW0·512

which could be converted to:

HP = 185 LW0·569

This equation gives values for fasting heat production which are about 20% higher than those usually estimated from Breirem's results on pigs of 16 to 196 kg. The recent results, for pigs fasted for 24 hr, were slightly higher than would be indicated by the latter equation. If the values derived from the reanalysis of Breirem's data are related to several estimates of the energy required for maintenance by pigs, values for km% between 87 to 103% are obtained.
Studies on the intake and utilization of wet feed by calves
Authors: Fitzgerald J. J. , Kay M.
Published: September 2010

A latin square design with three periods of 3 weeks was used to measure the dry-matter intake, live-weight gain and water intake of 12 British Friesian calves offered an all-concentrate diet ad libitumin wet form. The diets contained 30% (B), 20% (C) or 15% (D) dry matter. A further six calves were given the same diet in dry form (A) throughout the experimental period. Digestibility and nitrogen balance were measured on four calves on each treatment at the end of the experimental period. In addition, two Ayrshire calves, each fitted with a permanent abomasal cannula, were used to study the site of digestion of the feed when given in dry or wet form.

The mean dry-matter intakes of the calves given the dry and wet feeds were 75·5 and 80·8 g/kg W0·75 per day respectively and mean daily live-weight gains were 849 g for the calves on both types of feed. The mean dry-matter intakes of the calves given the wet diets were 80·9 (B), 81·2 (C) and 75·5 (D) g/kg W0·75 per day, and the live-weight gains (g/day) were 857 (B), 879 (C) and 812 (D). None of these differences were significant. The intake of water by the calves was significantly increased by reducing the dry-matter content of the diet. The form or dry-matter content of the diet offered had no effect on the digestibility of dry matter (76·1%), organic matter (77·9%), energy (75·8%) or crude protein (75·8%) or on nitrogen retention (32·5% of N intake).

The rumen was the main site of digestion for all Tour diets and an average of only 7% of dietary starch passed undigested through the abomasum.
Model responses of the growing pig to the dietary intake of energy and protein
Authors: Whittemore C. T. , Fawcett R. H.
Published: September 2010

A simple model is described which enables the prediction of the magnitude and direction of the responses of growing pigs to different energy and protein intakes. The model calculates daily live-weight gain from the conversion of the dietary supply of crude protein and energy into protein, lipid and ash in the body of the growing pig. Values were also determined for the energy and protein balances, the composition of the body and the efficiency of feed conversion. The model was formulated with factors drawn from published findings and validated by comparison with independent feeding trials.
Optimum replacement rates in animal breeding
Authors: Ollivier L.
Published: September 2010

The expected annual selection response is a function of selection intensity (i), generation interval (t) and precision (p) of breeding value estimation. These three parameters may, under certain conditions, be reduced to functions of one variable, y, the mean age of breeding animals at culling, which is a simple function of the annual replacement rate. When the number of breeding males and females are different, i and t become functions of two variables ym and yf, the mean ages of males and females at culling. The values of y (or of ym and yt) giving the maximum selection response are established for different domestic species: for individual selection, where the ratio i/t is to be maximized, for selection on a repeatable criterion connected to female reproduction (prolificacy, milk or egg production), where the maximum of ip/t is to be determined, and for male progeny-testing. The results show that, the more prolific a species is, the more rapid the renewal of breeding animals must be and that the renewal should be more rapid for males than for females, particularly in species of low prolificacy. When selecting on female performances which are repeated in time, the optimum renewal rate of females is lowered relative to individual selection on a criterion measured once. Numerical values have been calculated for different species, with given reproduction parameters for each one.
Some aspects of competition between sheep for supplementary feed
Authors: Arnold G. W. , Maller R. A.
Published: September 2010

Competition for oat grain between sheep grazing on scant, poor quality pasture was studied in three flocks of sheep. A daily feed of 450 g per head was fed in troughs with the space per sheep varying from 4 to > 50 cm. Records were taken of sheep behaviour during the first 3 min of feeding.

There was no fighting in the competition for feed, but dominance of individuals and of groups of sheep occurred. With abundant trough space, certain sheep led the way to the feed trough and were termed leaders, but ‘leadership’ was a characteristic unrelated to competitiveness during feeding. With restricted trough space most sheep raced to the feed trough at feeding time. The rate of disturbance of the sheep from the feed trough increased with decreased space per sheep, particularly below 12 cm/sheep. As the rate of disturbance increased a progressively greater proportion of sheep stopped competing for feed and became non-feeders. Neither the rate of disturbance of the sheep nor the proportion not feeding was related to body weight, but these were largely individual characteristics of sheep.

In a flock of mixed age Merino wethers, the 1-year-old and 7-yearold sheep were the least competitive, while in a flock of wether sheep of seven different breeds but of similar age, Merinos were least competitive.

From these experiments it is suggested that a minimum trough space of 16 cm be allowed when daily grain supplements are fed to grazing sheep.
The effect of dietary crude protein concentration and time of weaning on milk production and body-weight change in the ewe
Authors: Robinson J. J. , Fraser C. , Gill J. C. , McHattie I.
Published: September 2010

Twenty-seven North Country Cheviot ewes, each carrying twin foetuses and having a mean body weight at 6 weeks prior to parturition of 81 kg were individually penned and offered a constant daily intake of 16·75 MJ metabolizable energy during the last 6 weeks of gestation. At parturition the ewes were allocated to one of three dried grass/concentrate diets containing (1) 10·3, (2) 13·6 or (3) 16·9 % crude protein (CP) and 10 MJ metabolizable energy (ME) per kg. The mean daily CP intakes for diets 1 to 3 were 273, 340 and 415 g respectively and the mean daily ME intake was 25 MJ. Within each level of dietary CP intake the lambs were weaned at either 25, 35 or 41 days of age.

There were no significant diet × stage of weaning interactions in milk yield or ewe body-weight change during lactation. The mean daily levels of milk production were 2·4, 2·9 and 3·1 kg for diets 1 to 3 respectively. The corresponding values for ewe body-weight loss were 118, 170 and 265 g per day. When the diet contained 13·8% CP the incremental increase in milk production per unit increase in protein intake was 4·2 g/g. This gave an incremental increase in lamb growth rate of 0·79 g/g and was equivalent to the associated incremental increase in ewe body-weight loss.

A reduction in the concentration of CP in the ewes' diet when the lambs are 3 weeks of age may be a useful practical procedure for decreasing milk production and for reducing the body-weight loss of the ewe in a frequent breeding system.