Inclusion of legume in grass pastures optimizes protein values of the forage and promotes improved digestibility. Therefore, we hypothesized that finishing steers on a novel combination of legumes and grass pasture would produce carcasses with acceptable traits when compared to carcasses from steers finished in feedlot systems. In this study, we evaluated the effects of finishing steers on three systems including: grazing legume–grass pasture containing oats, ryegrass, white and red clover (PAST), grazing PAST plus supplementation with whole corn grain (14 g/kg BW (SUPP)), and on a feedlot-confined system with concentrate only (28 g/kg BW, consisting of 850 g/kg of whole corn grain and 150 g/kg of protein–mineral–vitamin supplement (GRAIN)) on growth performance of steers, carcass traits and digestive disorders. Eighteen steers were randomly assigned to one of three dietary treatments and finished for 91 days. Data regarding pasture and growth performance were collected during three different periods (0 to 28, 29 to 56 and 57 to 91 days). Subsequently, steers were harvested to evaluate carcass traits, presence of rumenitis, abomasitis and liver abscesses. The legume–grass pasture provided more than 19% dry matter of protein. In addition, pasture of paddocks where steers were assigned to SUPP and PAST treatments showed similar nutritional quality. When compared to PAST, finishing on SUPP increased total weight gain per hectare, stocking rate, daily and total weight gains. The increase of weight gain was high to GRAIN than SUPP and PAST. Steers finished on GRAIN had high hot carcass weight, fat thickness and marbling score when compared to PAST. However, these attributes did not differ between GRAIN and SUPP. Abomasum lesions were more prevalent in steers finished on GRAIN when compared to PAST. Results of this research showed that it is possible to produce carcasses with desirable market weight and fat thickness by finishing steers on legume–grass pasture containing oats, ryegrass, white and red clover. Moreover, supplementing steers with corn when grazing on legume–grass pasture produced similar carcass traits when compared to beef fed corn only.

Milk temperature was measured automatically during milking with a view to detecting silent oestrus in dairy cows. A total of 38 silent oestrous periods were studied, based mainly on ovulation and milk progesterone levels together with visual observation.

In 78·9% of silent oestrous periods, a significant increase in milk temperature amounting to a mean of 0·6 (s.e. 0·07)°C was found, and this was highly correlated (r = 0·90) with an increased body temperature. In most silent oestrous periods increases in milk and body temperatures and ovulation with milk progesterone levels below 2 μg/l were found, the oestrous cycles being characterized by typical progesterone profiles. In some cows increases in milk and body temperatures and ovulation during a silent oestrous period were associated with non-typical progesterone profiles although most of these occurred shortly after parturition.

Oak acorn contains high levels of tannins which have capacity to form complexes with proteins and consequently reduce their availability and as a result it could reduce colostrum quality and immunoglobulin (Ig) synthesis. Thus, the aim of this experiment was to investigate the effects of dietary oak (Quercus persica) acorn (OA) level during the last 60 days of pregnancy on colostrum composition and plasma metabolites and IgG level of goats and their kids. In all, 24 multiparous pregnant goats (41.7±2.3 kg BW) were assigned into one of the three experimental diets consisted of control diet (without OA) and diets containing 20% (OA20) or 40% (OA40) OA on dry matter basis. Goats fed OA40 had lower BW change compared with other groups (P⩽0.05). Kids birth weight was not affected by experimental diets (P>0.05). Goats fed OA containing diets had lower plasma glucose, triglyceride and Fe concentrations compared with those fed the control diet (P<0.01). Plasma IgG (P<0.01) and urea (P<0.05) concentrations were lower in goats fed OA40 compared with others. Animals fed OA containing diets had higher plasma alanine aminotransferase than those fed the control diet (P<0.05). Goats fed OA40 produced colostrum with lower fat (P⩽0.05) and lactose (P<0.01) contents compared with other animals. Goats fed OA containing diets had lower colostrum IgG level than those fed the control diet (P⩽0.05). Kids plasma total protein concentration was not affected by experimental diets (P>0.05), whereas kids born from goats fed OA containing diets had lower plasma IgG level compared with the control diet (P<0.01). It is concluded that feeding OA during the last 60 days of pregnancy decreased colostrum quality which may have adverse effect on kid’s survival.

