bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic and environmental effects on age at first calving and calving interval of naturally bred Boran (zebu) cows in Ethiopia
Authors: Haile-Mariam M. , Kassa-Mersha H.
Published: September 2010

Twenty-four years of data from a Boran cattle breeding and improvement ranch in the Rift Valley of Ethiopia were used to study the influence of genetic and environmental factors on age at first calving (AFC) and calving interval (CD using an individual animal model.

The mean AFC and Cl were 41-8 months and 442 days, respectively. The h2 values for AFC were 0·062 and 0·075 when estimated on the original and selected data, from which cows that did not calve after 5 years of age were deleted, respectively. The h2 values for CI were 0·037 and 0·043 when estimated on the original and selected data, from which cows with AFC higher than 5 years and CI longer than 2 years were deleted, respectively. The corresponding c2 values (ratio of permanent environmental variance to total) were 0·031 and 0·028 for the respective data sets. Parameter estimates of the original data from bivariate analysis were 0·012 (h2), 0·065 (h2), -0·054 and -0·176 for first CI, AFC, their genetic and environmental correlation, respectively. The h2 values estimated in a bivariate analysis of the first three CIs varied between 0·002 and 0·093. Year and season had significant effects on both traits. The annual genetic change for both traits was not significant while the solutions for year effects were highly variable. The regression of the solutions of year effects for AFC on year showed that it increased by about 10 days while the variation in CI was due to random year to year fluctuation.
Seasonal variation of voluntary food intake and metabolic rate in three contrasting breeds of sheep
Authors: Iason G. R. , Sim D. A. , Foreman E. , Fenn P. , Elston D. A.
Published: September 2010

Voluntary food intake (VFI) of chopped timothy hay and metabolic rate were each measured in each month of the year in six non-breeding ewes of each of three breeds. Metabolic rate was measured using indirect calorimetry over a range of food intakes and adjusted for intake to an estimated maintenance metabolic rate (MMR). The breeds compared were the Dorset Horn (DT), Scottish Blackface (BF) and Shetland (SH), the first being less seasonal in reproductive and other characteristics than the other two which are hill or northern latitude breeds. There was significant overall variation between months in VFI which was higher in the summer (July to September) than in the winter (December to February) months (P < 0·001). There was a significant breed × month interaction (P < 0·01), the seasonal effect being most strongly observed in the BF and SH ewes, whose VFI in summer was proportionately 0-1 greater than the year-round mean but was 0-1 lower in the winter. The DT ewes showed much less seasonal variation in VFI. There was no overall difference in VFI between breeeds (DT: 43-7; BF: 49-5; SH: 48-1 g dry matter per M075 live weight per day, P > 0·1). Although MMR varied significantly between months (P < 0·001), there was no systematic variation between summer and winter. There was no significant breed × month interaction, but the MMR differed significantly (P < 0·001) between breeds giving a high overall MMR in BF (DT: 322-7; BF: 356-6; SH: 324-5 kf/kg M0·75 per day). No significant correlation existed (P > 0·05) between the monthly mean MMR and VFI in any of the breeds. The causal relationship between seasonal cycles of basal metabolic rate and VFI is questioned.
Nutrient partitioning in Merino rams with different wool growth rates
Authors: Cronjé P. B. , Smuts M.
Published: September 2010

The aim of this experiment was to determine whether there is any physiological basis for concerns that selection for fleece mass may decrease fitness by increasing the partitioning of nutrients to wool at the expense of other body functions.

Forty-five Merino rams (24 months old) were given food at an ad libitum and a maintenance level of nutrition. Animals were grouped into high, average or low clean fleece growth-rate categories on the basis of measurements made during the ad libitum feeding period. During ad libitum feeding, high producers grew proportionately 0·42 more clean fleece, and deposited proportionately 0·36 more energy and 0·42 more nitrogen (N) as greasy fleece than average producers. This was achieved by partitioning a higher proportion of N consumed to wool (0·08 v. 0·06), and not by increased energy or N retention. High producers adapted to the maintenance diet by decreasing clean wool growth rate proportionately by 0·32. There were no differences between high and average wool producers in clean wool growth rate or the percentage of N or energy intake partitioned to wool at the maintenance level of feeding. Although there were no differences in initial live mass between groups, low producers gained proportionately 0·45 more live mass during the experiment than average producers.

It was concluded that Merino rams of high clean-wool production potential are not more efficient, but partition more of the available nutrients to wool production at the cost of body tissue deposition.
Prediction of lean meat proportion in pig carcasses and in the major cuts from multiple measurements made with the Hennessy Grading Probe
Authors: Hulsegge B. , Sterrenburg P. , Merkus G. S. M.
Published: September 2010

Measurements were carried out on 200 selected carcasses in order to investigate whether single or multiple site measurements could provide an accurate estimation of the lean meat proportion in the carcass and the major cuts i.e. ham, shoulder, loin and belly. Fat measurements were taken with the Hennessy Grading Probe II at 17 sites on the left side of the carcass, and muscle measurements at four of these sites. The day after selection 200 left sides were dissected according to the simplified European Community (EC) reference method.

