bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic aspects of common health disorders and measures of fertility in Holstein Friesian dairy cattle
Authors: Pryce J. E. , Veerkamp R. F. , Thompson R. , Hill W. G. , Simm G.
Published: September 2010

The purpose of this study was to estimate genetic parameters for measures offertility and several health disorders in dairy cows. Data consisted of 33732 records, of which 9163 were on heifers, on 305-day milk yield, health disorders and inseminations. Measures offertility were calculated from calving and insemination dates and included calving interval, days to first service and conception to first service. Health disorders included milk fever, mastitis and lameness. Genetic and phenotypic (co)variances were estimated using restricted maximum likelihood. Heritability estimates for both health disorders and fertility traits were low, ranging from 0·003 to 0·080. All genetic correlations between 305-day milk yield and health and fertility traits, in cows and heifers together, were antagonistic implying that selection for milk yield may have caused a deterioration in health and fertility. The unfavourable correlation between milk yield and health and fertility traits, plus the economic importance of the latter, suggests that future breeding goals should be expanded to include some health disorders and fertility.
The effect of photoperiod on plasma hormone concentrations in wether lambs with genetic differences in body composition
Authors: Francis S. M. , Veenvliet B. A. , Stuart S. K. , Littlejohn R. P. , Suttie J. M.
Published: September 2010

The aim of this study was to determine whether the decrease in plasma growth hormone (GH) levels during a lamb's first autumn is a function of photoperiodic or developmental changes. Wether lambs (no. = 30) from Coopworth sheep selected for low (lean) or high (fat) backfat plus a randomly selected line (control) were subjected to long (16 h light: 8 h dark) or short (8 h light: 16 h dark) photoperiod over a 5-month period after the summer solstice. The animals were regularly blood sampled to determine plasma hormone concentrations. Daily food intake and weekly live weights were measured and the animals were slaughtered at the end of the trial to determine body composition.

Food intake and growth rate were greater for sheep on long than on short photoperiod but photoperiod had no major effect on carcass composition. Mean and basal plasma GH, as well as the number and amplitude of pulses, were not affected by photoperiod, however GH secretion decreased from January to May. Plasma levels ofprolactin, insulin-like growth factor 1 (IGF-1), insulin and glucose were greater in animals under long than short photoperiod, while non-esterified fatty acids (NEFA) were unaffected by photoperiod.

Lean animals had greater mean and basal plasma GH and increased number and amplitude of pulses compared with fat animals. Prolactin concentrations were also greater in the lean than in the fat sheep, while there were no differences in insulin, glucose and NEFA levels. IGF-1 levels were higher in lean than in fat sheep under long photoperiod but lower under short photoperiod.

These results suggest that the decline in plasma GH with increasing age is not affected by photoperiod. While long photoperiod stimulates plasma prolactin and IGF-1 levels as well as intake and growth, the relationship between these parameters is unknown. Hormonal differences between lean and fat genotype sheep are found within the GH axis and prolactin but not within the gonadotropin or insulin axes.
Dietary preferences in adult and juvenile goats
Authors: De Rosa G. , Fedele V. , Napolitano F. , Gubitosi L. , Bordi A. , Rubino R.
Published: September 2010

Six adult and six juvenile goats were used to estimate their feeding preferences when three grasses (ryegrass, barley and brome) and two legumes (clover and alfalfa) were tested. Each grass was separately tested with both clover and alfalfa. A comparison between alfalfa and clover was also performed. The plants were harvested just before their utilization, chopped into 4- to 6-cm pieces and offered to the animals in plastic baskets. Preferences were evaluated by means of a series of seven short-term trials. Each short-term trial consisted of two single-food presentations and one choice-presentation. In the first single-food presentation animals received one of the two plants to be tested. In the second single-food presentation they were offered the alternative plant species. In the choice presentation they received the two species simultaneously. During each presentation animals were allowed to eat for 20 min or take a maximum of 50 bites. In the single-food presentations bite rate, bite mass and intake rate of both juvenile and adult animals were influenced by the plant species offered. Indeed, all goats tended to display a higher intake rate and bite mass for grasses than for legumes. A grass/legume ratio of the intake rates was also computed for each grass-legume comparison. These ratios tended to be higher for juvenile than for adult goats. The results of the choice presentations indicated that food preferences were not affected by age as all goats preferred grasses to legumes and clover over alfalfa. This experiment showed that age may not play an important role in the development of food preferences.
The effects of ensiling and supplementation with sucrose and fish meal on forage intake and milk production of lactating dairy cows
Authors: Keady T. W. J. , Murphy J. J.
Published: September 2010