Visible (Vis) and near infrared (NIR) reflectance spectroscopy is a rapid and non-destructive technique that has found many applications in assessing the quality of agricultural commodities, including wool. In this study, Vis and NIR spectroscopy combined with multivariate data analysis was investigated regarding its feasibility in predicting a range of fibre characteristics in raw alpaca wool samples. Mid-side samples (n = 149) were taken from alpacas from a range of colours and ages at shearing time over 4 years (2000 to 2004) and subsequently analysed for fibre characteristics such as mean fibre diameter (MFD) and standard deviation (and coefficient of variation), spin fineness, curvature degree (and standard deviation), comfort factor, medullation percentage (by weight and number in white samples only) using traditional reference laboratory testing methods. Samples were scanned in a large cuvette using a FOSS NIRSystems 6500 monochromator instrument in reflectance mode in the Vis and NIR regions (400 to 2500 nm). Partial least squares (PLS) regression was used to develop a number of calibration models between the spectral and reference data. Mathematical pre-treatment of the spectra (second derivative) as well as various combinations of wavelength range were used in model development. The best calibration model was found when using the NIR region (1100 to 2500 nm) for the prediction of MFD, which had a coefficient of determination in cross-validation (R2) of 0.88 with a root mean square standard error of cross validation (RMSECV) of 2.62 μm. The results show the NIR technique to have promise as a semi-quantitative method for screening purposes. The lack of grease in alpaca wool samples suggests that the technique might find ready application as a rapid measurement technique for preliminary classing of shorn fleeces or, if used directly on the animal, the technology might offer an objective tool to assist in the selection of animals in breeding programmes or shows.

The exposure of adult, female, Mediterranean goats during anoestrus to males with induced sexual activity via photostimulation, induces a very high percentage of ovulations. The present work examines the ability of photostimulated bucks to improve the male effect-induced reproductive response of young does over that induced by non-stimulated bucks. A 2×2 factorial experiment was designed, consisting of doe age and buck photoperiod treatments. During seasonal anoestrus, 41 does aged 7 (n=19) or 10 (n=22) months were subjected to the male effect on 10 April; half of each group was exposed to males rendered sexually active by prior exposure to 3 months of long days (16 h of light/day) from 31 October (PHOTO bucks), and half to males maintained under the natural photoperiod (CONTROL bucks). Oestrous activity was recorded daily by direct visual observation of the marks left by male-worn marking harnesses over the 32 days following the bringing of the sexes together (introduction). Doe body weight and body condition were determined weekly. Ovulation was detected by measuring plasma progesterone concentrations twice per week over the 3 weeks after introduction. The ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy and productivity were also determined. The interaction doe age × buck photoperiod treatment had no effect on any outcome. The percentage of females showing ovulation or oestrus was higher in the does exposed to PHOTO bucks (85% v. 43% for those exposed to CONTROL bucks) they also showed higher fertility (75% v. 43%) and productivity (1.05±0.17 v. 0.57±0.16 kids born per doe serviced) (all P values at least P<0.05). The 10-month-old group showed higher percentage of females showing ovulation, oestrus, fertility and productivity than the 7-month-old does after the male effect (females showing ovulation: 82% v. 42%; showing oestrus: 73% v. 42%; fertility: 73% v. 42% and productivity: 1.09±0.17 v. 0.47±0.14 goat kids born per doe serviced; respectively, all P values at least P<0.05). The present results show that the use of photostimulated males improves the reproductive performance of 7- and 10-month-old does, and may contribute towards increasing their productivity and lifetime reproductive performance.