Fifty of these left sides were further dissected according to the full EC reference method. The use of multiple site measurements, compared with a single site measurement, only slightly reduced the residual s.d. of the estimated lean meat proportion in the carcass and the major cuts, e.g. addition of a second site measurement reduced the residual s.d. values by 0·3 to 1·3 gjkg only. The measurement between the 13th and 14th thoracic vertebrae, 7 cm off the dorsal mid line, appeared to be the best single estimator, of the sites probed, for lean meat proportion in the carcass and in the major cuts. Prediction of lean meat proportion in the belly appeared to be problematic (residual s.d.> 29 g/kg).

During the experiment two problems emerged. Firstly, the algorithm, which calculates fat and muscle thickness from the optically measured tissue profile, was not appropriate for every site. Secondly, the definition of the probing position did not always coincide with the anatomical position of the intended superficial layer of muscle underneath the subcutaneous fat.
Lactational performance of Giza White rabbits and its relation with pre-weaning litter traits
Authors: Khalil M. H.
Published: September 2010

An experiment was carried out in Egypt using Giza White rabbits to investigate their lactational performance and to estimate the repeatabilities of milk yield and other litter traits. Data on 325 litters from 115 does fathered by 40 sires were used. Lactation traits involved milk yields during the first 7 days, 21 days and 35 days. Litter traits included litter size and weight at birth, number born alive, litter weight and gain at 21 days, litter size and weight at weaning and pre-weaning litter gain. Linear mixed models were used for analysing such data.

Phenotypic variation in milk yield was relatively high during the first 7 days, and decreased thereafter with advance of lactation stage. Year-season effects were significant for most litter traits, while month of kindling affected litter weight and gain at 21 days and milk yield during the first 7 days (P < 0·05 or P < 0·001). Litters kindled during winter had the highest milk yield compared with litters kindled in the other seasons. Milk production, litter size and weight and litter gain had curvilinear relationship with parity (P < 0·05 or P < 0·001). Sire of doe had no significant effects on litter traits studied. Repeatabilities of all traits were low and ranged from 0·001 to 0·134. Litter size and weight at birth were residually correlated with milk yield. Litter weight and gain at 21 days were significantly correlated with the lactational performance of the doe (P < 0·001).
Comparative growth in relation with the age assessed by skeletochronology in two mullet fishes of genus Liza
Authors: Patón D. , Cardona L. , Gisbert E.
Published: September 2010

We propose a new method for determining age in mullet fishes taking the thoracic spines as material of analysis. The relations length-age and tueight-age were evaluated by von Bertalanffy and logarithmic regressions. Both methods closely agreed with the observed data but the von Bertalanffy's model showed the best R2 values in both species. Two parameters related to growth speed; the K coefficient of von Bertalanffy's model and the slope of logarithmic regression, were higher in Liza ramada than in Liza saliens. However, our results show that mullet have both high rates of size-growth and weight-production, in comparison with other marine fishes.
True and apparent metabolizable energy values of lucerne and yellow maize in adult roosters and mature ostriches (Struthio camelus)
Authors: Cilliers S. C. , Hayes J. P. , Maritz J. S. , Chwalibog A. , du Preez J. J.
Published: September 2010

In an experiment involving 30 roosters and 15 mature male ostriches the apparent metabolizable energy (ME) values, corrected for zero nitrogen retention (AMEn), were determined by balance method for maize and lucerne meal. A group of 10 roosters received maize as the sole dietary component. For the second group of 10 roosters a blend of 750 g/kg maize and 250 g/kg lucerne was prepared. The diet of the third group consisted of 500 g/kg maize and 500 g/kg lucerne meal. The ostrich basal diet consisted of 1000 g/kg lucerne, and was blended in the ratios 50 lucerne: 50 maize and 25 lucerne: 75 maize. Each dietary treatment was given to five ostriches, individually housed in metabolism crates. Food intake and excreta collection was carried out over a period of 5 days after the ostriches had been accustomed to the diets for 7 days. For roosters food intake and excreta collection lasted for 72 h after an adaptation period of 24 h.

The AMEn value for maize was 14·49 (s.e. 0·046) MJ/kg in roosters while in ostriches AME,, values of 14·3 (s.e. 1·81) and 14·5 (s.e. 0·845) MJ/kg for the 500 g/kg inclusion and 250 g/kg inclusion respectively were found.

In roosters lucerne meal yielded AME,, values of 4·49 (s.e. 0·506) and 4·05 (s.e. 0·321) at 250 g/kg and 500 g/kg inclusion levels respectively. For the ostriches a value of 8·9 (s.e. 0·755) Mj/kg was found for lucerne.

True ME, corrected for zero nitrogen retention, (TMEJ was computed by regressing gross energy output on gross energy input over all feeding levels. Maize yielded values of 14·65 (s.e. 0·0455) and 14·9 (s.e. 0·351) for roosters and ostriches respectively while corresponding values for lucerne were 4·03 (s.e. 0·118) and 8·6 (s.e. 0·296) MJ/kg.