The effect of ensiling grass and supplementing the resulting silage with water-soluble carbohydrate in the form of sucrose and undegradable dietary protein (UDP) in the form offish meal on forage intake and milk production and composition were evaluated in an experiment involving 63 mid-lactation Holstein-Friesian cows. Herbage from the primary growth of a predominantly perennial ryegrass sward was zero-grazed (ZG) from 19 April to 16 May 1993. The herbage was mown and picked up with a precision-chop harvester and offered as the sole diet, twice daily, to 18 cows which were on average 186 days into lactation. On 13 May, herbage from the same sward was harvested identically to the ZG herbage and ensiled, treated with formic acid at a rate of 2·85 lit grass. At 53 days after ensiling the silage was offered either as the sole diet (SO) or supplemented with sucrose at 10·3 g/kg fresh silage (SS) or supplemented with sucrose and fish meal each at 10·3 g/kg fresh silage (SSF) to 15 cows per treatment which were on average 164 days into lactation. The feeding period was 28 days for ZG and 21 days for the SO, SS and SSF treatments, and the last 7 days were the main recording interval. Prior to going on to the experimental diets all animals were offered a common silage ad libitum and supplemented with 5 kg of a 180 g/kg crude protein concentrate. Dry-matter intakes (DMI), milk yields and milk composition were recorded during the pre-experimental period and subsequently used as covariates in the statistical analysis. For diets ZG, SO, SS and SSF, forage DMI (kg/day), total DMI (kg/day), milk yields (kg/day), fat concentration (g/kg) and protein concentration (g/kg) were 14·4,14·0,13·7 and 13·9 (average s.e.d. = 0·55); 14·4,14·0,14·5 and 15·4 (average s.e.d. = 0·59); 15·4, 14·4, 14·5 and 16·7 (average s.e.d. = 0·42); 36·6, 38·6, 38·6 and 37·5 (average s.e.d. = 2·67); 33·0, 30·7, 32·2 and 32·8 (average s.e.d. = 0·75). Nitrogen (N) digestibility was higher on SO and SSF (P < 0·05) relative to ZG with SS being intermediate, otherwise treatment did not alter (P > 0·05) diet apparent digestibility. Ensilage increased the immediately soluble N fraction (a value) and degradability of N (P < 0·001) relative to ZG. It is concluded that ensilage had no effect on forage DMI but decreased milk yield and protein concentration relative to the parent herbage. The positive response in milk yield due to supplementation of the silage-based diet with sucrose and fish meal and the lack of response to sucrose supplementation alone suggests that nutrients absorbed from the digestive tract of cows offered silage-based diets are more limiting in protein or specific amino acids supplied by fish meal than in energy. The decrease in animal performance due to ensiling may be overcome by supplementation of silage-based diets with UDP at sufficient levels to equate that of the parent herbage.
Plasma biochemical values in the guanaco (Lama guanicoe) and a comparison with the sheep
Authors: Fraser M. D. , Moorby J. M.
Published: September 2010

An initial experiment was conducted to investigate the variability of selected metabolites in the plasma from guanacos. A second experiment directly compared plasma biochemical values for guanacos with those for sheep. During the first experiment, jugular blood samples were collected from five mature castrated guanacos using an embedded experimental design. Weekly blood samples were collected at the same time (09.00 h) on the same day each week for 7 weeks. Daily blood samples were collected at the same time each day (09.00 h) during week 5. On day 2 of week 5, blood samples were collected every 3 h from 09.00 h for a 24-h period. No evidence of a cyclical pattern of plasma parameters was observed on a weekly, daily or 3-h basis. During the second experiment, the metabolic profiles of 11 mature castrated guanacos and 11 mature barren ewes (Merino × Welsh Mountain) were compared. Significant differences in plasma concentrations of all metabolites except urea-nitrogen (guanacos -15·42 mmolll, sheep - 15·60 (s.e.d. 1·506) mmolll) were found with values for guanacosv.sheep as follows: glucose (7·63v.3·63 (s.e.d. 0·268) mmolll); acetate (0·26v.0·48 (s.e.d. 0·035) mmol/l); β hydroxybutyrate (0·06v.0·50 (s.e.d. 0·019) mmol/l); albumin (33·4v.29·5 (s.e.d. 0·93) g/l); and total protein (53·8v.65·6 (s.e.d. 2·12) g/l); (P< 0·001 for all previous variables); non-esterified fatty acids (0·48v.0·29 (s.e.d. 0·048) meq per 1;P< 0·01) and a-amino N (2·44v.2·66 (s.e.d. 0·088) mmolll;P< 0·05). This study indicates that the reference plasma metabolite concentrations of sheep are not suitable alternatives for use for nutritional or veterinary purposes with guanacos, but those of llamas or alpacas are. The results also suggest that energy capture and transport in camelids may be markedly different from that in conventional ruminants.
Comparisons of the effect of genotype and protected methionine supplementation on growth, digestive characteristics and fibre yield in cashmere-yielding and Angora goats
Authors: Souri M. , Galbraith H. , Scaife J. R.
Published: September 2010

Ten Scottish male castrated cashmere-yielding (C) and 10 Angora (A) goats with initial live weights of 38·2 (C) and 32·1 (A) kg respectively were used in a 112-day study in the time period August to December. The goats were blocked within genotypes according to live weight and randomly assigned to one of two treatments: either no supplementation (O) or dietary supplementation (S) with 2·5 g/kg dry matter (DM) intake of rumen-protected intestinally available methionine (Smartamine™ M, Rhone Poulenc, Animal Nutrition, Antony 92164, France) in a 2 × 2 factorial arrangement.

The goats were offered a basal diet in the proportion of 0·6, grass hay and 0·4 concentrate according to their live weight. Diet metabolizable energy (ME) and crude protein (CP) concentration per kg DM were estimated as 9·9 MJ (ME) and 107 g (CP) and DM intake was restricted to 28 g/kg live weight daily. Apparent digestibility and nitrogen (N) balance studies were conducted from days 24 to 40 and 51 to 64. Measurements were made within three time periods of days 0 to 40, 41 to 75 and 76 to 112.