This study aimed at modeling the relative importance of food intake on growth heterogeneity among cultured sea bass (Dicentrarchus labrax). First, we designed an individual growth model comprising five compartments (Energy intake, Losses, Net Energy, Recovered Energy and Maintenance). This model was calibrated with a first experiment carried out in eight tanks; A total of 130 juveniles (11 g) per tank were fed by a self-feeder (84 days, 20°C, 16L : 8D, 30 g NaCl/l). A second experiment was performed to better understand the relation between individual food intake, individual growth and growth heterogeneity, using the model as a tool for a hypothetico-deductive approach on growth heterogeneity (135 passive integrated transponder-tagged fish, same rearing conditions as above and individual food intake measured by X-ray every 14 days). The tested hypotheses were that food intake was (a) homogeneous, (b) proportional to the fish weight (i.e. to W1.00) X-ray (c) proportional to W0.66 and (d) reflected by the X-ray measurements of food intake. For each hypothesis, a simple linear regression between experimental and simulated results was produced. The Fitness indicators of these analyses, together with their confidence intervals (calculated by bootstrapping), allowed testing the relevance of these hypotheses. The analysis indicated that growth heterogeneity was largely accounted for by individual variations of food intake, as revealed by the X-ray analysis, and that food intake was proportional to W1.00, which suggests a dominance hierarchy where small fish are incapable of feeding maximally.

Although hay is the foundation of most equine diets, horse owners rarely ask for biochemical analysis and the routine practice is to choose hay based on its ‘perceived‘ nutritional value. The present study aimed at exploring the relationship between sensory properties as perceived by sight, touch and smell, and the nutritional value of hay measured by biochemical analysis using a ‘free sorting task’ method. Fifty-four non-expert participants were asked individually to: (1) observe 21 hays samples, (2) group together hays that they perceived as similar for each of the three modalities (hay appearance, odour or texture) and (3) characterize each formed group with a maximum of five descriptive terms. For each modality, results were recorded in a contingency matrix (hays × terms) where only terms cited at the minimum five times for at least one sample, were kept for data analysis. A correspondence analysis (CA) was performed on the contingency matrix to plot both samples and descriptive terms on a χ2 metric map. Then, a Hierarchical Ascending Classification (HAC) was performed on the coordinates of samples in the CA space. Clusters were identified by truncating the HAC tree-diagrams. The attributes that defined the best resulting clusters were identified by computing their probability of characterizing a cluster. Correlations were computed between each biochemical parameter on one hand, and the first two dimensions of the CA map on the other. Finally, correlations between the values of each hay on the first dimension of the three CA maps (appearance, odour and texture) were computed. Hedonic descriptive terms were primarily used for describing odour and texture modalities. For describing hay appearance, participants spontaneously used visual cues referring to colour or aspect. Based on the tree-diagrams resulting from the HAC, 3, 5 and 2 groups were clustered, respectively for appearance, odour and texture description. Digestible energy was correlated to the first dimension on the three CA maps, whereas CP was correlated to the first dimension of the CA appearance map only. While NDF value was correlated to the first and second dimensions on the CA odour map only, ADF content was correlated to the first dimension on the three CA maps. Non-fibre carbohydrates were correlated to the first dimension of the CA appearance map only. The similarity-based approach which is part of the standard toolbox of food sensory evaluation by untrained consumers was well adapted to animal feeds evaluation by non-experts.

Phosphorus (P) losses from dairy farms can severely damage aquatic ecosystems, so it is important to have tools to assess overfeeding of P. This study screened P intake and faecal excretion of different P fractions in dairy cows on conventional and organic farms, compared the P feeding level of the herds against the recommendations and analysed different sampling and analysis methods for assessing the general status of P feeding on the farms. The organic (n=14) and conventional farms (n=15) were of comparable size and were located in southern Sweden. On each farm, feed intake was registered for 10 cows representing four different lactation stages and their P intake was calculated and related to current recommendations. Faecal samples taken from the same cows were analysed for total P (TP) and soluble P. Milk production data for the cows were obtained from the Swedish official milk recording scheme. TP was determined in one slurry sample per farm. More than 70% of the cows studied, representing both conventional and organic herds, consumed P in excess of the recommendations. Conventional herds had higher P content in the ration than organic herds, and lactating cows in conventional herds had higher faecal concentrations of total and soluble P than those in organic herds. However in dry cows, the P content of the ration and soluble P and TP in faeces did not differ between the two management systems. Soluble P was well correlated to TP in faeces, and both were good indicators of P overfeeding.

