Various procedures for estimating the economic values required to weight characteristics in multitrait selection have been proposed. Some, despite their theoretically sound foundations, are frequently misinterpreted. One such method involves the derivation of economic values based upon accepted economic theories of the firm, profit maximization, and the concepts of marginal economic behaviour. An amplified and more rigorous presentation of this method and its theoretical basis is presented that confirms the basic propriety of the method, clarifies the misinterpretations surrounding its application, and offers additional insights into the potential fallacy of less economically rigorous alternatives.

The response of lactating ewes grazing grass to variations in effective rumen degradable protein (ERDP) and digestible undegradable protein (DUP) supply from concentrates was investigated. During the spring and early summer of 1993, 36 Friesland and 12 Finn Dorset ewes were offered continuous access to permanent pasture (Lolium perenne) and allocated to one of six concentrates (1·2 kg/day) formulated to be iso-energetic and to supply 149 (H), 126 (M) or 103 (L) g ERDP and 70 (A) or 45 (B) g DUP per kg dry matter (DM) in a 3 ✕ 2 factorial design. Herbage intake was estimated using the n-alkane technique and herbage samples obtained for analysis. Ewe milk yields, milk composition, live weights (LW) and condition scores (CS) were recorded weekly. The DM and nitrogen degradability characteristics of the grass samples and concentrates were determined using four Friesland wether lambs fitted with permanent rumen cannulae. Throughout the experiment the grass ERDP: FME ratio was lower than the optimum for maximal microbial protein synthesis. However, using a rumen solid phase outflow rate of 0·05 per h, estimated concentrate ERDP and DUP supplies were similar to those predicted. Increasing concentrate ERDP supply had no effect on herbage intake or LW and CS change but reduced milk fat concentration (P < 0·05) and increased milk lactose concentration (P < 0·05) and the yields of milk (P < 0·01), protein (P < 0·05) and lactose (P < 0·01). There were no significant effects of concentrate DUP supply. In conclusion, it is suggested that concentrate ERDP increased microbial protein synthesis and metabolizable protein supply, a proportion of which may have been deaminated to provide precursors for milk lactose synthesis, such that the marginal response in milk protein yield was 0·210.

Twelve Ayrshire cows in a 16-week changeover design experiment were offered 8 kg hay per day together with a daily supplement of either: A, 8 kg concentrates; B, 6 kg concentrates and 4·5 to 50 kg draff/syrup mixture; or C, 4 kg concentrates and 9·0 to 10·0 kg draff/syrup mixture. The concentrate and the draff/syrup mixture had dry-matter concentrations of 872 and 385g/kg, and contained 229 and 255 g crude protein per kg dry matter respectively. Total daily intakes of dry matter were 13·77, 13·80 and 13·81 kg per cow for treatments A, B and C respectively, and were not significantly different. The mean daily milk yields for treatments B and C were 18·2 and 18·5 kg per cow respectively, and were significantly higher than the yield of 17·3 kg per cow for treatment A. The solids-not-fat and lactose concentrations in the milk, and the mean live weights, were also significantly higher for treatment C than for treatment A. Based on the differences in milk yield and composition between treatments, it was estimated that the metabolizable energy value of the draff/syrup mixture was 12·2MJ/kg dry matter. It is concluded that the draff/syrup mixture was a safe and acceptable food for dairy cows when it replaced half of the concentrate dry matter.

An animal model and an approximative method for calculating repeatabilities of estimated breeding values are used in Finnish dairy cow evaluation. Changes in estimated breeding values over time as daughters accumulate were studied. Special emphasis was given to the accuracy and potential bias in the pedigree indices of young sires. The data set used was the same as in the national evaluation and the traits investigated were protein yield and somatic cell count. The average repeatability in evaluation of bulls without daughters was 0·37. The empirical repeatability defined as a squared correlation between the pedigree index and the final sire proof was only 0·15. The reduction in the repeatability was attributed to the selection on pedigree index. The upward bias observed in pedigree indices was 5 kg (approx. 0·3 of genetic standard deviation). The bias was caused by the overestimation of bull dams' breeding value. Also the proofs of bull sires increased after the second crop of daughters. The correlation between the evaluations of the same sire calculated from two separate equal size daughter groups was 0·91 when the bull had 10 to 50 daughters and 0·87 with over 100 daughters. This illustrates how the relative weight of the pedigree decreases while more progeny information is accumulated in the evaluation.

