bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth hormone pulsatility in ram lambs of genotypes selected for fatness or leanness
Authors: Suttie J. M. , Veenvliet B. A. , Littlejohn R. P. , Gluckman P. D. , Corson I. D. , Fennessy P. F.
Published: September 2010

Although it is known that growth hormone (GH) influences body composition in ruminants, the precise role of the pattern of GH secretion is not known. We have studied the pulsatile release of GH and insulin-like growth factor 1 (IGF 1) secretion in the male progeny of rams from lines selected either for {fat genotype) or against (lean genotype) fatness. Seventy-two lambs (36 each of the fat and lean genotype) were kept on high-quality pasture and randomly allocated within genotype to treatment at 2, 3, 3·5, 4,5 or 6 months of age. The procedure, which was identical for each sampling period, was to sample each lamb through a jugular cannula every 10 min for 6 h, and then, following an overnight fast, to slaughter and analyse the carcass for fat. All blood samples were analysed for GH and samples taken each hour for total plasma IGF 1. The GH data were further analysed with the pulse detection routine PULSAR. Carcass fatness, adjusted for cold carcass weight, was greater for fat genotype animals than for the lean genotype. GH was pulsatile in all profiles but the pattern differed with time and genotype. Mean GH and pulse amplitude decreased with time but did not differ between genotype, although the lean genotype had higher mean GH at five of the six sampling periods. In contrast, GH pulse frequency and IGF 1 were significantly higher for the fat compared with the lean genotype lambs. GH mean and amplitude correlated negatively with carcass fatness in both genotypes and GH pulse frequency and total IGF 1 correlated positively with fatness for the lean genotype only. When carcass weight and genotype were fitted to these relationships, GH mean and total IGF 1 were found to have independent negative and positive effects, respectively, on carcass fatness. Because GH mean had a separate effect on fatness independent of genotype or cold carcass weight, it is likely that GH secretion influences composition by the same basic mechanism in both genotypes. However, although the slopes of these relationships did not differ significantly between the genotypes, the intercepts were significantly different indicating that over and above the basic mechanism, at any level of GH, the lean genotype lambs were leaner than the fat genotype lambs. This may indicate a measure ofGH resistance in the fat genotype lambs.
Environmental parameters necessary to define comfort for pigs, cattle and sheep in livestock transporters
Authors: Randall J. M.
Published: September 2010

Most livestock are transported at least once during their lifetime. Environmental conditions inside the transporter are critically dependent on many factors which can be controlled by well designed and carefully operated ventilation systems. Heat, moisture and carbon dioxide production of cattle, pigs and sheep are fitted to simple models as bases for ventilation design criteria. These assume that the animals are not well fed immediately before or during transport and that maintenance metabolic heat production applies. Interactions between temperature and humidity during transport are important at temperatures above 24°C.

Ventilation slots along the sides of transporters can be occluded by the bodies of the stock themselves. Relevant dimensions of pigs, cattle and sheep related to body weight are provided as additional design parameters. Stocking density interacts critically with other aspects of transport and normally recommended values are shown to be inconsistent. Space requirements should be based on species and body weight, provided that the ventilation capacity is satisfactory.

Proposed European regulations on the transport of livestock provide general guidelines for the provision of ventilation, but no means of achieving these requirements. This paper draws together detailed criteria for establishing acceptable space, thermal, psychrometric and gaseous conditions on transporters for pigs, cattle and sheep. Application of these quantitative criteria will assist shippers and regulating authorities in providing more suitable environmental conditions than are frequently achieved at present.
Effect of dam nutrition and suckling on lactation in Borana cows and growth in their Borana × Friesian crossbred calves in an early weaning system in Ethiopia
Authors: Tegegne A. , Osuji P. O. , Lahlou-Kassi A. , Mukasa-Mugerwa E.
Published: September 2010

Forty-four Borana × Friesian F1 crossbred calves born to Borana (Bos indicus) cows were randomly assigned to either suck their dams hvice daily or bucket-feeding with 1341 milk over a 57-day pre-weaning period. Their dams were also allocated either to a supplement group with grass hayad libitumand 5 kg per head per day of a concentrate ration or to an unsupplemented group withad libitumgrass hay only. Calves were fed in individual boxes in a calf house. The mean birth weight of calves was 24·8 (s.e. 1·8) kg. Suckled calves were heavier (P < 0·01) at weaning (47·7 (s.e. 1·9) v.37·1 (s.e. 1·8) kg) and had faster pre-weaning growth rate (411 (s.e. 30)v.215 (s.e. 29) g/day) than bucket-fed calves. Calves which sucked supplemented cows were heavier (P < 0·001) at weaning (51·2 (s.e. 2·6)v. 44·2 (s.e. 2·6) kg), had faster (P < 0·01) pre-weaning growth rate (477 (s.e. 41)v.346 (s.e. 41) glday) and higher (P<0·01) daily milk intake (2·6 (s.e. 0·2)v.1·6 (s.e. 0·2) I/day) than those which sucked unsupplemented cows. Mean concentrate intake was 302 (s.e. 30) g/day for bucket-fed calves and 341 (s.e. 33) and 408 (s.e. 33) g/day for calves which sucked supplemented and unsupplemented cows. Cow milk production was higher (P < 0·01) in suckled than in milked cows (3·3 (s.e. 0·2)v.1·0 (s.e. 0·2) I/day) and in supplemented than unsupplemented cows (3·9 (s.e. 0·2)v.2·7 (s.e. 0·2) I/day). Concentrations of milk protein, fat and total solids averaged 39 (s.e. 15), 49 (s.e. 16) and 143 (s.e. 21) g/kg, respectively and were not significantly influenced by either concentrate supplementation or suckling. Restricted suckling and early weaning coupled with appropriate calf and cow feeding regimes could be one of the alternatives for calf rearing under smallholder and small scale peri-urban dairy production systems. However, further studies are warranted to evaluate the effects of such a strategy on both calf and cow performances under these production systems.
Effect of whole cottonseed on energy partitioning and nitrogen balance in sheep
Authors: Arieli A.
Published: September 2010