The effect of ammonia treatment of straw on both the rumen environment and the extent of its microbial fermentation was studied. Four rumen cannulated sheep were randomly given 700 g/day of untreated straw plus urea (US), ammonia-treated straw (TS) and alfalfa hay (AH) in a change-over design with three periods. Rumen pH was lower and ammonia-nitrogen and total volatile fatty acid (VFA) concentrations were higher (P < 0·001) with AH than with US or TS. With the straw diets, TS promoted a lower pH than US (P < 0·05), but differences were less than 0·3 units and the mean pH was never below 6·5. There were no differences between the straw diets in ammonia-nitrogen or VFA concentration (P > 0·05). When untreated barley straw (BS) and treated straw (TS) were incubated in situ disappearance of dry matter (dDM) at 12, 24 and 48 h (P < 0·01) and neutral-detergent fibre (dNDF) at 48 h (P < 0·001) were higher with TS. In vitro incubation showed a higher gas production with TS only after 36 h (P < 0·05) whereas gas from BS fermentation was higher up to 14 h (P < 0·05). Among diets, dDM, dNDF and gas production with US were numerically higher than with TS or AH throughout, although few significant differences were observed, except for a higher dDM at 12 (P < 0·01) and 24 (P < 0·10) h and a higher dNDF at 12 h (P < 0·10). Particle-associated enzymes were extracted from BS and TS incubated in the rumen for 4, 8, 22 and 24 h. Results ofxylanase and cellulase activities support those of straw incubation, with a drop between 4 and 8 h in TS diet. The concentration of residual phenolics per unit of incubated straws after 12 and 24 h show that phenolics release to the media was higher with the TS diet. Daily changes of phenolic concentration into rumen liquid was also higher with TS than with US (P < 0·001). The increased release of straw phenolics by ammoniation reduced the potential for rumen degradation of straw, mainly in the first hours of the fermentation period.

The objective was to elucidate the influences of two analytical methods, which employed neutral detergent or enzymes, on the digestion of carbohydrate fractions in the rumen and post-rumen of steers. Structural carbohydrates in diets and digesta were directly measured using both procedures and the contents of non-fibre carbohydrates (NFC) and non-fibre non-starch polysaccharides (NFSP) were estimated by subtracting the structural carbohydrates and other components from the organic matter. Carbohydrate sources were Italian ryegrass and rolled barley in the control diet and, in each of other three diets, Italian ryegrass and rolled barley plus either beet pulp, citrus pulp or soya-bean hulls. All diets contained similar proportions of dry matter as crude protein, structural carbohydrates and NFC but the starch proportion of the NFC was different in each diet, as follows: control (0·62), beet pulp (0·48), citrus pulp (0·30) and soya-bean hulls (0·63). Four Holstein steers with ruminal, duodenal and Heal cannulas were offered the four diets in a 4 × 4 Latin-square design. Estimated digestibilities of the structural carbohydrates in the rumen and the whole tract were greater (P < 0·01) when the detergent method was used than when the enzymatic method was used. The maximal difference in the ruminal digestion among the four diets was only 0·05 by the detergent method but 0·17 by the enzymatic method. Conversely, the digestibility of NFC in the rumen, as estimated from the detergent structural carbohydrates was less (P < 0.01) than that estimated from enzymatic structural carbohydrates with no evident differences among the four diets. Starch digestibility in the rumen was extensive for all diets but the ruminal digestibility of NFSP was much lower in the control and soya-bean hull diets, especially when it was estimated using the detergent method. The duodenal flow of microbial protein was greater (P < 0·05) for the beet pulp and citrus pulp diets than for the control. The acetate concentration of the ruminal fluids ranged from 84 for the control diet to 128 mmol/l for the soya-bean hulls diet. The digestion of carbohydrate fractions and the fermentation characteristics in the rumen suggested that the enzymatic method is the more appropriate method for fractionating carbohydrates.