Angora goats excreted less urinary N than cashmere-yielding goats and had lower values for plasma urea and glucose and greater overall retention ofN, associated with a two- to three-fold greater total fibre yield. Cashmere as a proportion of total fibre by weight, (guard hair plus cashmere) varied from 0·27 to 0·43.

The main effects due to methionine supplementation were improvements in live-weight gain and food conversion ratio. Reductions in urinary N excretion and increases in N retention were recorded, which were generally greater for Angora than for cashmere-yielding goats, and were again associated with the larger responses in fibre production. Clear evidence was also obtained for methionine-induced increases in the weight of raw cashmere, although not guard hair up to day 58. This response was obtained in the absence of significant effects on cashmere diameter, although methionine supplementation consistently increased the average diameter of mohair fibres.
Effect of lairage time on levels of stress and meat quality in pigs
Authors: Warriss P. D. , Brown S. N. , Edwards J. E. , Knowles T. G.
Published: September 2010

A total of 1580 pigs killed in three slaughter -plants were held in lairage for ≥ 1 h, 3 h or overnight before slaughter. Blood samples were collected at exsanguination and subsequent carcass and meat quality monitored. Longer lairage reduced stress levels based on the concentration of cortisol, lactate and creatine phosphokinase in the blood. It also reduced the prevalence of pale, soft, exudative (PSE) but increased the prevalence of dark, firm, dry (DFD) meat. Additionally, it produced progressively greater amounts of skin damage caused by fighting between unfamiliar pigs and an overnight lairage reduced carcass yield and backfat thickness. The overall conclusion ivas that a period of between 1 and 3 h rest in lairage was optimal. There was no evidence that leaner, potentially more stress-susceptible pigs reacted differently from fatter, potentially more stress-resistant animals with regard to the effects of lairage time.
Estimation of genetic parameters for litter size in sheep: a comparison of a repeatability and a multivariate model
Authors: de Vries M. J. , van der Waaij E. H. , van Arendonk J. A. M.
Published: September 2010

Genetic parameters were estimated for litter size in two prolific sheep breeds, i.e. the Zwartbles and the synthetic breed Swifter. Genetic parameters and breeding values for litter size in different parities were estimated using both a repeatability and a multivariate animal model. The estimated heritability from the repeatability model was 0·10 for the Zwartbles and 0·12 for the Swifter. For the multivariate model, heritability of litter size in first, second and third parity was 0·05, 0·07 and 0·10 for the Zwartbles and 0·09, 0·12 and 0·09 for the Swifter. Genetic correlation for litter size in Swifter was 0·81 between parity 1 and 2 and 0·99 between parity 2 and 3. For the Zwartbles genetic correlations were all very close to unity. Environmental correlations between litter size in subsequent parities were not constant over parities. Phenotypic variance in litter size in both breeds was 0·309 in first parity and was almost 50% higher in later parities. Based on the results it is recommended to apply a multiple trait model.
Effect of duration of fasting period on short-term intake rates of lactating dairy cows
Authors: Patterson D. M. , McGilloway D. A. , Cushnahan A. , Mayne C. S. , Laidlaw A. S.
Published: September 2010

The effects of duration of fasting on the short-term feeding behaviour of 12 grazing and 12 silage-fed lactating Holstein-Friesian dairy cows were examined. Four groups of three cows were rotated around fasting treatments of 1, 3, 6 or 13 h following a balanced Latin-square design. Herbage intakes for each treatment group were assessed over al-h period.

As intended there were no significant differences in sward characteristics between the experimental plots grazed by cows from different treatment groups. However, total dry-matter (DM) intake, biting rate and DM intake per bite, measured over the 1-h grazing period, increased significantly when the duration offasting was extended from 1 to 6 or 13 h (P < 0·05). There were only minor differences in grazing behaviour following fasting durations ofl and 3, or 6 and 13 h.

In a parallel study, undertaken to assess the influence offasting duration on appetite independently of grazing, four groups of three cows were housed indoors and offered 30 kg of a high quality grass silage. Silage DM intakes, measured over a 1-h period, increased significantly with extended fasting periods (P < 0·01), though silage DM intake was considerably lower than that of grazing cows for each fasting treatment.

These results suggest that dairy cows grazing on good quality swards may be able to compensate for increased degree of hunger by increasing both biting rate and DM intake per bite to increase DM intake rate. Although the DM intakes of silage and grazed grass followed similar patterns of increasing intake with extended fasting duration, DM intake rates were considerably higher in grazing cows for each fasting treatment.
The effect of cross-suckling and presence of additional piglets on sucking behaviour and performance of individually housed litters
Authors: Wattanakul W. , Stewart A. H. , Edwards S. A. , English P. R.
Published: September 2010