Energy and nitrogen balance partitioning was studied in sheep given whole cottonseed (WCS), vetch hay and commercial concentrates. Sheep were offered diets containing 0 (CON) and 250 g/kg WCS at maintenance (LF) and twice maintenance (HF) levels. Digested energy, metabolizable energy (ME) and heat production (HP) were measured in a balance trial combined with indirect calorimetry. Dietary ingredients were also incubated in sacco in sheep rumens. Feeding WCS resulted in decreased energy digestibility at HF (0·718 v. 0·751) but not at LF. Loss of energy as methane expressed as a proportion of gross energy intake for CON and WCS respectively was 0·078 and 0·057 at LF and 0·061 and 0·051 at HF. In both diets, HP was similar at LF. In contrast HP amounted to 0·657 of the ME for CON and only 0·61 for WCS at HF.

Apparent nitrogen digestibility was not affected by WCS consumption. Urinary nitrogen was similar for both diets at LF, but at HF it was higher in the WCS diet. Thus at HF, retained nitrogen was 045 and 0·12 of apparently digested nitrogen for CON and WCS respectively.

Ruminal degradation of organic matter was proportionately 0·87 and 0·77 of apparent digested organic matter in the total tract for the CON diet, at LF and HF respectively and 0·80 and 0·73 for the WCS diet, at LF and HF respectively. In the four groups ruminal nitrogen degradation was equal to apparent whole-tract nitrogen digestion. It was concluded that feeding WCS may decrease metabolic HP in ruminants. Utilization of WCS could be improved by taking measures to decrease urinary nitrogen losses.
The economic performance of dairy cows of different predicted genetic merit for milk solids production
Authors: Simm G. , Veerkamp R. F. , Persaud P.
Published: September 2010

The aim of this study was to examine the relationship between pedigree index for kg fat plus protein and the financial margins between milk returns and food, health and reproduction costs in individual lactations. Records of milk and milk component production, food intake, health and reproduction were obtained for individual Holstein-Friesian cows over 38 weeks of lactation over a 7-year period, at the University of Edinburgh/Scottish Agricultural College Langhill dairy cattle research centre. Records for a total of 302 lactations were collected. Milk prices, input costs and margins were calculated for individual animals, using 1989/90 values. Regressions of margin over food costs (MF) and margin over food, health and reproduction costs (MFHR) on pedigree index (PI) for kg fat plus protein were all positive and ranged from £2·50± 3·00 per kg PI for MFHR for heifers, to £6·50 ± 2·10 per kg PI for MFHR for all animals. The lower regression for heifers was attributed to higher reproduction costs in animals of higher genetic merit, though the standard error for the regression estimated in this smaller data set was high. Sensitivity analyses showed that the regression coefficients remained very similar, even with ±50% changes in food, health or reproduction costs. It was concluded that selection on PI for kg fat plus protein is likely to lead to increased margin over food, health and reproduction costs.
The behavioural, endocrine and immune responses of sheep to isolation
Authors: Cockram M. S. , Ranson M. , Imlah P. , Goddard P. J. , Burrells C. , Harkiss G. D.
Published: September 2010

Two groups of five sheep (7 months of age) were moved and isolated in pens which did not allow visual and tactile contact with other sheep for 24 h. They were then moved back to their original pens where visual and tactile contact was possible. After 24 h the procedure was repeated seven times for one group (group 8-1) and thirteen times for the other group (group 14-1). One group (control) of five sheep remained in pens where visual and tactile contact was possible. When isolated the lambs spent more time standing still in an alert posture, less time eating and resting, and vocalized more than control lambs. The heart rate of the lambs increased when they were moved between pens and during isolation. The plasma concentration of cortisol was significantly increased after 1·5 h and 3 h of isolation. The plasma concentration of prolactin was increased after 1·5 h of isolation. After 3 h of isolation the number of neutrophils in the blood was increased and the numbers of T-lymphocytes (CD2), T-helper-lymphocytes (CD4) and yd-lymphocytes (T19) were decreased. After 24 h of isolation the lymphocyte blastogenic response to Con A was lower and the numbers of T-lymphocytes and T-helper-lymphocytes were still less than those in control lambs. Although there were still behavioural changes when the lambs were isolated for the seventh time, no cortisol, prolactin and leucocyte changes were found. These results suggest that stressors similar to isolation, which can occur during normal management practice, may elicit short-term leucocyte changes in lambs.
Milk production from grass silage diets: effects of silage characteristics and the amount of supplementary concentrate
Authors: Aston K. , Thomas C. , Daley S. R. , Sutton J. D. , Dhanoa M. S.
Published: September 2010