Thirty single-bearing Merino ewes were used to examine the effect of feeding supplement, from 91 to 140 days of gestation, on changes in chemical composition of the ewes, on the relationships with live weight and body condition score and on the foetus. Ewes grazed a perennial ryegrass pasture and were offered either no supplement or 500 g per head per day of a concentrate supplement from days 30 to 90 and (or) from days 91 to 140 of pregnancy. Maternal carcass and non-carcass components, uterine wall, foetus and placenta plus cotyledons were chemically analysed. Live weight (LW) and body condition score (BCS) on day 140 were both affected by supplementation during late pregnancy, mobilization of protein and fat being lower in animals receiving supplement. BCS accounted for more variation than LW in the carcass fat depot. Because this depot was the most important source of energy from days 91 to 140 of gestation, this suggests that BCS is a useful estimator of mobilization of maternal fat reserves during this stage of pregnancy. The ability to mobilize reserves and protect foetal growth by Merino ewes in southern Europe, where large fluctuations in grass growth rate exposes them to considerable undernutrition as pregnancy proceeds, was confirmed in this experiment. However, when the nutritional regime is extreme, supplementary feeding to the ewes is recommended, in order to make the whole system economically profitable.

In commercial situations dry sows are fed a relatively small amount of food once or twice a day. In group feeding systems this can cause a lot of aggression at feeding time and result in an unequal distribution of food between sows when dominant sows prevent subdominant sows from eating. Ad libitum feeding of a suitable diet may be one way to overcome these problems.

Four groups of 12 multiparous sows were housed in deep straw pens (2.9 m2/sow). They were allocated to one of two feeding treatments involving high or low competition for food. Groups on the high competition (HC) treatment were floor-fed once a day 3.0 kg/sow of a barley-soyabean meal diet in pelleted (8 mm) form. Groups on the low competition (LC) treatment received ad libitum a diet containing 60% unmolassed sugarbeet pulp from a 3-space hopper. The composition of the diets is shown in table 1.

Groups were allocated to treatment after service. Feed intake was recorded regularly, liveweight and backfat thickness were measured every fortnight over a 10 week period.

An experiment was carried out to estimate the concentration of sodium, potassium, whey albumin and total protein of normal and experimentally infected milk from meat breed ewes. Intramammary infection significantly (P > 0·0001) increased the concentration of sodium, albumin and total protein and decreased that of potassium. The potassium decrease was not statistically significant fP = 0·08). The increase in whey albumin and total protein was followed by a significant decrease in the albumin and total protein of blood serum. The increases and decreases of sodium, potassium, albumin and total protein were significantly correlated to the rise in somatic cell count and subsided 3 to 4 days after failure to isolate the infecting micro-organisms from the milk of ewes. Changes in the concentration of albumin could be used in identifying infected mammary glands or to evaluate the virulence of the infecting micro-organism.

Rumen fluid from slaughtered animals is one of the wastes of slaughterhouses released to the environment that, due to its high nitrogen and phosphorus contents, can lead to soil and groundwater pollution. Meanwhile, it contains ruminal microbes and some bioactive compounds such as enzymes, minerals, vitamins and organic acids. This study was designed to examine the potential of rumen fluid as a feed additive. Therefore, the effects of spray-dried rumen fluid (SDR) with 1% maltodextrin on the performance, blood metabolites and some cytokines of sucking dairy calves during the pre-weaning phase were investigated. Forty male Holstein calves, with a mean weight of 39.4 ± 3.7 kg and 7 ± 1 days old, were randomly assigned to four groups (n = 10 calves per group) in a completely randomized design. Experimental treatments were: control diet with no additive (CON); control diet with 0.5 g/day of SDR (SDR0.5); control diet with 1 g/day of SDR (SDR1); and control diet with 1.5 g/day of SDR (SDR1.5). Daily feed intake and average daily gain of calves were not affected by feeding SDR as a feed additive. Cholesterol concentration was significantly affected by the 20th and 40th days of the experiment and decreased linearly by increasing SDR feeding level. Levels of liver enzymes, including aspartate aminotransferase and alanine aminotransferase, in the blood decreased by feeding SDR at day 40 of the experiment. Serum concentration of interleukin-6 at day 20 was not affected by dried rumen fluid feeding, whereas at day 40, a significant effect was observed among experimental treatments. The lowest value was recorded for SDR1.5 v. control calves. At day 20, the serum concentration of interferon-γ was influenced by supplementing SDR, and the highest value was recorded for SDR1.5 calves. The inclusion of SDR with 1% maltodextrin in suckling dairy calves had beneficial effects on the stimulation of calves’ immune system.