Grouping of sows and piglets during lactation can cause performance problems associated with disruption of suckling. Cross-suckling and an increase in the number of piglets at the udder during milk let-down have been observed. To investigate the role of these factors, 24 sows and litters were used to study their independent effect on sucking behaviour and performance. Control sows (C) remained in farrowing pens with crates until weaning at 28 days. In treatment 1 (Tl) on day 14 after farrowing, five piglets were removed from the resident (Rl) litter and replaced by five piglets (cross-suckers; CS1) of the same age from a different litter. In treatment 2 (T2) on day 14, five additional piglets (CS2) from other litters were added to the 10 resident (R2) piglets for a period of 24 h. Behaviours of the sows and piglets were video recorded prior to mixing and for 3 days after mixing. Litter weight gain of 11 was significantly reduced in the week after mixing (2–06,1·61 and 2·00 (s.e.d. 0·18) kg/day, P < 0·05 for C, Tl, T2, respectively). Within Tl the growth rates ofRl and CS1 piglets were not significantly different. In the 24 h after mixing, C, Rl, CS1 and R2 piglets gained weight whilst CS2 lost weight (247,186,182,151 and -116 (s.e.d. 44·2) glday, P < 0·01). On the day of mixing, the proportion of suckling attempts which resulted in milk letdown was reduced in treatment groups (0·93, 0·75 and 0·70 (s.e.d. 0·04), P < 0·02 for C, Tl, T2 respectively) and the proportion ofT2 piglets lying near the sow's udder between milk let-down was higher than on C and Tl (0·15, 017 and 0·29 (s.e.d. 0·06), P < 0·05). There was no significant difference in piglet behaviour from 2 days after mixing. Both cross-suckling and introduction of additional piglets transiently disrupted sucking behaviour and adversely affected the performance of the piglets. Increased competition had a much greater effect than unfamiliarity with the environment, with added cross-sucking piglets being greatly disadvantaged relative to substituted cross-sucking piglets.
Effects of dietary fatty acids on lipogenesis and lipid traits in muscle, adipose tissue and liver of growing rabbits
Authors: Gondret F. , Mourot J. , Lebas F. , Bonneau M.
Published: September 2010

The effects of fat source on lipogenesis and lipid traits of longissimus muscle, liver and perirenal adipose tissue, were studied in 48 New Zealand White rabbits, slaughtered at 11 or 15 weeks of age. Rabbits were offered diets with 20 g added fat per kg, containing either medium-chain (COC: coconut oil), saturated and monounsaturated (PAL: palm oil) or polyunsaturated (SUN: sunflower oil) fatty acids as major components. Diets did not affect growth performance, dressing proportion and tissue weights. Intramuscular lipid content was lower for COC than for SUN and PAL (e.g. 10v.13 and 12 glkg, at 11 weeks, respectively,P< 0·05), whereas lipid content was unaffected by diet in liver and perirenal fat. In muscle, the fat source did not influence the activities of acetyl-CoA-carboxylase (CBX), malic enzyme (ME) and glucose-6-phosphodehydrogenase (G6PDH). In liver, activities ofGSPDH and ME were depressed from the SUN diet, as compared with the COC or PAL diets. The diet-induced variations in enzyme activities in perirenal fat were lower than in the liver and were not significant. Medium-chain fatty acids were found only in tissue lipids of animals given COC. The ratio of polyunsaturated to saturated fatty acids decreased in the order SUN > PAL > COC in muscle and perirenal fat. Thus, polyunsaturated fatty acids exert an inhibition of G6PDH and ME activities specifically in liver. Compared with COC, the addition of SUN to the basal diet increased total lipids and polyunsaturated fatty acids contents in the longissimus lumborum muscle, which might improve the organoleptic and dietetic qualities of rabbit meat.
Effect of method of blood sample collection on adrenal activity in farmed red deer and sheep following administration of ACTH
Authors: Ferre I. , Goddard P. J. , Macdonald A. J. , Littlewood C. A. , Duff E. I.
Published: September 2010

The effect of method of blood sample collection (automatic blood sampling equipment (ABSE)v.manual) on cortisol and progesterone concentrations was investigated in 20 farmed red deer hinds and 20 domestic sheep ewes following dexamethasone and exogenous ACTH administration. Ten animals were subjected to either automatic sampling or manual sampling via jugular venipuncture in 1 week, with the treatment groups reversed in the 2nd week. The ABSE was programmed to collect a blood sample, then deliver 2 mg dexamethasone, collect a further blood sample 120 min later and then inject 100 fig ACTH. Thereafter, samples were collected at 15-min intervals during a 2·5 h period (12 samples in total). In the manual injection and sampling treatment, four samples were collected: (1) before dexamethasone administration, (2) before ACTH administration, (3) 60 min after ACTH administration, and (4) 150 min after ACTH administration. The success rate of blood sampling with ABSE was 80%. The overall mean packed cell volume (PCV) from samples collected by ABSE from both hinds and ewes was significantly lower than that from samples collected manually (P< 0·01) and PCV declined with time in manually sampled animals (P< 0·01). Plasma cortisol concentrations peaked at 45 min after ACTH administration in sheep and deer. In sheep, there was a marked fluctuation in the plasma cortisol concentrations with time. Both deer and sheep showed a reduced cortisol response to ACTH during week 2 irrespective of sampling method suggesting down-regulation of the response to ACTH. Maximum mean plasma progesterone concentration was reached at 15 to 30 min after ACTH administration. No significant differences in cortisol and progesterone responses due to blood sampling method were found in animals receiving prior dexamethasone treatment. This demonstrates that the ABSE has the ability to be used to effectively conduct ACTH stimulation tests without the need to handle the animals during the test.
Effect of food type and location on the attendance to an automatic milking system by daily cows and the effect of feeding during milking on their behaviour and milking characteristics
Authors: Prescott N. B. , Mottram T. T. , Webster A. J. F.
Published: September 2010

Food can be used in an automatic milking system (AMS) to encourage frequent attendance to, and modify behaviour in, an AMS. An AMS was designed such that a cow had to pass from a bedded area through the AMS to enter the feeding area. A visit resulted in milking if the interval since the last milking was greater than 4 h.