It was concluded that the ostriches were capable of digesting a high starch diet such as maize to the same extent as adult roosters but ostriches were capable of digesting a high fibre ingredient such as lucerne meal much more efficiently.
Effects of energy allowance and cimaterol feeding during the heifer rearing period on growth, puberty and milk production
Authors: Barash H. , Peri I. , Gertler A. , Bruckental I.
Published: September 2010

Twenty-one 6-month-old Israeli Holstein heifers were used to determine the effect of three 6-month feeding regimes on growth, blood concentration of insulin, prolactin and insulin-like growth factor-1 (IGF-1), attainment of puberty and milk production during first lactation. Feeding regimes were as follows. (1) Restricted: the heifers were given food during months 1, 2 and 4, 5 of an experimental period, to support live-weight (LW) gain of 0·35 and 0·50 kg/day, respectively and during months 3 and 6 the heifers were given food to support compensatory growth. (2) Control: the heifers were given food to support LW gain of 1·0 kg/day. (3) Control + C: the heifers were given the same as the control, with a daily supplement of 0·05 mg/kg LW cimaterol (C) for 4 months. The total LW gain of the restricted heifers during the 6 months of the trial was significantly lower than that of the control heifers. Cimaterol improved growth rate only during the first 2 months of its application and its withdrawal was associated with severe LW gain retardation. The feeding regime employed in the restricted treatment was associated with a significant reduction in serum concentrations of insulin, prolactin and IGF-1 during the first restricted phase, followed by an elevation in the first compensatory phase. During the second restriction-compensation cycle, only the serum concentration of prolactin was significantly reduced. Cimaterol addition was also associated with a reduced blood concentration of the hormones. The animals in the restricted, control and control + C groups attained puberty at LW of 249·2, 277·6 and 304·9 kg (P<0·05), respectively. No effect of the treatments on milk yield was observed. The effect of the feeding regimes on skeletal growth and on metubolizable energy efficiency for growth is discussed.
Effect of nitrogen supply on nitrogen and energy metabolism in lactating sows
Authors: Everts H. , Dekker R. A.
Published: September 2010

In 56 balance trials sows received diets in pregnancy containing (g/kg diet) either 24·7 nitrogen (N) (C) or 16·7 N (L) followed by diets in lactation containing (g/kg dietary dry matter) either 28·5 N and 8·4 lysine (C) or 32·8 N and 10·3 lysine (H). N and energy balance during lactation (day 4 to 25) were made during three successive parities (23, 17 and 16 sows in parities 1,2 and 3, respectively). Retention in piglets was calculated from their body composition at weaning.

Mean daily litter gain was 2·72 kg/day and was not affected by the dietary treatments. Mean body-weight loss of sows was 0·67 kg/day and was lower only in parity 2 on lactation treatment H compared with lactation treatment C. N retention was less negative on lactation treatment H than on lactation treatment C (significant in parity 1) and N retention was less negative on pregnancy treatment L than on pregnancy treatment C (significant in parity 3). Fat mobilization on lactation treatment H was higher than on lactation treatment C (significant in parities 2 and 3). The proportion of energy mobilized as protein to the total energy mobilization was significantly lower on lactation treatment H compared with lactation treatment C. Estimated daily N, lysine and Heal digestible lysine requirements for first parity lactating sows were 162 g, 48 g and 37 g respectively. For second parity sows 179 g, 54 g and 42 g and for third parity sows 185 g, 56 g and 43 g. N excretion during lactation was proportionately about 0·6 of ingested N. This resulted in an N excretion of about 2·3 kg N during a 25-day lactation period. After correction for differences in litter size, body weight of sows, daily litter gain and N mobilization increased with parity number.
Some effects of level of feeding and body condition upon sperm production and gonadotropin concentrations in the ram
Authors: Alkass J. E. , Bryant M. J. , Walton J. S.
Published: September 2010

1. In two experiments. Scottish Blackface and Finnish Landrace ♂ × Dorset Horn ♀ rams were housed in light-proof buildings and subjected to a constant 10-h light: 14-h dark photoperiod 70 days before and during the experiment. In experiment 1, four rams from each breed type were given either 750kJ/MJ(L) or 1250 to 1500 kJ/MJ(H) of their maintenance requirement for 20 weeks. In experiment 2, four rams of each breed were given either 750kJ/MJ(T) or 2000 kJ/MJ(F) of their maintenance requirement for 20 weeks, and were then fed to maintain live weight for a further 10 weeks. Daily sperm output in the urine and scrotal circumference were measured in both experiments. Various characteristics of ejaculated semen were measured in experiment 1. Sequential blood samples were collected from the rams on both experiments and assayed for follicle stimulating hormone and luteinizing hormone. At the end of each experiment the rams were slaughtered, and their testes, epididymides and anterior pituitary glands recovered.

2. In Experiment 1, the L feeding level depressed progressively the numbers of sperm voided in the urine, scrotal circumference, and the concentration and total numbers of sperm in ejaculated semen. The testes and epididymides of L rams were lighter (P<0·01) and fewer sperm were recovered from the reproductive tract than i n H rams (P<0·01). The pituitary glands were lighter (P<0·05) and contained less luteinizing hormone (P<0·01) but amounts of follicle stimulating hormone similar to the H rams. Plasma luteinizing hormone levels were lower in L than in H rams at 20 weeks (P<0·05).