High digestibility ryegrass was ensiled using either good methods including formic acid application (HDG) or poor methods without formic acid (HDP). Low digestibility ryegrass (LDG) and lucerne (LUC) were ensiled using similar methods to HDG. Digestible organic matter in the dry matter (DM) in vivo (DOMD) for HDG, HDP, LDG and LUC were 0·756, 0·774, 0·645 and 0·562 respectively. Silages were offered ad libitum to 40 HolsteinFriesian cows in two Latin-square design experiments during weeks 8 to 22 of lactation either alone (experiment 1) or with 3, 6, 9 or 12 kg concentrate DM per day (experiment 2). Relative intakes of silage given alone were respectively 1·00, 0·44, 0·98 and 0·79. Low intake of HDP could not be predicted from silage analysis. In experiment 2, DM intake increased by 0·11 kg and milk yield by 0·24 kg for each 0·010 change in grass silage DOMD. Intake of HDG, LDG and LUC declined linearly with increasing concentrate, on HDP the effect was non-linear and intake increased up to the 6 kg level.

In experiment 1, milk and protein yields were greatest on HDG, protein yield was higher on LDG than LUC and fat concentration higher on HDP and LUC. With supplementation milk yield was greatest on HDG up to the 6 kg level, at higher levels differences between silages were not significant. Fat concentration was highest on LDG and protein highest on HDG and lowest on LUC. On all silages giving the highest concentrate level reduced the concentration and yield of fat. Protein concentration increased up to the 9 kg level. Fat plus protein yields reached a maximum on HDG with 6 kg concentrate DM per day and with 9 kg on the remaining silages.
Parasitism and production in farm animals
Authors: Sykes A. R.
Published: September 2010

The impact of internal and external parasitism on productivity of farm animals is considered for cattle, sheep, pigs and poultry. The parasitic challenge experienced and the outcome of that challenge is a dynamic one in which environment, management practices, including housing or grazing management, nutritional status, the host's ability to develop effective immunity and the speed with which this can occur, play a significant role. Much of our assessment of the impact of infection comes from pathophysiological and nutritional studies with contrived infestations. A common feature of all infestations is reduced efficiency of food utilization through reduction in food intake, though in some cases increases in nutrient requirement are induced as a result of damage to or loss of host tissue. Assessment of the impact on productivity in the field is technically very difficult and must take account of fluctuating challenge, determined by environmental and management decisions, and the manager's objectives for the performance of a particular category of livestock. This review attempts to integrate the assessment of losses in productivity based on pathophysiological studies with those based on protection of groups of livestock in production systems by regular pesticide use. Throughout the review the limitations inherent in both approaches and in our knowledge of how parasites impair productivity of the host are emphasised.
Relationship of diet, hoof type and locomotion score with lesions of the sole and white line in dairy cattle
Authors: Logue D. N. , Offer J. E. , Hyslop J. J.
Published: September 2010

Three groups of 16 cattle each comprising three multiparous Jersey cross Holstein-Friesian cows, seven primiparous and six multiparous Holstein-Friesian cattle were offered, ad libitum, a silage-based complete diet with different concentrate ingredients following an initial 3-week covariate period. The relationship between these three diets and other parameters with lesions of the weight-bearing surface of the hoof was studied by scoring mobility weekly (locomotion score) and examining all the feet of all cows for visual lesions particularly those involving the horn of the foot. In addition hoof angle, hardness and growth and wear were also recorded. The mean locomotion score during the initial 3-week covariate period was a significant covariate for the subsequent locomotion score, milk yield, and live weight (P< 0·001). Furthermore weekly locomotion score also proved a significant covariate for weekly milk yield (P< 0·05). There were no significant differences between dietary treatment groups for locomotion score, overall lesion score (despite significantly fewer ulcers of the sole in one dietary group:P< 0·001) but a significant (P< 0·05) difference between cow ‘type’ and there was also a significant (P< 0·05) diet × breed interaction for locomotion score and milk yield. It was concluded first that initial mobility was an important factor in subsequent mobility of the cow and so experimental design; secondly that while nutrition and genotype interacted to influence mobility, visual lesions of the hoof and lameness, the mechanisms involved were far from clear; and thirdly that the simple lesion score used required some adjustment or correction factor(s) to ensure that more severe lesions were given a greater weight than a simple unitary increase.
Genetic and phenotypic correlations between linear type traits and production traits in Holstein-Friesian dairy cattle
Authors: Brotherstone S.
Published: September 2010