Fourteen Holstein-Friesian dairy cows were allowed to attend voluntarily an AMS for 15 h/day for three 8-day periods. In period 1 the cows were given forage in the feeding area and concentrates in the bedded area but in period 2 this was reversed. Period 3 repeated period 1. The cows were also divided into two groups of seven, only one of which was given 1 kg of concentrates when milked in each period in a cross-over design.

Visits per cow per day increased when the cows were given forage in the feeding area (6·0 v. 4·1 (s.e.d. 0·08) P < 0·05) but milkings per cow per day were only slightly different (2·6 v. 2·4 (s.e.d. = 0·02) P = 0·052). Feeding forage in the feeding area modified forage-eating behaviour by reducing the number of bouts (4·9 v. 7·6 bouts per cow per day, P < 0·05) and total forage eating time (209 v. 289 min per cow per day (s.e.d. = 33·6), P < 0·05). The cows also tended to spend less time lying (529 v. 620 min per cow per day (s.e.d. = 43·2) P = 0·051).

There was no effect of feeding/not feeding concentrates in the milking stall on visits per cow per day or milkings per cow per day. However, feeding tended to create more shuffling behaviour during the automatic teat cup attachment process (3·4 v. 6·7 shuffling bouts per milking (s.e.d. 2·07) P = 0·053) but there were no effects on the levels of kicking, successful teat cup attachment rate, vocalization, elimination, hesitations in mounting a step or poor rear leg positions. The cows tended to adjust to a more accessible stance during both the automatic attachment process (from 17% of milkings exhibiting poor leg positions at the start of attachment, to 10% at the end, P < 0·01) and over the course of the experiment (from 26% to 10%, P < 0·02). There was a trend for cows who were not fed to milk out quicker than those who were fed for all milkings per day combined (733 s v. 811 (s.e.d. 43·3) s P = 0·074) but there were no other effects on yield, milk flow rate from the udder or time taken to milk out for all milkings through the day combined or just the first milking of the day.

Feeding concentrates in the feeding area can be used as an alternative to feeding forage in the feeding area, but there is no need to feed concentrates in the milking stall. Feeding cows while they were being milked did not improve their behaviour or milking characteristics.
Genetic parameters for lamb birth weight in spring and autumn lambing
Authors: Al-Shorepy S. A. , Notter D. R.
Published: September 2010

Genetic parameters for birth weight were estimated for two sets of spring-born and one set of autumn-born lambs of the same breed composition and genetic origin using a model that included random additive, additive maternal, permanent environmental maternal, litter and residual effects. Litter effects were significant for all data sets, indicating that within-year effects of common environment and (or) non-additive genotype were important for birth weight and should be included in genetic evaluation programmes. Estimates of variance components for autumn-born lambs differed significantly from those obtained from spring-born lambs or from the combined data. In contrast, estimates obtained for the two sets of spring-born lambs did not differ from those obtained when data on all spring-born lambs were pooled. The estimate of h2 for birth weight in spring-born lambs was over twice as large as that obtained for autumn-born lambs (0·26 v. 0·22).In contrast, the across-year repeatability of ewe effects was much larger in autumn lambs (0·41 v. 0·26) as was the full-sib littermate correlation (0·73 v. 0·49). Mean birth weights were also 0·4 to 0·6 kg less in autumn lambs. These results suggest that negative effects on birth weight that have been reported for lambs gestated during summer in equatorial and subtropical regions are also manifested (albeit at reduced levels) in less extreme climates (in this case, 37°, 15' N latitude and 654 m elevation) and that maternal variation exists in the ability of the ewe to maintain adequate lamb birth weights in autumn lambing systems.
The determination of the age of ostrich carcasses from ossification of the pectoral girdle (ossa cinguli membrii thoracici)
Authors: Sales J. , Mellett F. D.
Published: September 2010

Although the extent of ossification between the caracoid and clavicle bones of the pectoral girdle (ossa cinguli membrii thoracici) in the ostrich carcass can be used to determine between ossification classes within the age range 8 to 14 months (considered as the optimal time of slaughter of ostriches), it is not an accurate tool for estimating the exact age at slaughter. It is possible to distinguish between carcasses originating from the birds between 10 and 12 months of age, at which ostrich meat toughens.
Frequency of subclinical mastitis and observations on somatic cell counts in ewes' milk in northern Greece
Authors: Stefanakis A. , Boscos C. , Alexopoulos C. , Samartzi F.
Published: September 2010

Somatic cell counting by the Coulter Counter method, California mastitis test and bacteriological examination were performed on milk samples taken at fortnightly intervals throughout lactation from healthy primiparous and iniiltiparous ewes of the Chios and Karagouniki breeds and from healthy ewes in five grazing flocks in northern Greece.