3. In experiment 2, the T rams showed a progressive depression of numbers of sperm in the urine and scrotal circumference, such that at 20 weeks differences between F and T treatments were statistically significant (P<0·05 and 001 respectively). Subsequently, some recovery occurred which, with a reduction in these measures on F treatments, led to there being no statistically significant difference at 30 weeks. There were no statistically significant differences between F and T treatments in testes and epididymes weights, total number of sperm in the tract, and anterior pituitary weight, follicle stimulating hormone and luteinizing hormone content.
Lactational oestrus in the sow 2. The influence of group-housing, boar presence and feeding level upon the occurrence of oestrus in lactating sows
Authors: Rowlinson P. , Bryant M. J.
Published: September 2010

A 2×2×2 factorial experiment investigated the effect on lactational oestrus in sows of housing system (group or singly housed; G v. S), boar presence (boar present or absent; B v. N) and feeding level (ad libitum or restricted; A v. R). All treatments were imposed from day 20 post partum until weaning at day 42. A total of 183 Camborough hybrid female pigs were used, providing between 21 and 24 animals within each cell in the experimental design.

The occurrence of oestrus during lactation was observed as: 0·40 for G compared with 0·10 for S (P<0·01); 0·36 for B compared with 0·14 for N (P<0·05); and 0·28 for A compared with 0·21 for R (NS). The only treatment in which a high proportion of sows (0·78) showed oestrus was the combination G-B-A. Oestrus occurred during lactation on average 11 -4 days after imposing treatments, on average at day 20 post partum and 31·6 days after farrowing, and no significant differences were apparent between treatments. Individual piglet and overall litter weight gains were significantly reduced on G compared with S treatments (P < 0·01).

Sow food intake was greater for the S compared with G, for N compared with B, and A compared with R treatments (P<0·001). Sows on the R treatment lost significantly more live weight than the A sows between days 20 and 42 (P<0·001). Singly-housed sows also lost more weight than group-housed sows between farrowing and day 42 (P<0·001), mainly because of losses occurring before day 20.
The influence of formaldehyde application at ensiling and of supplementation with urea or maize starch on the utilization by calves of ryegrass and red clover silages
Authors: Kaiser A. G. , Osbourn D. F. , England P.
Published: September 2010

Primary growths of perennial ryegrass and red clover were ensiled with formic acid (2 1/t fresh crop), o an equal quantity of formic acid together with formaldehyde (46 or 49 g/kg crude protein in the ryegrass or red clover respectively). The four silages were offered ad libitum to 12 groups, each of five British Friesian steer calves, either alone or with urea or maize starch supplements at 18·4 or 185·2 g/kg total dry-matter intake respectively.

Digestible organic matter and digestible energy intake, live-weight gain, carcass weight, nitrogen retention and all digestibility measurements were higher on the ryegrass silages than on the red clover silages. However, dry-matter intake was higher on the red clover silages.

Formaldehyde treatment reduced lactic and total acid content, and protein degradation in the silages. It also increased intake, live-weight gain and nitrogen retention on ryegrass but not on red clover, the effect being greater when the urea supplement was given. Digestibility measurements were depressed by formaldehyde treatment, although cellulose digestibility was only depressed in the ryegrass silage.

Supplementation with starch depressed silage intake and nitrogen and cellulose digestibility, but increased dry matter, organic matter and energy digestibilities, digestible organic matter and digestible energy intakes, live-weight gain and carcass weight. The positive intake, live-weight gain and carcass weight responses were greater on the silages treated with formic acid, while the digestibility and the live-weight gain responses were greater on the red clover silages. Starch supplementation did not improve nitrogen retention.

The different animal production responses to formaldehyde treatment on the ryegrass and red clover silages are discussed.
A further study of a rigid grazing management system for dairy cows
Authors: Marsh R. , Campling R. C. , Holmes W.
Published: September 2010

1. An experiment was conducted with dairy cows over two grazing seasons to investigate the feasibility of fixed rotational grazing. Each year a comparison was made between treatment A, which consisted of four equal paddocks grazed for 1 week and rested for 3, and treatment B, which contained five paddocks grazed for 1 week and rested for 4. The influence of the length of the rest periods on output per hectare and per cow was measured. Within each paddock approximately one-seventh of the area was allocated daily to each treatment group, there were no back fences and the paddocks were not topped or harrowed. Stocking rates were identical on both treatments at all times at 6·2 cows per ha throughout 1964; 7·1 cows per ha for weeks 1·9 inclusive and 6·2 cows per ha for weeks 10·20 inclusive in 1968. The fertilizer nitrogen applied (282 kg/ha) was equivalent to a daily rate of 2·02 kg/ha. The feed intake of each cow was measured on three occasions during 1967 and four in 1968.

2. Differences between treatments in outputs per ha were small and on average about 13 000 kg milk and 890 cow grazing days were produced per ha during the 20-week experimental period.

3. Differences between treatments A and B in herbage intake, milk production, milk composition and live-weight change were not statistically significant.

4. When 3·6 kg of a supplementary concentrate was given to some cows, positive responses in milk production, milk composition and live-weight change were found, but the value of the extra milk produced was less than the cost of the concentrate.
The growth of young cattle fed on dried grass alone and with barley 1. Feed intake, digestibility and body gains
Authors: Lonsdale C. R. , Poutiainen E. K. , Tayler J. C.
Published: September 2010

1. The primary growth of a sward of S24 perennial ryegrass was harvested between 23 April and 9 May 1968, artificially dried and either chopped or coarsely milled. The two physical forms of grass were wafered either alone or together with 50% by dry weight of rolled, anaerobically stored barley, and given to 7-month-old, Hereford × British Friesian steers in an experiment of 2 × 2 factorial design.