First lactation production and linear type records of 72 559Holstein-Friesian cows, calving from 1982 to 1989, were analysed by multivariate restricted maximum likelihood, using a sire model. The data comprised offspring of 1066 randomly used sires, and 91 proven i.e. widely used bulls. All phenotypic correlations between the type traits and the yield traits were small, but moderate genetic correlations were obtained between milk, fat and protein yield and angularity (~—0·43) and between the yield traits and udder depth (~0·44), indicating that higher yielding heifers are more angular and have deeper udders. The heritabilities of the type traits were in line with previous analyses, but those for milk, fat and protein yield were rather high at 0·47, 0·52 and 0·45 respectively
Selection for components of efficient lean growth rate in pigs 2. Selection pressure applied and direct responses in a Landrace herd
Authors: Cameron N. D. , Curran M. K.
Published: September 2010

Responses to divergent selection for lean growth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Landrace pigs were studied. Selection was practised for four generations with a generation interval ofl year. A total of 2642 pigs were performance tested in the high, low and control lines, with an average of 37 boars and 39 gilts performance tested per selection line in each generation. The average within-line inbreeding coefficient at generation four was equal to 0·04. There was one control line for the DFI and LFC selection groups and another control line for the LGA selection group. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively with ad-libitum feeding. The selection criteria had phenotypic s.d. of 32, 29 and 274 units, for LGA, LFC and DFI, respectively, and results are presented in phenotypic s.d.

Cumulative selection differentials (CSD) were 5·1, 4·5 and 5·5 phenotypic s.d. for LGA, LFC and DFI, respectively. Direct responses to selection were 1·4,1·1 and 0·9 (s.e. 0·20) for LGA, LFC and DFI. In each of the three selection groups, the CSD and direct responses to selection were symmetric about the control lines. The correlated response in LFC (1·1, s.e. 0·19) with selection on LGA was equal to the direct response in LFC. In contrast, the direct response in LGA was greater than the correlated response (0·7, s.e. 0·18) with selection on LFC. There was a negative correlated response in DFI (-0·6, s.e. 0·18) with selection on LFC, but the response with selection on LGA was not significant (0·2, s.e. 0·16).

Heritabilities for LGA, LFC and DFI ivere 0·25, 0·25 and 0·18 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·12 (s.e. 0·02). Genetic correlations for LFC with LGA and DFI were respectively positive (0·87, s.e. 0·02) and negative (-0·36, s.e. 0·09), while the genetic correlation between DFI and LGA was not statistically different from zero, 0·13 (s.e. 0·10). Selection on components of efficient lean growth has identified LGA as an effective selection objective for improving both LGA and LFC, without a reduction in DFI.
A note on a simple criterion for choosing among sample joints for use in double sampling
Authors: Cook G. L. , Jones D. W. , Kempster A. J.
Published: September 2010

A simple criterion is described for selecting which of a number of sample joints estimates most precisely for a given cost (T) the mean lean percentage of a population of carcasses, using double sampling. It is shown that the best joint is the one giving the largest value of:

where ρ is the correlation between the lean content of the sample joint and the lean content of a carcass side (y), and k is the cost of the sample joint dissection as a proportion of the cost of side dissection. The optimum proportion of carcasses to side dissect is:

and the standard error of the estimated mean is then:

where σyis the standard deviation of y and C is the cost of measuring y.
The voluntary intake and digestibility by cattle and sheep of dried grass wafers containing particles of different size
Authors: Wilkins R. J. , Lonsdale C. R. , Tetlow R. M. , Forrest T. J.
Published: September 2010

Wafers of dried grass which differed in particle size (modulus of fineness) were prepared and fed ad libitum to cattle and sheep. The response of the two classes of stock to the feeds was similar. The digestibility of organic matter and of cellulose decreased with decrease in modulus of fineness (more fine particles) and this was associated with more rapid passage of the finely-milled material through the alimentary tract. Organic matter intake generally increased with decrease in modulus of fineness, but the pattern of response differed between experiments. In one experiment the difference in voluntary intake between feeds with modulus of fineness of 2·5 and 1·0 was less than 5% and not significant, but in a second experiment the intake of feed with modulus of fineness of 2·1 was 18% lower than that of feed with modulus of fineness of 1·0. In the first experiment the wafers broke down during handling and feeding with the result that the feed of low modulus of fineness was extremely dusty, but in the second experiment a binding agent was included and little breakdown of wafers occurred. It is suggested that dustiness may have restricted the intake of some of the feeds in the first experiment. Intakes of digestible organic matter did not differ significantly between treatments in either experiment.
Photoperiodism in the ewe 5. An attempt to induce sheep of three breeds to lamb every eight months by artificial daylength changes in a non-light-proofed building
Authors: Ducker M. J. , Bowman J. C.
Published: September 2010

An attempt to induce ewes to lamb at intervals of 8 months using high levels of artificial daylength applied in a non-light-proofed building was carried out over a period of 2½ years.

Thirty each of Dorset Horn, Clun Forest and Kerry Hill ewes were used. There were two different light regimes, both involving abrupt changes in daylength, all of which occurred at daylengths in excess of natural daylength. In both treatments the artificial daylength was abruptly increased to 22 hr at conception. In one treatment there was an abrupt decrease in daylength at parturition whilst the other treatment was an abrupt decrease in daylength approximately 50 days before parturition. The size of the daylength decrease possible was determined by the natural daylength at the time the decrease was applied and at the estimated time of onset of next oestrus.