The proportion of the bacteriologically positive milk samples was 0·22. The prevalence of subclinical mastitis ranged, between the flocks, from 29 to 43% of the ewes. Subclinical mastitis occurred more frequently in Karagouniki than in Chios eives and in multiparous than in primiparous ewes of both breeds. Coagulase-negative staphylococci and S. aureus were isolated in 44 and 33% of the bacteriologically postive samples, respectively. No parity, breed or flock differences in normal somatic cell count were noticed, but stage of lactation influenced normal somatic cell count both in primiparous and multiparous ewes. The results of this investigation also suggest that (a) ovine milk samples with somatic cell count more than 1000 × 103 cells per ml, should be tested bacteriologically, (b) somatic cell count values between 1000 and 2000 × 103 cells per ml should cause suspicion about the presence of coagulase-negative staphylococci in the milk, and (c) the presence of S. aureus in ewe's milk results in a significant increase in somatic cell count, but the wide range of the values does not permit us to suggest any threshold value. The significant correlation between the results of the Coulter Counter somatic cell count method and the Califortiia mastitis test, indicates that the latter can be used for the determination of somatic cell count in ewe's milk.
Heart rate responses and plasma cortisol and (β-endorphin concentrations in ewes subjected to laparoscopy and its associated handling procedures
Authors: Haresign W. , Williams R. J. , Khalid M. , Rodway R.
Published: September 2010

Two experiments were performed to monitor the stress responses of sheep to intra-uterine insemination by laparoscopy and its associated handling procedures. The results of experiment 1 indicated that both restraint alone and full laparoscopic intra-uterine insemination in animals which had been sedated with 0·2 mg/kg diazepam promoted similar, significant (P < 0·001) short-lived increase in heart rate and plasma cortisol concentrations, but there was no effect of treatment on plasma β-endorphin concentrations. Experiment 2 compared restraint and full laparoscopy, with and without sedation in a 2 × 2 factorial design. The heart rate and cortisol responses following restraint and full laparoscopy were not significantly different, although laparoscopy tended (P = 0·06) to increase the duration of the heart rate response. Sedation with diazepam significantly (P<0·05) increased the duration of the heart rate response but attenuated (P < 0·05) the amplitude of the cortisol response. These results indicate that laparoscopic intra-uterine insemination does cause sheep to mount a typical stress response, but that most of this is attributable to the restraint required to effect insemination. However, the magnitude of the stress responses recorded were much lower than those reported to follow many other husbandry procedures.
Optimum linear selection indexes for multiple generation objectives with non-linear profit functions
Authors: Dekkers J. C. M. , Birke P. V. , Gibson J. P.
Published: September 2010

A method to obtain linear selection indexes that maximize objectives that involve average profit in one or more generations within a planning horizon based on non-linear profit functions, was derived through application of optimal control theory. The method involves simultaneous optimization of indexes for each generation in the planning horizon. Optimum linear indexes were found to be conform indexes derived from selection index theory, with economic values equal to a weighted sum of partial derivatives of the profit function at the trait means which result in each generation of the planning horizon. Numerical procedures to derive optimum indexes are presented. Methods and properties of alternative strategies for selection witli non-linear profit functions are illustrated for selection on egg weight and rate of lay in poultry. In the example, the additional benefit of selection indexes that maximize cumulative net present value of profit over a planning horizon of10 years was small relative to use of traditional selection procedures. Optimal indexes were also derived with a derivative-free non-linear programming optimizer, with identical results. The latter method also allows incorporation of additional constraints.

Possible extensions of the optimal control methodology to address other problems related to optimization of selection over multiple generations are discussed.
Seasonal variations in testis size, libido and plasma testosterone concentrations in British goats
Authors: Ahmad N. , Noakes D. E.
Published: September 2010

The effects of months and seasons of the year on the testis size, libido and plasma testosterone (T) concentrations were studied in 10 young sexually mature male goats over a 12-month period. Testis size was expressed in terms of scrotal circumference, testis diameter and paired testes width while the libido was measured as stimulation and reaction times,number of mounts and services, and libido index. These measurements were recorded fortnightly.

The body weight increased from 33·5 (s.e. 0·95) kg in October, to a maximum of 62·8 (s.e. 1·55) kg in July. All parameters of testis size decreased from October through January with a sharp increase noted in July and August. These parameters were significantly higher in the summer and autumn than in the winter and spring (P < 0·01). The libido in the goats increased from October to a maximum in December, declined gradually to reach the minimum in July, and then improved again in August. Thus, libido was lowest during the summer and highest in winter, the difference being significant (P < 0·01). Plasma T concentrations were high during October, with the lowest values noted in June. An increase in the T concentrations was observed in August, reaching the maximum value in September, the difference being significant (P < 0·01). The T concentrations were significantly higher during autumn than in all other seasons (P < 0·01).
Effect of meal frequency and rate of nutrient supply on the post-feeding behaviour of the pig
Authors: Morgan C. A. , Lawrence A. B. , Hunter E. A. , Oldham J. D.
Published: September 2010

There have been suggestions that positive feedback from the meal may stimulate the performance of undesirable behaviour, such as stereotypies, in the post-feeding period. The aim of this work was to measure the short-term effects of a meal on the post-feeding behaviour of the pig.