2. A representative group of animals was slaughtered at the beginning of the experiment, and the remainder were individually fed ad libitum for 70 days, after which they also were slaughtered. During the feeding period digestibility was determined by total faecal collection from all the animals individually on two occasions.

3. Dry-matter intake and live-weight gain were similar on all feeds. The weight of gut contents as a percentage of final live weight was significantly lower and the carcass-weight gain was significantly higher for animals given wafers containing barley compared with those for animals given wafers of grass alone.

4. Coarse milling compared with chopping reduced the apparent digestibility of dry matter, organic matter, cellulose and energy; the addition of barley increased the digestibility of organic matter but further reduced that of cellulose.

5. The efficiency of conversion of digested energy to empty-weight or carcass gain was similar for wafers containing the two forms of forage, but the digested energy of wafers containing barley was converted to carcass weight with significantly greater efficiency than that of wafers consisting solely of grass.

6. Physical separation of the tissues of sample joints failed to show any significant differences in the proportion of fat, muscle and bone as a result of either differences in physical form or the inclusion of barley.

7. The results indicate that live-weight gain is an insufficiently sensitive measurement by which to assess the true productive potential of feeds given to ruminants in short-term experiments.
A note on the consumption of water by the growing pig at several environmental temperatures and levels of feeding
Authors: Mount L. E. , Holmes C. W. , Close W. H. , Morrison S. R. , Start I. B.
Published: September 2010

The voluntary intake of water by 24 groups of 3 to 6 Large White pigs (range of mean body weight: 21 to 73 kg) was measured during a total of 48 periods lasting 3 to 12 weeks each in a large calorimeter equipped as a pig pen. The calorimeter temperature was controlled between 7° and 33°C and the pigs were fed at levels ranging from 42 g feed/kg body weight per day to maximal intake. The mean water: feed ratios were between 2·1 and 2·7 at temperatures between 7° and 22°C, and between 2·8 and 5·0 at 30° and 33°C. The range of mean water consumption extended from 0·092 to 0·184 litre/kg body weight per day.
Effect of level of feed intake on the performance and carcass composition of growing pigs
Authors: Barber R. S. , Braude R. , Mitchell K. G. , Pittman R. J.
Published: September 2010

1. Twelve blocks of six enzootic-pneumonia-free Large White litter-mate pigs were individually fed, wet, from 20 to 92 kg live weight on six different levels of feed intake. Four groups were fed according to scales based on live weight and two were fed on a ‘semi-ad libitum’ system. One of the scales used was based on the ARC (1967) recommendations.

2. Pigs on ‘semi-ad libitum’ feeding grew significantly faster than those on scale feeding although the feed: gain ratios were similar. Differences in performance between the four scale-fed groups were relatively small.

3. Although treatment differences in carcass measurements were in the main small, the commercial grading results favoured the carcasses from the scale-fed pigs. The firmness of backfat assessed by thumb pressure was reduced as the level of feeding was increased.

4. The results were compared with those obtained in a similar trial carried out at Shinfield in 1957 using pigs of a completely different genetic background. The general conclusions reached were similar in the two trials, that to obtain the most satisfactory overall results some form of controlled scale-feeding was necessary.
Utilization of cellulose by pigs and its effects on caecal function
Authors: Farrell D. J. , Johnson K. A.
Published: September 2010

1. Six pigs, four with caecal cannulae, were given diets containing 8% or 26% cellulose. Cannulation did not affect the digestibility of dry matter or cellulose.

2. Digestibility of cellulose, though variable, was higher for the 8%-cellulose diet.

3. Pigs on the 26%-cellulose diet had larger amounts of digesta in the caecum, and lower caecal retention times, than pigs on the 8%-cellulose diet.

4. Measurements of production rates of volatile fatty acids in the caecum indicated that only 2·7% and 1·9% of the apparent digestible energy of the 26%- and 8%-cellulose diets respectively came from the acids, and it was concluded that the caecum played only a small role in the breakdown of feed substances.
Influence of energy and protein concentration in the diet on the performance of growing pigs 4. Effects of sex on response to dietary protein level
Authors: Lodge G. A. , Hardy B. , Lewis D.
Published: September 2010

Two barrows and two gilts from each of 16 litters, by Landrace sires out of Large White × Landrace females, were fed individually one of 4 dietary protein levels (approximately 14%, 17%, 20% and 23% CP) at a common energy level (approximately 3165 kcal/kg DE), from an initial weight of 23 kg to slaughter at 59 kg.

The 17% CP diet gave 19% faster growth and 17% better feed conversion than the 14% CP diet (P < 0·01) with no evident change resulting from further increase in protein level, while the 23% CP diet gave 29% more lean than the 14% CP diet (P< 0·01), as assessed by dis-section of a sample joint.