The majority of ewes lambed four times in the 2½ year period, parturition occurring in March-April 1969, December 1969-January 1970, September-October 1970 and May 1971. The Clun Forest ewes produced 38, 29, 20 and 22 lambs at the four lambings, whilst the Dorset Horn ewes produced 41, 35, 26 and 25 lambs at the four lambings. Only 11 of the Kerry Hill ewes lambed throughout the whole experiment producing 3, 5,0 and 7 lambs at the four lambings. It is suggested that the changes in daylength at these high levels controlled the breeding activity of the ewes.
An evaluation of beef carcass quality 2. Influence of variation in grazing intensity and the level of barley supplementation with silage on the carcass and meat quality of Friesian steers
Authors: Hinks C. E. , Prescott J. H. D.
Published: September 2010

Two experiments concerning the effects, on the carcass and meat characteristics of 18-months-old Friesian steers, of variation in grazing intensity and the level of barley feeding with silage are reported.

Groups of 12 steers were grazed at different intensities over 5-month grazing periods, such that live-weight differences of 38 kg and 16 kg were recorded at housing. No compensatory growth was recorded during the subsequent winter feeding period.

Whilst the grazing treatments had little effect on carcass or meat quality, higher levels of barley feeding with silage over the winter period (710v.410 kg/steer) had significant effects on live-weight gain, and increased carcass weight by 21 kg at slaughter. The higher yield of carcass weight was reflected in significant differences in carcass composition, joint proportions and retail cut-out value. Sixty per cent of the carcass weight difference was removed as trim fat. Differences in carcass fatness were not associated with any differences in eating quality.
Milking ability in relation to size and shape of teats
Authors: Ovesen E.
Published: September 2010

Length and diameter of teats were measured on first-lactation cows at Danish progeny testing stations. The cows were also classified into four groups according to shape of teat and teat tip. All traits were corrected for yield level and interval after calving and correlated with milking characteristics. The conclusions drawn were:

1. Teat length influences both average rate of milk flow and yield on hand stripping. The most satisfactory milking is obtained in cows with short teats. In Red Danish, Black and White Danish and Jersey cows, respectively, desirable length of fore teat is ≤ 6, ≤ 6, and ≤ 5 cm, and of rear teat about 1 cm shorter.

2. Teat diameter is of no significant importance to average rate of milk flow, but yield on hand stripping is most satisfactory when the diameter is ≤ 2·4 cm.

3. Teat shape must be very extreme before an adverse influence is recorded on average rate of milk flow and yield on hand stripping.

4. The milking characteristics of cows are correlated with shape of the teat tip. The highest rate of milk flow and the lowest yield on hand stripping is found in cows with flat and concave teat tips.

5. A relationship exists between teat length and the shape of the teat tip, and partial correlation coefficients show that of the teat traits investigated the most important factor affecting average rate of milk flow is the shape of the teat tip whilst teat length—similar to the effect of teat diameter—is of greater importance to the yield on hand stripping. Investigations into the possible consequences for udder health must, however, be conducted before selection for a special shape of the teat tips is introduced.
Seasonal variation in oestrus and ovarian activity of Finnish Landrace, Tasmanian Merino and Scottish Blackface ewes
Authors: Wheeler A. G. , Land R. B.
Published: September 2010

The patterns of seasonal variation in reproductive activity were observed over a period of 15 mo for approximately 15 females of each of three breeds: Finnish Landrace (Finn), Tasmanian Merino (Merino) and Scottish Blackface (Blackface). The incidence of oestrus was measured by teasing with vasectomized rams, and the incidence and rate of ovulation were determined frequently by laparoscopy. Luteal function was assessed from peripheral venous blood progesterone concentration on days 7 and 11 of the oestrous cycle. Nutritional status was monitored by recording body weight and plasma-free fatty acid levels throughout the study.

The breeding seasons differed significantly: Finn, October to May; Merino, September to February; and Blackface, October to February. Variation in the incidence of ovulation was similar to that in the incidence of oestrus for each breed. The incidence of silent ovulation varied with the breed, being greatest in the Merino and least in the Finn. The ovulation rate varied among breeds (Finn, 2·99; Merino, 1·08 and Blackface, 1·30), and during the breeding season (e.g. Finn: November, 3·5; March, 2·6). Follicles were observed in each breed throughout the period of study.

The pattern of variation in progesterone concentration was similar for each breed despite their different breeding seasons. In addition to breed differences in ovulation rate and in onset and end of the breeding season, the sensitivity to oestrogen was apparently such that, with the Finn if oestrogen secretion was high enough to stimulate ovulation it would usually also stimulate oestrus, whereas with the Merino ovulation often occurred without oestrus; this suggests that in the Merino the centres controlling ovulation are more sensitive to oestrogen than those controlling behaviour.
The effect of concentrate, barley and dried grass on the voluntary intake of different silages
Authors: McIlmoyle W. A. , Murdoch J. C.
Published: September 2010

In two experiments with steers (initial live weight 339 kg) the effect of dried grass, barley and concentrates on the intake of ‘wilted’ and unwilted grass and whole-crop barley silage was investigated.