Thirty-six male pigs weaned at 28 days of age were used to study the effects of methyl-3-(2- quinoxalinylmethylene) carbazate-N1, N4-dioxide (carbadox) in high- and low-protein diets on the performance of pigs growing between 7 and 32 kg live weight, and on carcass characteristics at the latter weight.

The inclusion of carbadox (55 mg/kg) in a high-protein diet containing 195 g crude protein per kg and 10·2 g lysine per kg had no effect on performance or on carcass characteristics. Pigs offered the high-protein diets grew more rapidly, had a lower food conversion ratio and were leaner at 32 kg live weight than those offered a lowprotein diet containing 146g crude protein per kg and 6·0 g lysine per kg. Supplementation of the low-protein diet with lysine (4·2 g/kg) had no effect on performance or carcass characteristics but the inclusion of carbadox in the low-protein diet increased growth performance and reduced carcass backfat measurements at 32 kg. However, the performance was inferior, and the backfat thickness greater, compared with the high-protein diets. On the other hand, supplementation of the low-protein diet with lysine plus carbadox raised growth performance and reduced carcass backfat measurements to the levels exhibited on the high protein diets.

The description of the growth of the Japanese quails is necessary to characterize the genetic potential of these birds raised in different countries. Thus, the aim of this study was to describe the genetic potential of Japanese quails by conducting a meta-analysis considering studies conducted in different countries. Only data about the subspecies Coturnix coturnix japonica were considered; studies regarding Coturnix coturnix coturnix were not examined. The criteria investigated were BW (W), age (t), year of publication and location of the study. Each set of genetic material within a publication was coded as one study. The Gompertz function was used to interpret the growth of laying quails; thus, each study was represented by Gompertz parameters. The W and t data were applied to estimate the values of Gompertz growth parameters, including BW at maturity (Wm), BW at birth (Wi), maturity rate (B) and inflection point (IP). The age at which the maximum growth rate was achieved (t*) was calculated considering the parameters Wm, Wi and B. To estimate these parameters, random regression was used to randomize the parameter Wm. The parameters estimated for each assay were used in exploratory, grouping, and principal component analyses. The values of Wi ranged from 4.1 to 11.6 g. The values of B ranged from 0.0393 to 0.1039/day, and consequently, the values of t* and IP ranged from 14 to 31 days and 9.21 to 31.03 g, respectively. These results show that there is considerable variability in the growth potential of Japanese quails. To better understand this variation, two groups were examined: Brazil and other countries, according to the grouping of Wi, Wm, B and t*; parameter B was the variable that presented the highest specificity, indicating that both groups modified the maturity rate. For the principal component analysis, the year of publication showed a relationship with the growth parameters but only for studies performed in Brazil. For studies carried out in other countries, the changes in growth parameters were not related to the year of publication. In Brazilian studies, there was a decrease in the maturity rate, but the weight at maturity was higher. Therefore, it appears that different strategies of genetic selection were adopted in Brazil compared to other countries.