Pigs (70 kg live weight) were offered food ad libitum for 7 days and then given a restricted food allowance for 23 days (experiment 1) or 14 days (experiment 2). In experiment 1, the food allowance was given in one, two or three meals per day. In experiment 2, the food allowance was given in two meals per day and comprised ingredients which supplied glucose at different rates (starch, glucose/starch, starch/guar gum). The pigs' posture and behaviour were recorded in three 1-h periods during the day on 2 days consecutively during the ad libitum feeding period (time period 1) and on pairs of days on three (periods 2, 3 and 4: experiment 1) or two (periods 2 and 3: experiment 2) subsequent occasions during food restriction. The meal frequency or estimated rate of glucose supply had no significant effects on posture or behaviour. In both experiments activity increased with the duration of food restriction. In periods 1, 2, 3 and 4 of experiment 1 the proportions of observations spent were: standing 0·244, 0·260, 0·706 and 0·728 (s.e.d. 0·0346); nosing 0·073, 0·094, 0·229 and 0·253 (s.e.d. 0·0169); rooting 0·032, 0·037, 0·108 and 0·133 (s.e.d. 0·0133). In periods 1, 2 and 3 of experiment 2 the proportions were: standing 0·247, 0·302 and 0·446 (s.e.d. 0·0240); nosing 0·045, 0·075 and 0·138 (s.e.d. 0·0113); chewing 0·101, 0·126, 0·155 (s.e.d. 0·0121). In experiment 1 feeding rate increased with duration of restriction (P < 0·001), but was unaffected by treatment. It is concluded that post-feeding behaviour was influenced more by long-term changes in state (i.e. prolonged food restriction) than by short-term effects of the meal.
Thiamin supplementation of diets containing varied lipid: carbohydrate ratio given to gilthead seabream (Sparus aurata L.)
Authors: Morris P. C. , Davies S. J.
Published: September 2010

On the basis of their respective metabolizable energy contents, supplemental marine oil was partially replaced with a maize starch/dextrin mixture in diets containing approximately 500 g crude protein per kg food thus lowering the total dietary lipid concentration from 141·6 to 100·9 g/kg. The basal diets were then supplemented with thiamin hydrochloride at 0·5, 5·0 and 10·0 mg/kg food to produce six test diets in all. After 182 days of feeding, the fish given the diets containing the higher lipid content with a thiamin supplement of 10·0 mg/kg had shown significantly better growth and food utilization (food conversion efficiency and apparent net protein utilization) than the fish presented with the remaining five diets. Thiamin supplements of 5 mg/kg or less resulted in poorer performance amongst the fish given the high lipid diets. The fish given all three of the low oil diets performed poorly by comparison with those given the high lipid, high thiamin diet and performance was comparable with that of the fish given the high lipid diets containing thiamin at 5 mg/kg or less. Proximate carcass composition in terms of moisture, protein and lipid was unaffected in response to diet. Glycogen accumulation in the liver was significantly elevated amongst the fish given the low lipid diet where the thiamin supplement was 5·0 mg/kg or more. The haematology of the fish was not significantly altered in response to diet although elevated haematocrit was associated with decreasing thiamin supplementation. It would appear that for the seabream, lipid and carbohydrate are not exchangeable on the basis of their metabolizable energy content. When given high lipid diets the thiamin requirement of the seabream is in excess of 5·0 mg/kg and increasing the thiamin supplement to 10 mg/kg in high carbohydrate diets made no impact on performance.
Maintenance of villous height and crypt depth in piglets by providing continuous nutrition after weaning
Authors: Pluske J. R. , Williams I. H. , Aherne F. X.
Published: September 2010

Thirty-two piglets weaned at 28 days of age were used to test the hypothesis that maintenance of nutrition after weaning would prevent the normal decline in villous height and increase in crypt depth and hence preserve the structure and function of the small intestine. Piglets were allocated to one of four treatments at weaning: (1) control group killed at weaning; (2) piglets offered a dry starter dietad libitum; (3) piglets offered ewes' fresh milk; and (4) piglets offered ewes' fresh milk plus 20 g t-glutamine per I. Piglets in treatments (3) and (4) were offered ewes' fresh milk every 2 h in a feeding schedule that increased from 1·2 I per piglet on the 1st day after weaning to 2·4 I on days 4 and 5. On the 5th day all piglets were killed and samples of small intestine were taken for histological and biochemical examination. Feeding ewes' milk or ewes' milk plus 20 g L-glutamine per I maintained (P > 0·05) villous height and crypt depth compared with piglets killed at weaning. In contrast, piglets given a dry starter diet had shorter villi (P < 0·001), deeper crypts (P < 0·001), and proportionately 0·21 to 0·28 less protein (P > 0·05) in their intestinal mucosa. Piglets given the starter diet proportionately grew from 0·49 to 0·62 more slowly (P < 0·01), ate the same amount of dry matter (DM;P> 0·05), but consumed proportionately 0·30 less energy (P < 0·001) than their counterparts given the milk diets. No treatment differences in the specific activity of lactase and sucrase were observed (P > 0·05). Significant correlations existed between voluntary food intake and villous height at the proximal jejunum for piglets given the starter diet and ewes' milk (P < 0·05 and P = 0·073, respectively). In turn, villous height was significantly correlated (r = 0·78 to 0·87,P< 0·05) with the rate of body-weight gain after weaning in these two groups. For piglets offered ewes' milk plus glutamine, an increase in DM intake was associated only with increases in crypt depth (P < 0·01). These data show that the structure and function of the small intestine can be preserved when a milk diet is given after weaning, and suggest an association between food intake and villous height in determining post-weaning weight gain.
A two-diet system andad libitumlactation feeding of the sow. 2. Litter size and piglet performance
Authors: Neil M. , Ogle B.
Published: September 2010