In both experiments there was no significant effect of silage type on silage dry-matter intake when given alone or with a supplement. In Experiment 1, supplementation significantly reduced (P<0·05) the intake of silage dry matter (DM) from unwilted and whole-crop barley silage. Total DM intake was significantly higher (P<0·05) for the ‘wilted’ silage diet than for either the unwilted or whole-crop barley silage diets. In Experiment 2, supplementation had no significant effect on total DM intake. Digestible energy intake was significantly higher (P < 0·05) from whole-crop barley silage supplemented with concentrate rather than barley or dried grass and was significantly lower (P<0·05) from unwilted silage diets (P<0·05) when dried grass rather than concentrate or barley was given. In the second experiment, ration digestibility and rate of passage of digesta results are reported.
The effect of milk intake on the intake of cut and grazed herbage by lambs
Authors: Penning P. D. , Gibb M. J.
Published: September 2010

Fifty-three lambs were artificially reared from 1 day old. From 14 days of age they were either housed and offered cut herbage or grazed at pasture.

Five milk feeding treatments were allocated to both the housed and the grazing lambs; these were a total of 50, 70, 90 and 110 kg of ewes' milk given over 12 weeks and milk substitute for 4 weeks. Three additional lambs were housed and offered milk ad libitum.

Digestibilities of the dietary components, herbage and milk intakes and lamb growth rates were measured.

Similar digestibility coefficients were obtained for milk and for herbage when consumed together compared with individually.

Milk intake was negatively correlated with herbage intake and positively correlated with growth rate.

Under conditions permitting ad libitum intake, lambs at pasture had higher intakes of herbage than lambs offered cut herbage indoors. Equations are given which enable herbage intake at a particular age to be predicted from total milk intake.
A model of nutrient utilization and body composition in beef cattle
Authors: France J. , Gill M. , Thornley J. H. M. , England P.
Published: September 2010

A simple dynamic model of metabolism in growing beef cattle is described; the scheme is based on carbon and nitrogen fluxes. There are six state variables, three relating to blood metabolite levels and three to body composition. The blood metabolite variables are acetyl-coenzyme A equivalents, glucose equivalents and amino acids, and the body composition ones are ash, lipid and protein. The fluxes in the model are based on nine biochemical transactions, six of which are catabolic and three biosynthetic. The model simulates changes in carcass composition in response to changing nutrient input and gives a measure of agreement with comparative slaughter data. It also highlights the need for more complete data on profiles of nutrient absorption in association with comparative slaughter experiments.
The voluntary hay intake by ewes during the first weeks of lactation
Authors: Bocouier F. , Thériez M. , Brelurut A.
Published: September 2010

In eight experiments, ewes nursing one or two lambs were offered restricted amounts of concentrate in the range 285 to 605 g dry matter (DM) per day and hay ad libitum, from lambing until day 42 of lactation.

Hay intake increased sharply during the first 2 weeks and reached its maximum during the 5th or the 6th week. Ewes' body weight at lambing, ewes' body-weight change, and milk production (estimated by litter growth rate) were significantly related to hay intake which depended also on breed (Romanov × Limousine ewes eating more than pure Limousine, P < 0·001) and age (mature ewes eating more than old ewes, P < 0·001) but not on number of suckled lambs.

Replacement rate of concentrates for forage increased as lactation progressed (0·53 to 0·86 from first to third fortnight) and varied with hay neutral detergent fibre (NDF) concentration (0·42 or 0·89 for hays with 700 or 500 g NDF per kg DM). Daily hay DM intake decreased by 1·28 g for each gram of hay NDF content increment. The NDF effect was increasingly more important as lactation progressed.

Utilization of present results in formulating diets for lactating ewes is discussed.
Production responses of New Zealand Friesian cows at pasture to exogenous recombinantly derived bovine somatotropin
Authors: Hoogendoorn C. J. , McCutcheon S. N. , Lynch G. A. , Wickham B. W. , MacGibbon A. K. H.
Published: September 2010

Recombinantly derived bovine somatotropin (bST) was administered to 25 Friesian cows by 2-weekly injections of a controlled release formulation at a dose rate equivalent to 25 mg/day. Treatment commenced 7 to 11 weeks after calving and continued for 26 weeks. A comparable group of 25 cows treated only with the slow release vehicle served as a control. During the treatment period, administration of bST increased yields of milk (controls 2358 v. bST 2598 (pooled s.e. = 39·8) kg; P < 0·01), fat (107·4 v. 119·3 (pooled s.e. = 1·9) kg; (P < 0·01) and protein (84·7 v. 93·7 (pooled s.e. = 1·2) kg; (P < 0·001). Magnitude of the treatment effect was strongly influenced by season, being greatest in spring/early summer (weeks 1 to 13 of treatment) and autumn (weeks 19 to 25) but not significant during the intervening summer dry period when herbage yield was low. Voluntary intakes, as measured by indigestible marker techniques at weeks 7 to 8 and 12 to 13 of treatment, were not influenced by bST administration. However, the net loss of body condition experienced by bST-treated cows (0·3 condition score units) was not sufficient to explain their responses in yield of milk and milk components, suggesting that some responses in voluntary intake had occurred. Administration of bST had little effect on milk composition, fatty acid composition of milk fat, live weight, reproductive performance or milk yield in the subsequent lactation.
Influence of shearing regime and grass silage quality on the performance of pregnant ewes
Authors: Black Heather J. , Chestnut D. M. B.
Published: September 2010