An objective and accountable method is needed for deducing the number of registered animals in a breed from registration data. By following the principle that individual breeders register sufficient young females to be certain of having enough replacements for their current breeding stock, the ratios were calculated of the number of adult females in a breed to the number of female registrations, in a given year. Number of breeds considered were 8 cattle, 16 sheep, 8 pigs, 1 goat and 2 equines, all in the United Kingdom or Ireland. This yielded multipliers (4.4 for cattle, 3.3 for sheep, 3.1 for pigs, with confidence limits; and a point estimate of 5.2 for goats) enabling total adult female population to be predicted from a single year's registration data. There was considerable variation between breeds in values of the multiplier, apparently for reasons of breed history and function. This was particularly evident for equines where the two breeds yielded multipliers of 3.8 and 13.9. Multipliers, using registration data that are already in the public domain, can provide an estimate of breed numerical size, which a breed society can either accept or replace with an audited census.

Diets containing 0, 100, 200 or 300 g/kg of maize gluten feed were formulated, using standard tables of ingredient values, to have similar levels of digestible energy (12·9 MJ/kg) and lysine (8·9 g/kg). Each diet was scale fed to four pens of eight pigs, entire males and females, from 37 kg until slaughter at about 85 kg.

There were no problems with diet palatability and no significant differences in live-weight gain, food conversion efficiency or killing-out proportion. With increasing maize gluten feed, dietary lysine increased (8·5, 8·6, 8·9, 9·0 g/kg) and backfat thickness decreased (P1 + P3 = 28·6, 27·2, 25·5, 24·9 mm, P < 0·05). Fat samples were taken from the last rib position on each side of all carcasses. With increasing maize gluten inclusion the fat (inner layer) became darker (P < 0·001) and yellower (P < 0·05). Increasing maize gluten feed also increased levels of linoleic acid (170·4, 195·8, 224·8, 247·7 g/kg total fatty acids; P < 0·001) indicating that progressively softer fat would be produced. The results show that inclusion rates of maize gluten feed up to 300 g/kg did not adversely influence pig performance or carcass characteristics but the appearance and keeping quality of the fat might be adversely affected by higher levels.

The effect of introducing a solution of fatty acids (consisting mainly of ammonium acetate) into the drinking water of Jersey and Friesian cows on the yield and composition of milk was investigated. In short-term experiments there were small increases in milk yield and in the yield of fat in Jersey cows receiving either a high-roughage or a high-concentrate diet and in Friesian cows receiving a high-concentrate diet. Friesian cows receiving a high-roughage diet gave no response. In a long-term experiment extending over 16 weeks of lactation with Jersey cows receiving a high-concentrate diet, there was no immediate effect on milk yield but a greater persistency and overall the yield of fat was increased by 5·9%.

Inclusion of ammonia salts in the drinking water caused increases in the ammonia contents of rumen liquor and of blood but there was little effect on rumen pH or the volatile fatty acids of rumen liquor.

Methane production by ruminant animals is an important anthropogenic source of methane to the atmosphere and is considered an important source to more accurately estimate and to control. It has been known for some time that, in ruminants, diet type and composition can influence methane production, yet there is little quantitative information for contemporary diets used 1n the UK. Attempts to predict methane production from either diet chemical composition or digestibility have not been successful (Moss and Givens, 1990; Johnson et al., 1991). In order to estimate more accurately the amount of methane produced by a ruminant on a given diet, it is essential to establish whether there are interactions of various substrates with forage and to relate this to the rumen environment. Previous work showing interactions has used mainly hay-based diets (Blaxter and Wainman, 1964); as grass silage is now the major forage in the UK, work with this forage was needed.

In a previous paper, pig improvement in Great Britain was assessed for the value of genetic improvements in growth-carcass traits. The benefits are substantial, estimated at €100 × 10 per year. Here, several factors that possibly affect these estimated benefits are examined. These include: 1. comparisons in production systems optimal to improved and to unimproved stocks; 2. interaction of station and farm performance; 3. changes in correlated traits, especially sow weight; and 4. uncertainty about future husbandry and marketing needs.

The conclusion is that, despite appreciable documentation and evaluation, and although the overall benefits are certainly large, there is room for uncertainty about the actual value of past pig improvement work in Great Britain.