There were no significant differences between sexes in growth rate, efficiency of feed conversion or carcass composition. Only depth of backfat on the shoulder and at ‘K’ and carcass length showed significant (P < 0·05) sex differences, and the only sex × diet interaction was in eye-muscle area. The results are discussed in relation to those presented in the previous three papers of the series.
A note on mating ability in clun forest ram lambs
Authors: Dýrmundsson Ó. R. , Lees J. L.
Published: September 2010

Some aspects of sexual development and mating behaviour in Clun Forest ram lambs having a wide range of birth dates were studied during two seasons. The 61 ram lambs studied were introduced individually to Clun ewes in oestrus, for short periods at fortnightly intervals during late summer and autumn. Complete matings, i.e. intromission and ejaculation, were first achieved at a mean age of 6 months (range 142–223 days) and a mean body weight of 35 kg (range 24–49 kg). The attainment of physiological puberty preceded the first copulation, often by several weeks. A few individuals had abnormal testes and were partly or completely sterile, but exhibited normal mating behaviour. Early-born lambs tended to complete their first matings at a higher age and heavier body weight than late-born lambs, which suggests a possible seasonal influence on the development of breeding activity in the ram lamb.
A comparison between a rigid rotational grazing system for dairy cows and a system in which grazing alternated with cutting
Authors: Holmes W. , Campling R. C. , Joshi N. D.
Published: September 2010

Two experiments were made with dairy cows in 1969 and 1970 to compare two grazing systems. Treatment A was a rigid rotational system and B was a system in which cows always grazed on an area which had been cut 4 weeks earlier for conservation. For both treatments the stocking rate was 6·2 cow/ha and fertilizer N was applied at a rate equivalent to 2·5 kg/ha per day.

Individual records of milk yield, milk composition and live weight were kept, the quality of herbage available was estimated weekly, and individual intakes were estimated by faecal index methods at approxi- mately monthly intervals. In 1969 the cows remained on the same treatment throughout the season and in 1970 a reversal design was adopted.

The quantities and quality of herbage available per cow were generally similar under both treatments. There were no significant differences in feed intake, or animal production between the treatments. High yields of 11900 kg milk and 28 000 Meal ME per hectare were recorded.
A note on the voluntary intake of Andropogon gayanus hay by cattle, as affected by level of feeding
Authors: Zemmelink G. , Haggar R. J. , Davies J. H.
Published: September 2010

Unchaffed Andropogon gayanus hays, harvested in July, September, early-October, late-October and November, and the July to November regrowth, were offered to White Fulani heifers at three levels of feeding.

Animals on all hays selected for protein and the mean intake of the different hays was closely related to the protein content of the consumed forage. At the low level of feeding all animals, except those on the July hay, left more than 15% residue. Nevertheless, higher levels of feeding had a marked linear effect on feed intake. This effect was largely independent of the effect of level of feeding on the protein content of the consumed ration and was associated with a strong selection for leaves.
Responses to variations in dietary energy intakes by growing pigs 2. The effects on feed conversion efficiency of changes in level of intake above maintenance
Authors: Davies J. L. , Lucas I. A. M.
Published: September 2010

Allowances of about 1·4M, 1·8M, 2·2M, 2·6M, 3·OM, and 3·4M (M = feed required for maintenance) were compared for pigs growing over the live-weight ranges 20·40, 40·60, 60·80, and 80·100 kg, with feed conversion efficiency (FCE) as the main response criterion.

Response to increased digestible energy (DE) allowance was curvilinear; FCE improved rapidly up to 2·2M-2·6M, and changed much less with intakes above 2·6M. It is concluded that optimum FCE occurs at about 2·7M for pigs of 30 kg and at about 3·OM for pigs of 50, 70 and 90 kg.

Allowances of dietary DE suggested by the Agricultural Research Council correspond to 2·56M, 2·95M, 3·04M and 3·08M for pigs of 30, 50, 70 and 90 kg live weight, respectively. It appears that these are near to the optima in promoting the best FCE.

Changes of −25%, −15%, −5%, +5% and +15% in daily intake around the optimum levels caused FCE to deteriorate by averages of about 13%, 4·5%, <1%, <1% and 4·5% respectively. Daily weight gains would then change by about −34%, −18%, −5%, +4% and +10%, respectively.
Stimulation of protein absorption in the newborn piglet's intestine through the use of polyvalent cations
Authors: Smith M. W. , Burton K. A.
Published: September 2010

The transport of protein across the small intestine of the newborn pig was measuredin vitro. The transport of both bovine immune globulin and bovine plasma albumin showed a large variation between piglets. The polycations poly-ornithine, poly-arginine and poly-lysine stimulated both the transport of globulin and albumin. Protamine, histone and arginine were without effect on protein transport. Poly-ornithine became bound to albumin and to the piglet intestinal mucosa. The amount of poly-ornithine needed to stimulate albumin transport was of the same order as that needed to change the electrophoretic mobility of brush border membranes and some 30 times less than that needed to change the charge on the protein. It is concluded that polycations stimulate protein transport by a direct action on the brush border membrane of the pig intestinal mucosa.
Some factors affecting reproducibility in ultrasonic scanning of animals 1. Cattle
Authors: Miles C. A. , Pomeroy R. W. , Harries J. M.
Published: September 2010

Six Hereford and Shorthorn cross steers were ultrasonically scanned in parallel planes perpendicular to the spine. Scanning was performed at the level of each vertebra and extended from the head of the 9th rib to the articulation of the 3rd and 4th lumbar vertebrae. Scans of each live animal were compared with those of its hot carcass and related to dissected sections of the frozen carcass. In general, the difference between an ultrasonic estimate and the carcass measurement was found to depend on the anatomical parameter being investigated, the location on the animal at which measurement was made and the individual interpreting the scan. Results are presented for fat thickness, Mm. longissimi thoracis et lumborum depth, ‘A’, ‘B’ and area measurements. Possible explanations for some discrepancies between the ultrasonic and carcass measurements are discussed.