Sixty gilts were allotted to one of the following feeding regimes: CR, a conventional diet offered at a restricted level according to Swedish feeding standards; SA, a simplified gestation diet (mainly oats and barley) offered at a restricted level and a conventional diet offeredad libitumduring lactation; CA, a conventional gestation diet offered at a restricted level and the same diet offeredad libitumduring lactation. The sows were followed for four parities. Piglet birth weight was unaffected by sow feeding, but differences in piglet live weight were found from 3 weeks of age to the end of the experiment when the piglets were 9 weeks old. CA piglets were heavier than SA piglets at 3 and 9 weeks of age and heavier than both CR and SA piglets at weaning (35 ± 3 days). Litter size was unaffected by treatment as was piglet mortality, whereas the cause of death varied with treatment. Mortality due to trauma was higher among CA piglets than among others, while mortality due to weakness was higher among SA piglets than others and there was also a tendency for higher mortality due to diarrhoea among CR piglets. It was concluded that the CA feeding regime was superior with regards to piglet performance.
Systems of mating to reduce inbreeding in selected populations
Authors: Caballero A. , Santiago E. , Toro M. A.
Published: September 2010

Stochastic simulation is used to compare different systems of mating to reduce rates of inbreeding in selection programmes with phenotypic or animal model best linear unbiased prediction (BLUP) evaluation. Compensatory mating (the mating between individuals from the largest selected families to individuals from the smallest) turns out to be proportionately about 0-30 more effective than minimum coancestry matings for situations with low rates of inbreeding, such as phenotypic selection or high population size, although the advantage is less apparent if common environmental effects are important. A modification of this system of mating is proposed which can be applied for overlapping generations, and this is shown to reduce rates of inbreeding proportionately by about 0-50 more than for discrete generations. Under high inbreeding, however, such as for BLUP selection and small population size, minimum coancestry matings, or even avoidance of sib matings are more effective. A procedure combining compensatory and minimum coancestry matings is also simulated and gives the largest reductions in the rate of inbreeding. The effects of these and other systems of mating on the rate of inbreeding are shown to occur through a reduction in the cumulative effect of selection and a deviation from Hardy-Weinberg proportions.
Variation in ovulation rate and litter size of Cambridge sheep
Authors: Ap Dewi I. , Owen J. B. , El-Sheikh A. , Axford R. F. E. , Beigi-Nassiri M.
Published: September 2010

Ovulation rate (OR) and litter size (LS) were recorded in a flock of Cambridge sheep from 1984 to 1994 and from 1976 to 1994 respectively. There were 1516 and 2480 OR and LS records with means of 3·2 and 2·5 respectively. There was considerable variation in results between years ranging from 2·2 to 3·2 for LS and from 2·8 to 4·2 for OR. Ewe lamb OR was affected by year of recording, some years having higher OR than others. Rearing type (single, twin or triplet) also affected ewe lamb OR, twins having lower OR than both singles and triplets. Ewe lamb OR decreased with later date of birth reflecting a lower age at OR counting. Ewe lamb LS was affected by year of recording and there was also an interaction between date of birth and year indicating that OR decreased with later date of birth in some years but not in others. OR of adult ewes was affected by year of recording which also interacted with age (2, 3 and 4). Generally, OR increased with age but this trend was not observed in all years. LS of adult ewes was significantly affected by year and increased with ewe age (2, 3 and 4). Heritability and repeatability were determined for ewe lamb OR and LS and adult ewe OR and LS in univariate and two-trait analyses using DFREML. Heritabilities of ewe lamb OR (0·18 to 0·21) and LS (0·05 to 0·08) were lower than corresponding adult ewe values for OR (0·19 to 0·34) and LS (0·19 to 0·22). Ewe OR had a lower repeatability (0·43 to 0·55) than LS (0·30 to 0·80). High genetic correlations (>0·9) were obtained for combinations of ewe lamb OR, ewe lamb LS, adult ewe OR and adult ewe LS. The importance of analysing ewe lamb and ewe records separately is discussed as is the value of ewe lamb OR as a selection criterion.
Responses in wool and live weight when different sources of dietary protein are given to pregnant and lactating ewes
Authors: Masters D. G. , Stewart C. A. , Mata G. , Adams N. R.
Published: September 2010

Wool growth, staple strength and fibre diameter are reduced during pregnancy and lactation. This may be due to the increased requirement for protein for foetal growth, udder development and milk production causing a lack of amino acids for wool. Responses in wool production, ewe live weight, lamb birth weight and growth, plasma amino acids and levels of cortisol, insulin and growth hormone were measured when different sources of protein were offered. Either lupin seed (L), fish meal (F) or formaldehyde-treated egg white (E) were included in an oaten hay-based diet offered during the final 3 weeks of pregnancy and first 3 weeks of lactation. Provision of diets containing E or F resulted in significant (P < 0·001) increases in wool growth and trends towards increased staple strength (4 to 6 N/ktex) and clean fleece weights (0·17 to 0·38 kg) compared with the sheep given L. Feeding the E diet increased the concentration of cystine in plasma and sulphur in wool in late pregnancy. Feeding the F diet increased the concentrations of arginine, histidine, lysine and threonine in plasma in early lactation. Ewes given E had higher circulating insulin and increased insulin resistance, compared with sheep given L, on 2 of the 4 days of sampling during pregnancy and lactation during the treatment period. There were no treatment effects on lamb birth weight or growth but ewes given the E diet were significantly (P < 0·05, 3·3 kg) heavier than the ewes given L after 3 weeks of lactation. The results indicate that a lack of protein available for absorption in the small intestine causes reduced wool growth during late pregnancy and early lactation. Wool growth is more sensitive to a reduced protein supply than foetal growth, maternal weight or milk production.