The performance of housed ewes, shorn at various stages during pregnancy and offered silages ad libitum made from grass harvested at two contrasting stages of growth, was studied. The mean increase in silage dry matter (DM) intake due to shearing (0·11 kg/day; P > 0·05) was small in comparison with that resulting from offered earlier-cut silage (0·27 kg/day; P < 0·001). The mean increase in twin lamb birth weight from ewes shorn at least 6 weeks before lambing was almost 1 kg per lamb (P < 0·01) with no significant effect on ewe live-weight change. Greatest increase in lamb birth weight (1·11 kg; P < 0·01) was produced by shearing several times during pregnancy, with least response (0·23 kg; P < 0·05) from shearing once only, 4 weeks before lambing. The effect of silage quality on lamb birth weight was not significant, despite the large difference in DM intake of the two silages. This difference in intake was reflected by ewe live-weight change over pregnancy with those ewes offered early-cut silage gaining 5·57 kg while those offered late-cut silage lost 4·53 kg (P < 0·001). There was a marked fall in respiration rate and rectal temperature after each shearing and, compared with shorn ewes, unshorn ewes had a mean gestation length which was 2·04 days shorter (P < 0·01). In terms of lamb growth rates, ewe milk yields and milk composition, the performance on all treatments after turn-out to pasture was satisfactory and no significant carry-over effect of treatments applied during pregnancy were observed during the first 5 weeks of lactation.
The impact of different genetic models on the optimum design of crossbreeding experiments
Authors: Sölkner J.
Published: September 2010

A method for the iterative set-up of optimum designs for crossbreeding experiments was used to study the robustness of designs to differences in the biological interpretation of two-locus epistatic interaction. Designs could be found which are efficient for the estimation of genetic models including, alternatively, seven different types of epistatic effects. Also, the design efficiency of a large-scale beef cattle crossbreeding experiment between Angus and Hereford cattle conducted at the Clay Center, Nebraska, and reported by Koch, Dickerson, Cundiff and Gregory (1985) was investigated and found to be high (proportionately 0·88 of the optimum). It was concluded that choice of the right genetic groups (i.e. types of crossbreds) seems to be more important for a good design than the exact number of observations allocated to each group.
Growth characteristics and carcass composition of pigs with known genotypes for stress susceptibility over a weight range of 70 to 120 Kg
Authors: Aalhus J. L. , Jones S. D. M. , Robertson W. M. , Tong A. K. W. , Sather A. P.
Published: September 2010

A total of 805 Lacombe pigs of different genotype with respect to halothane sensitivity (halothane positive, nn = 205; heterozygote, Nn = 214; halothane negative, NN = 386) were slaughtered over a range in live weight (70 to 120 kg) to assess tissue growth patterns using the allometric equation (y = aXh). The nn genotype was older at slaughter than the NN genotype, but pigs from each genotype were killed over a similar weight range. The relative growth of the primal cuts was influenced by genotype, with nn pigs having a lower coefficient for the bottom shoulder (picnic) and a higher coefficient for the belly. The relative growth of bone was similar for genotypes (P > 0·05) but the relative growth of lean was lower and the relative growth of total fat and depot fat (subcutaneous and intermuscular) was higher for the nn genotype compared with the Nn and NN genotypes. On a within-tissue basis, the relative growth of the tissues in each primal was similar, except for the ham, where the relative growth of lean was higher for nn pigs compared with the two other genotypes. Small differences in tissue distribution were evident, but seldom exceeded 30 g/kg. Although nn pigs had a higher lean content and higher lean: bone ratio than Nn or NN pigs at similar live weights, their relative advantage in composition decreased with increasing live weight.
Analysis of some factors which affect the productivity of beef cows and of their calves in a marginal rainfall area of Rhodesia 2. The yield and composition of milk of suckling cows
Authors: Richardson F. D. , Oliver J. , Clarke G. P. Y.
Published: September 2010

The milk production of three groups of cows grazing on veld and receiving different amounts of concentrates during winter and the first 8 weeks of lactation was studied over four successive calving seasons. Calves were weaned at either 150 or 240 days.

Cows offered most concentrates and those whose calves had been weaned early in the previous year produced more milk per lactation (P < 0·01) than other cows but weaning age did not affect yield/cow per year. Data for each treatment in each year were considered as a separate class. Regression analyses showed that milk yield increased with cow weight at calving and with calf birth weight. Changes in cow weight during early lactation, after adjusting for initial weight, were directly related to milk yield.