Castration of male ruminants is a common livestock management practice, but induces pain. However, little is known about the effectiveness of multimodal analgesia compared to local anesthesia (LA) alone in reducing pain associated with burdizzo castration in sheep. This study aimed to monitor the pain response induced by castration in sheep and to assess the efficacy of analgesia strategies. Twenty-four 12-month-old male Texel sheep were burdizzo-castrated after administration of physiological serum (Burd), local anesthetic (Burd+LA) or LA plus non-steroidal anti-inflammatory drug (Burd+LA+NSAID). Sheep responses were monitored using behavioral and physiological indices of pain. Sampling occurred from 24 h pre-castration to 78 h post-castration, split into four periods based on the duration of analgesia: P0 (T-24 to T-1 h), P1 (T0 to T+2 h), P2 (T+3 to T+32 h) and P3 (T+36 to T+78 h). Behavioral indices were attention and head position, ear position, position of the eyelid, other facial expression, standing/lying postures, postures of the legs, clinical signs and abnormal activities. Physiological indices consisted in indicators of inflammation (haptoglobin, serum amyloid A (SAA), body temperature), hypothalamo–pituitary–adrenal axis (cortisol, non-esterified fatty acids, glucose), autonomous nervous system (heart rate variability (HRV)) and oxidative stress. The variables contributing most to discrimination of the period×treatment groups were analyzed by factorial discrimination analysis. Pre-castration (P0), there was no significant difference between treatments for all indicators (P > 0.05). Post-castration, eight indicators varied significantly according to period and treatment: cortisol, clinical signs, ratio of low frequency/high frequency (LF/HF) bands of the HRV, attention and head position, SAA, haptoglobin, body temperature and glucose. The treatment×periods groups were well discriminated by the 23 indicators. Burd in P0, Burd+LA in P0 and Burd+LA+NSAID in P0, P1 and P2 had low values for all indicators, likely reflecting absence of pain and discomfort. Burd in P1 and P2 and Burd+LA in P2 showed clinical signs and reduced attention, high LF/HF and high cortisol levels, reflecting acute pain. Burd and Burd+LA in P3 had high temperature, high haptoglobin, high glucose and high SAA, but no response from other pathways. These results suggest that (i) behavioral signs of pain were apparent up to 32 h post-castration, (ii) LA was partially effective, but only during its time of action (2 h) and (iii). multimodal analgesia (LA and NSAID) was effective for up to 3 days post-castration. These findings, and especially those related to sheep behavior, can help veterinarians and farmers better detect pain and refine their pain alleviation methods.

The objective of this study was to investigate the relationship between nitrogen (N) partitioning and isotopic fractionation in lactating goats consuming diets with a constant high concentration of N and increasing levels of water soluble carbohydrate (WSC). Eight lactating goats were offered four different ratios of WSC : N in the diet. A two-period incomplete cross-over design was used, with two goats assigned to each treatment in each period. N balance measurements were conducted, with measurement of feed N intake and total output of N in milk, faeces and urine. Treatment, period and infusion effects were tested using general ANOVA; the relationships between variables were analysed by linear regression. Dietary treatment and period had significant effects on dry matter (DM) intake (g/day). DM digestibility (g/kg DM) and N digestibility (g/kg N) increased as the ratio of WSC : N increased in the diet. No treatment effect was observed on milk urea N concentration (g/l) or urinary excretion of purine derivatives (mM/day). Although dietary treatment and period had significant effects on N intake, the change of N intake was small; no effect was observed for N partitioning among faeces, milk and urine. Milk, plasma and faeces were enriched in 15N compared with feed, whilst urine was depleted in 15N relative to feed. No significant relationship was established between N partitioning and isotopic fractionation. This study failed to confirm the potential to use N isotopic fractionation as an indicator of N partitioning in dairy goats when diets provided N in excess to requirements, most likely because the range of milk N output/N intake and urinary N output/N intake were narrow.