Additional results showed that whilst judges are consistent within themselves, in general their interpretations of ultrasonic scans differ significantly from each other.
Urine protein levels in the pig
Authors: Wah Loh San , Bourne F. J. , Curtis Jill
Published: September 2010

Sows housed with free access to water were found to have urine protein levels comparable to those recorded for man, dog and sheep. However, in stalled sows with restricted access to water, urine protein levels were twice as high as those of penned sows.

Physiological proteinuria has been found to occur in the piglet, in which respect it is similar to the ruminant and the dog. Proteinuria reaches a peak within 20 hr of birth and lasts for approximately 48 hr. The rapid decline in urine protein levels after this period coincides with gut closure. Proteinuria did not occur in piglets fed on glucose saline, only in those receiving colostrum; however, the continued feeding of colostrum did not prolong the period of proteinuria. In piglets fed varying levels of colostral protein there was a direct correlation between serum protein levels and mean urinary protein concentration during the period of proteinuria, but there was no direct correlation between the amounts of colostral protein ingested and the serum protein level.
The survival of embryos transferred in large groups to sheep of breeds with different ovulation rates
Authors: Land R. B. , Wilmut I.
Published: September 2010

The possibility that embryo survival in a breed of sheep may be related to the number of embryos normally present after natural mating was investigated by transferring large numbers of embryos to sheep of breeds with an approximately two-fold difference in ovulation rate. When the same number of embryos (14) was transferred to each of 12 Scottish Blackface and 11 Finnish Landrace ewes survival was greater in the Finn ewes (10%) than in the Black-faces (4%). The survival of 28% of embryos when transferred in groups of 7 to each of 14 Scottish Blackface ewes indicated that survival was not similar in the two breeds when the number of embryos present was a similar multiple of their natural ovulation rates. When the number of embryos transferred to Scottish Black-face ewes increased from 7 to 14 the decline in survival rate was so great that the number of lambs born also declined, indicating an intermediate optimum ovulation rate for maximum litter size.
Teat orifice stretchability associated with teat diameter gradient and milk yield in lactating cows
Authors: Rathore A. K. , Sheldrake R. F.
Published: September 2010

Teat canal stretchability was measured on 119 lactating cows from two dairy farms, using a probe. Diameter of one hind teat was measured by calipers at the proximal end of the teat and 20 mm above its distal end. Teat canal stretchability, teat diameter at the proximal end and teat diameter gradient were highly correlated with milk yield. Cows with higher teat diameter gradient (i.e., funnel-shaped teats) had higher teat canal stretchability values compared with the cows with lower teat gradient values (i.e., cylindrical teats). Stretchability of the hind teat canal was significantly greater than the stretchability of the fore teat canal.
Open nucleus breeding systems
Authors: James J. W.
Published: September 2010

A theoretical analysis of open nucleus breeding systems, in which there is some introduction of breeding females to the sire breeding nucleus, is presented. Numerical analysis of a discrete generation model shows that the rate of genetic gain may be increased by 10 to 15% by opening the nucleus when selection intensity in females is low. In sheep and beef cattle breeding the optimal structure would be to have about 10% of the population in the nucleus, to get half of the nucleus female replacements from the base population, and to use all nucleus-born females not needed as nucleus replacements for breeding in the base population. The genetic gain, however, is not very sensitive to variation in these parameters. The rate of inbreeding in such an open nucleus would be about half that in a closed nucleus of the same size.
Coordinated trials on the protein requirements of sows 1. A comparison of four levels of dietary protein in gestation and two in lactation
Authors: Greenhalgh J. F. D. , Elsley F. W. H. , Grubb D. A. , Lightfoot A. L. , Saul D. W. , Smith P. , Walker N. , Williams D. , Yeo M. L.
Published: September 2010

1. Gestation diets formulated to contain A, 9; B, 11; C, 13 or D, 15% protein, and lactation diets with C, 13 or E, 17% protein provided eight treatment combinations. They were given at seven centres at 2 kg/day in gestation and approximately 5·7 kg/day in lactation to sows which remained on experiment for three to five parities and produced in total 468 litters. Mean results for parities one to four are given in this summary.

2. For gestation diets A to D mean litter size at birth was 9·7, 10·1, 10·3 and 10·4 live pigs, and at weaning (at 6 weeks), 8·2, 8·7, 8·8 and 8·8. Sows which received lactation diets C and E subsequently produced 10·4 and 10·3 pigs at birth and 8·9 and 8·3 at weaning.

3. Gestation diets had no consistent effects on piglet weights. During lactation, however, diet E gave heavier pigs than C, by 0·2 kg at 3 weeks and 0·5 kg at weaning.

4. Extra protein for either gestation or lactation had a positive effect on sow weight at that stage, but a negative effect in the following stage. There were no direct treatment effects on the time required for re-conception.

5. Twenty experimental sows at the Rowett Institute, together with an additional group given diet A for both gestation and lactation, showed strong positive relationships between lactation protein intake and milk yield or composition.