In a concurrent experiment, three groups of heifers were confined in pens and given sufficient amounts of a complete diet to promote either gain, maintenance or loss of weight during lactation. Heifers that gained or maintained weight produced significantly (P<0·01) more milk of a higher solids-not-fat and protein content than those which lost weight. Food intake had a significant (P < 0·01) positive effect on milk yield but the effects of weight and weight change on milk yield were negative after adjusting for food consumption.
Cereal processing and food utilization by sheep 1. The effect of processing on utilization of barley by early-weaned lambs
Authors: Fraser C. , Ørskov E. R.
Published: September 2010

In Experiment 1, 24 early-weaned, male lambs were given ad libitum a diet based on either rolled or whole barley, both pelleted through a 7·4 mm die. Growth rates were 360 and 409 g/day, food conversion ratios 2·80 and 2·56 kg dry matter/kg gain, and organic-matter digestibilities 77·8 and 80·4% for the two diets respectively. In Experiment 2, 12 early-weaned, female lambs were given a diet based on either whole barley pelleted through a 7·4 mm die or unprocessed barley. When the diets were given in restricted quantities those containing unprocessed barley were slightly but significantly higher in digestibility. The feeding of unprocessed barley increased the firmness of subcutaneous fat and the contents of the rumen at slaughter, but decreased liver weight.

In Experiment 3,36 early-weaned, female lambs were given ad libitum diets based on either pelleted rolled barley, pelleted whole barley or unprocessed barley. Growth rates were 260, 270 and 264 g/day; food conversion ratios were 3·20, 3·20 and 3·00 kg dry matter/kg gain organic-matter digestibilities were 80·8, 79·3 and 81·0%, rumen pH values were 5·2, 5·2 and 6·1, and liver weights 728, 788 and 673 g, for the three diets respectively. As in Experiment 2, the subcutaneous fat on the cold carcass was firmer and more acceptable to the butcher when whole barley was given.
Twinning in Israeli-Friesian dairy herds
Authors: Bar-Anan R. , Bowman J. C.
Published: September 2010

The incidence, heritability and effects on lactation performance of twinning in 185 000 calvings in Israeli-Friesian dairy herds are presented. The incidence of twinning in heifer and cow calvings (parities 2 to 6 inclusive) was 0·7 and 5·4% respectively in the large Kibbutz herds and 0·7 and 3·5% in smallholders' herds. The heritability estimate for 144 sires each with over 200 calvings of daughters of parity 2 to 6 was 0·024 ± 0·002. The range of incidence of twinning in these parities among sire progeny groups each with more than 1000 calvings was 2·8 to 7·8 %, apart from one sire, whose daughters had 12·2% twins. His progeny excelled in five characters and as an explanation it is suggested that a rare gene is segregating in the breed with a major effect on the endocrine system and associated pleiotropic effects.
Prediction and evaluation of response to selection with overlapping generations
Authors: Hill William G.
Published: September 2010

In a population in which generations overlap the improvement in performance in successive years resulting from a single year of selection is not constant, for the genes from a group of selected individuals may take many years to pass through the population. A formal method is developed for predicting responses and discounted returns from improvement in populations with overlapping generations including, if necessary, generations of multiplication of breeding stock.

The method is based on a matrix which specifies the passage of genes between the different age groups and sexes. Simple matrix operations can be used to compute the proportion of genes in animals of both sexes and each age in the population at any time which derive from a group of selected animals at an earlier time. The response produced by these selected animals equals the product of their genetic selection differential and the proportion of genes deriving from them. Comparisons are made between responses predicted using this theory and the classical theory of uniform rates of response, and a method is given for computing the time lag of genes passing through the population.

The results are extended to enable computation of discounted returns from improvement.
Nutrition and reproductive performance of dairy cattle 2. Prediction of reproductive performance in first lactation dairy heifers subjected to controlled nutritional regimes
Authors: Ducker M. J. , Morant S. V. , Fisher W. J. , Haggett Rosemary A.
Published: September 2010

One hundred first lactation Friesian dairy heifers were used to investigate the effect of level of feeding n i late pregnancy (83·6 or 64·6 MJ metabolizable energy (ME) per head daily and around the time of first artificial insemination (AI) (weeks 6 to 18 of lactation: 146·8 or 119·8 MJ ME per head daily) on reproductive performance.

Heifers receiving the high level of feeding in lactation had a successful pregnancy rate to first AI of 0·42 compared with 0·63 for heifers receiving the lower level of feeding. Heifers receiving the higher level of feeding in late pregnancy followed by the lower level in lactation had a pregnancy rate of 0·72 o t first AI resulting in a median interval from calving to pregnancy of 75 days compared with figures of 0·35 and 95 days respectively, for heifers receiving the higher levels of feeding throughout the experiment (P< 0·001).

Blood samples were taken from all heifers 2 weeks before and on weeks 1, 5, 9, 13 and 18 after calving, and were analysed for 13 components. Of the blood components measured, only p"-hydroxy-butyrate concentrations, particularly at week 9, were affected by the nutritional treatments imposed and consistently related to fertility (P< 0·01 toP< 0·001).

Milk yield and live-weight change, individually and as the components of net energy output, showed the strongest relationships with reproductive performance (P< 0·01 toP< 0·001). The three variables which together accounted for the highest proportion (0·30) of the variation in days to successful pregnancy were net energy output at AI, (3-hydroxy-butyrate at week 9, and mean tail score in weeks 10 o t 13. These enabled the calving to successful pregnancy interval for an individual or 100 first lactation heifers to be predicted with a 95% confidence interval of ±58 days or ±8·6 days, respectively.