Samples from a dark red area of the vastus medialis muscle were taken from eight Canadian Yorkshire-breed pigs after slaughter. Frozen transverse sections were tested for alkali-stable adenosine triphosphatase (ATPase) and the ratio of strong to weak reacting muscle fibres was determined from photomicrographs. The percentage of fibres with strong ATPase reactions was positively correlated (r = 0·82, P<0·01) with animal live weight. This growth-related change is in the opposite direction to that known to occur in the white longissimus dorsi muscle of the pork carcass.

Goat production systems increasingly involve indoor feeding. To facilitate manger design, there is need for information on the ability to reach for food, such as that for cattle given food through tombstone barriers. In the first study, 20 castrated and 20 non-pregnant female Saanens of mean live weight (M) 39·3 (s.d. 14·42) kg were trained to reach, through a vertical tombstone barrier, for concentrate meal placed on a horizontal platform attached to the barrier. The barrier allowed the neck but not the shoulders to pass through. It was hypothesized that horizontal reach forwards (F, distance from mid point of barrier to uneaten meal) and sideways (S, distances sideways from mid point of barrier to uneaten meal adjacent to barrier) would be a function of height of platform above the floor and size of goat. Because of size, eight goats (mean M, 16·4 kg) were unable to reach meal when the platform height was 75 cm. Mean (s.e.) values for F at platform heights 0, 25, 50 and 75 cm were 55·9 (0·68), 58·8 (0·64), 57·8 (0·69) and 41·1 (1·23) cm respectively. Values for S were smaller, but followed a similar pattern (49·4 (0·64), 52·4 (0·56), 53·2 (0·53), 36·6 (1·17) cm). Linear regression of either F or S on M and linear body dimensions (e.g. body length, neck and head length, neck-joint height, withers height) showed high correlations with R2 values being 0·8 or more. In the second study, 10 castrated and 10 non-pregnant females (M, 48·7 (s.d. 14·56) kg) were trained to reach through the tombstone barrier for concentrate pellets 'glued', using molasses, on to a vertical plate. It was hypothesized that vertical reach (V, distance from floor to uneaten pellets) would be a function of distance between barrier and plate (20, 30, 40, 45, 50 cm), height of step (0,14·2, 28·4, 42·6 cm) on which goats placed their forelegs and size of goat. Four goats (mean M, 29·9 kg) were unable to reach pellets when the plate was at 45 and 50 cm. Mean (s.e.) V values decreased with increasing plate distance and increased with step height (e.g. at 0 cm step, 122·4 (1·96), 116·9 (2·05), 109·4 (2·16), 103·9 (2·49) and 96·5 (2·75) at 20-; 30-; 40-; 45- and 50-cm plate distances respectively; at 20-cm plate distance, 122·4 (1·96), 137·5 (2·00), 151·3 (1·90) and 164·3 (2·00) cm at 0-; 14·2-; 28·4-and 42·6-cm step heights respectively). Linear regression of V on body weight and body dimensions (e.g. body length, heart girth, withers height) showed high correlations (R2 > 0·8). It is concluded that for practical purposes, body weight is a satisfactory predictor of reach. The results support the hypotheses. The data will facilitate the design of mangers for goats with body weights and dimensions in the range of those used in the present study.

The growth of a pig depends on the rate at which it eats feed and the composition of the feed. Where feed intake is controlled a pig eats all of its allowance and the problem is to predict its growth. When a pig is given free and continuous access to a feed its rate of intake as well as its growth has to be predicted. Functions which predict intake as dry matter or energy in terms of pig weight can, at best, be only approximations. A different approach to the problem of predicting feed intake is suggested here.

Prediction of intake. Suppose a pig at a protein weight, P kg, seeks to attain rates of protein and lipid retention of PR and LR kg/d respectively. Its protein requirement, PRQ kg/d, is some function of P and PR and its energy requirement, ERQ, is some function of P, PR and LR.

In 1956 the authors showed that formalin could be satisfactorily used for the preservation of skim milk subsequently given to growing pigs from weaning to slaughter (Barber, Braude and Mitchell, 1956). Since then a large proportion of the skim milk used by pig producers in this country has had formalin added to it. No evidence from controlled experiments was hitherto available concerning the value of formalin-treated skim milk for the sucking pig, and it was for this purpose that the experiment reported was carried out.