The study included 1013 gilts representing 28 one-way crosses among Yorkshire (Y), Landrace (Ld), Lacombe (Lc), Hampshire (H), Duroc (D), Berkshire (B), Large Black (LB) and Tamworth (T) breeds of swine. The crosses were distributed among five cooperating stations and were mated to Poland China boars to evaluate sow reproductivity based on the performance of the first two litters. The traits studied were weight at 112 days of age, age at puberty, percentage farrowing, litter size and weight at farrowing and at 3 weeks. Significant differences between crosses were found for all traits except farrowing percentage. The most prolific crosses were LdxY, HxLd and D x Y which gave birth to 11·0, 11·0 and 10·8 pigs per litter respectively, compared to the overall mean of 9·7 Ld x Y, LB x Lc and H x Ld crosses weaned litters 7·4, 5·3 and 4·9 kg heavier than the 40·5 kg mean for all crosses. Using percentage farrowing multiplied by litter 3-week-weight for the two litters as a measure of sow productivity, Ld x Y and LB x Lc crosses ranked highest. The breeds that had the best combining abilities for 3-week litter weight were Ld, Y, LB and Lc, however their specific combining abilities are important and hence not all crosses between these breeds produced superior performing crossbred sows. Overall, the Ld x Y was the most precocious, farrowed and weaned the greatest number of pigs per litter and had the heaviest litters at 3 weeks post-farrowing.

Hampshire and Large White crosses were compared with purebred Large White pigs for litterproduction and post-weaning performance. Crossbreeding did not influence either litter size or total litter weight at birth but crossbred litters had 14 % more pigs at weaning than purebred litters. Total litter weight at weaning was 13 % greater i n crossbred litters. In two post-weaning trials (23 to 90 kg live weight), where feeding was either ad libitum or restricted according to live weight, Hampshire crosses had advantages over Large Whites in rate and efficiency of gain and killing-out percentage. The cross-breds had shorter carcasses but a greater eye-muscle area due primarily to a greater depth of lean in the muscle. All fat depth measurements indicated that the crossbreds were not significantly leaner than the purebreds and this was confirmed in the restricted trial when the carcasses were subjected to physical and chemical dissection. Hampshire carcasses did have a lower bone content than those of the purebreds, but crossbreeding did not influence joint proportions or lean distribution in the carcass.

Twenty-five Greyface wether lambs were allocated at approximately 40 kg live weight to be slaughtered, to be untreated controls, or to be implanted with 57·5 mg trenbolone acetate plus 8·1 mg oestradiol-17β (treatment To8), 60mg trenbolone acetate plus lOmg oestradiol-17β (treatment To10) or 70mg trenbolone acetate plus 12 mg zeranol (treatment TZ). The control and treated lambs were slaughtered after 63 days. Effects on live-weight gain were small and not significant. On average, hormonal treatments resulted in: (a) significant increases in dressing percentage, gain in carcass weight and carcass protein, kidney weight (g/kg live weight), depth of thorax and in the activity of liver tyrosine amino transferase; and (b) variable reductions in hind leg length, concentration of plasma urea and (g/kg live weight) kidney fat, mesenteric fat and fleece. Significant differences recorded between treatments included the conversion of food into carcass protein (treatments To8 and TO10 v. TZ) and mesenteric fat (g/kg live weight) and fat cover at the 12th rib (treatment To8v To10).

Wafers made from dried ryegrass were fed to castrated male lambs in two experiments of 40 and 30 days' duration. In the first experiment, wafers of chopped feed were prepared which varied in unit density from 0·7 g/ml to 1·0 g/ml. In the second experiment, coarsely ground forage was passed through a ram press with a die of 5 cm diameter and the extruded material was then split into quarter and half wafers or left unsplit as whole wafers. Voluntary intake was measured throughout each experiment.

For the wafers with density of 1·0 g/ml the daily intake of organic matter was 75 g/kg LW0·75 as compared with 64 g/kg LW0·75 for the wafers with density of 0·7 g/ml but this difference was not significant. There was a significant (P < 0·05) interaction between wafer density and sub-period of the experiment. The daily intake of low-density wafers, expressed in g/kg LW0·75, increased throughout the experiment, whereas that of the higher density wafers did not change.

There was no overall effect of package size on organic matter intake, but the interaction between package size and sub-period of the experiment was significant (P · 0·001). The intake of the whole wafers was initially lower than that for the other treatments, but increased throughout the experiment, whereas the intake of the quarter and half wafers remained steady.