6. The treatment combination AC (i.e. 9% protein in gestation and 13% in lactation) gave the lowest weight of weaned pigs per litter, and CC gave the highest. The remaining treatments gave similar weights; of these BC (nominally 11 with 13, but actually 11·5 with 13·5% protein) was concluded to provide the lowest protein intake consistent with satisfactory performance.
Litter performance characteristics of pigs in tropical south-western Nigeria 1. Breed differences and effects of some non-genetic sources of variation
Authors: Leigh A. O.
Published: September 2010

Data for 432 litters of pigs were collected from 1965 to 1975 inclusive, at the Fasola Stock Farm, near Oyo in the Western State of Nigeria. The breeds represented were Large White, Duroc and Hampshire, and their crosses. The main objective was to investigate the effects of certain identifiable environmental sources of variation on litter performance characteristics such as litter size, mortality and weight at birth, 3 weeks and 8 weeks of age. Breed and year effects were significant for the litter size traits, but parity of dam, season and breed × season effects were significant only for litter size at birth which increased up to the fifth parity and then declined steadily in subsequent parities. Postnatal pig mortality was affected significantly by breed, litter size at birth and breed × season interaction. It was found that the larger the size of litter at birth the higher the postnatal mortality. Average pig weight at birth was reduced by approximately 0·01 kg for each additional pig in the litter.
The response of early weaned pigs to sub-optimal protein diets supplemented with synthetic lysine
Authors: Campbell R. G.
Published: September 2010

Thirty male piglets weaned at 20 days of age were fed on either a control diet with 20% crude protein containing 1·1 % lysine or one of two diets with 14·6 or 16·6% crude protein. Synthetic lysine was added to the latter two diets at the rate of 0·00, 0·18, 0·36 and 0·54% to provide four diets with 14·6% crude protein and 0·54, 0·72, 0·90 or 1·08% lysine and four diets with 16·6% crude protein and 0·72, 0·90, 1·08 or 1·26% lysine. All diets were offered ad libitum to piglets between 5·5 and 20·0 kg live weight.

Over the live-weight periods 5·5 to 20·0 and 12·0 to 20 kg, live-weight gains and food conversion improved with increasing total lysine to 1·08 % and 0·90 % respectively when pig performance was equal to that achieved on the control diet. The improvement in performance with an increasing level of total lysine during these two periods did not depend on the total protein content of the diet. During the live-weight period 5·5 to 12·0 kg, optimal performance was obtained when pigs were fed on the highest lysine level in the diets with 14·6 and 16·6% crude protein. However, only the diet of 16·6% crude protein promoted pig performance equal to that achieved on the control diet.

Carcass quality did not respond to lysine supplementation independently of protein level. With thedietof 14·6% crude protein, optimal carcass quality was obtained with 0·90 % lysine but was significantly poorer than that for the control. With the diet of 16·6% crude protein, carcass quality improved over the entire range of lysine supplementation and with 1·26% lysine was superior to that for the control.
The effects of plane of nutrition, live weight, temporary weaning and breed on the occurrence of oestrus in beef cows during the post-partum period
Authors: Holness D. H. , Hopley J. D. H. , Hale D. H.
Published: September 2010

The occurrence of oestrus and ovarian function during the post-partum period was examined in 160 lactating beef cows of the Africander and Mashona breeds. Cows were fed either to gain 12 to 14% (High) or to lose 12 to 14% (Low) of their autumn peak live weight (early pregnancy) by mid-breeding season. Half the cows in each group were subjected to an increase (Low-High) or decrease (High-Low) in nutrient intake for a 25-day period starting at 25 days partum. Nursing was interrupted for an 8-day period in half of the cows at 50 days post partum by the application of nose plates to their calves.

Oestrus occurred significantly earlier in the high than the low plane cows (66 v. 75 days post partum respectively, P< 0·05), but short-term fluctuations in nutrient supply had no apparent effect on the incidence of oestrus. Temporary weaning significantly reduced the mean time from calving to first oestrus in the high-plane (P< 0·01) but not in the low-plane cows, and in Mashona (P<0·05) but not in Africander cows. There was a lower incidence of ‘silent’ oestrus and the mean occurrence of oestrus was significantly earlier (P< 0·001) in the Mashona when compared with the Africander cows.
Fertility in Cheviot ewes. 1. The effect of body condition at mating on ovulation rate and early embryo mortality in North and South Country Cheviot ewes
Authors: Gunn R. G. , Doney J. M.
Published: September 2010

In two experiments over 2 years, 113 North Country Cheviot and 132 South Country Cheviot hill ewes were differentially group-fed over a 10-week period to achieve either good or moderate body con- dition. Ewes were maintained in these levels of condition over the 5 weeks prior to mating. After mating, ewes were killed either on return to service or between days 23 and 85 for counts of corpora lutea and viable embryos.

Ovulation rate in each breed was positively related to body condition at mating. Embryo mortality, as ova loss, was not influenced overall by breed, type of ovulation, year of recording, or body condition. Although comparisons of loss were partly confounded by a differen- tial distribution in the number of ova shed in each breed and body condition group, there was an apparent breed difference in loss of single- and multiple-shed ova. Potential lambing rate therefore showed greater response to improved body condition at mating in the North Country Cheviot breed than it did in the South Country Cheviot.