Brackish well water (BW) containing 3574 mg total dissolved solids (TDS) per I was compared with desalinated water (FW, 449 mg TDS per I) as a source of drinking water for dairy cows in the hot arid conditions of Kuwait. Friesian-Holstein cows in early lactation were given daily, 12 kg cereal-based concentrate, 12 kg fresh lucerne and 4 kg senescent date palm leaves for 196 days with the experimental treatments being either BW or FW (four cows per water type). Dry matter and water intakes were not affected by water type (P > 0·05). Cows offered BW gained slightly more weight (P > 0·05) than cows consuming FW. Although overall milk yield and composition was unaffected by water type, the decline in milk yield as the experiment progressed was significantly (P < 0·05) less for cows offered BW. Cows offered BW tended to have higher concentrations of minerals and thyroid hormones in plasma than cows offered FW. It can be concluded that water containing 3574 mg TDS per I was an acceptable source of water for dairy cows.

Simulation results of closed MOET schemes have evidenced several problems issuing from selection in small populations using family information and diverse modifications of the original schemes have been proposed. Mate selection, based on linear programming techniques, includes most of the desirable properties of other methods and offers additional advantages. Some applications of this technique to improve the results of dairy cattle MOET schemes with hierarchical and factorial mating systems have been analysed in this note by computer simulation. Other applications of the method are also discussed.

Litter size is essential for an efficient production of rabbit meat. A diallel cross between four maternal lines was carried out and the analysis of the components of litter size has been already done. This paper presents the analysis of litter size traits themselves (total born (TB), number born alive (NBA), number weaned (NW)) and kindling interval (KI), that complete the analysis of the reproductive performance. The 16 genetic groups were distributed in four Spanish farms. The V line was present in all farms in order to be used as reference group. A total of 34 546 parities from 7111 does, were analysed. The crossbreeding parameters were estimated according to Dickerson model. The differences between lines performance were of low magnitude and not significant for litter size traits. The LP line showed the shortest KI followed by H respect to lines A and V. These differences reflected the differences between direct and maternal genetic effects. The differences between the average of all crosses and line V were found to be significant and seemed to be important, being 0.46 for TB, 0.56 for NBA, 0.75 for NW and −2.21 days for KI. The differences between reciprocal crosses for litter size were of low magnitude and non-significant, which indicate that the maternal effects are not important between these lines. In general, the lines did not show significant differences in direct and maternal genetic effects for TB, NBA and NW but there were some significant differences for KI, which ranged from 1.54 to 6.85 days in direct effects and from 0.63 to 3.38 days for maternal effects. A positive and, in some cases, relevant heterosis was found. The largest heterosis was for TB in the HV cross (1.05 rabbits), followed by the AH (0.74 rabbits), AV (0.57 rabbits) and LH (0.55 rabbits) crosses. For NBA, significant heterosis was found in HV (1.11 rabbits) and AV (0.49 rabbits) and for NW in AV (0.90 rabbits), LH (0.70 rabbits) and LV (0.58 rabbits). Favourable and significant heterosis for KI was found in AV and LV crosses, whereas it was unfavourable in AL and in LH. The more recommended crosses were AV and LH, showing the greatest performances on NW, while the cross HV, which shows the greatest performances an NBA, could be highly recommended when cross-fostering is practised to equalise litter sizes after birth, in this situation the lower NW performance observed could be improved.

A recently developed mechanistic mathematical model of the bovine estrous cycle was parameterized to fit empirical data sets collected during one estrous cycle of 31 individual cows, with the main objective to further validate the model. The a priori criteria for validation were (1) the resulting model can simulate the measured data correctly (i.e. goodness of fit), and (2) this is achieved without needing extreme, probably non-physiological parameter values. We used a least squares optimization procedure to identify parameter configurations for the mathematical model to fit the empirical in vivo measurements of follicle and corpus luteum sizes, and the plasma concentrations of progesterone, estradiol, FSH and LH for each cow. The model was capable of accommodating normal variation in estrous cycle characteristics of individual cows. With the parameter sets estimated for the individual cows, the model behavior changed for 21 cows, with improved fit of the simulated output curves for 18 of these 21 cows. Moreover, the number of follicular waves was predicted correctly for 18 of the 25 two-wave and three-wave cows, without extreme parameter value changes. Estimation of specific parameters confirmed results of previous model simulations indicating that parameters involved in luteolytic signaling are very important for regulation of general estrous cycle characteristics, and are likely responsible for differences in estrous cycle characteristics between cows.