bluuebunny/crossref_metadata_2025 huggingface dataset:
SELECTION LIMITS: HAVE THEY BEEN REACHED IN THE POULTRY INDUSTRY?
Authors: HUNTON PETER
Published: March 2010

Present emphasis is on the heavy turkey, grown to relatively heavy body weight and subsequently jointed and further processed. Rapid selection for broad-breasted conformation led to problems in natural mating; hence the fertilization of almost all commercial turkey hatching eggs by artificial insemination. Meat chickens have experienced similar selection for growth and conformation. While reproductive performance has not been affected as much as with turkeys, rate of lay, fertility and hatchability of meat chickens has room for improvement. Increased feed intake, in response to selection for growth improvements has led to increased fat deposition, an unwanted feature. Breeding programs for egg production stocks differ fundamentally from those for meat stocks because they are concerned with multiple objectives. Many of these are of low heritibility and some are antagonistic to others. Because of this, selection intensity for any one trait has not been as high as among meat chickens and turkeys. Selection for increased rate of egg production has often been based on "part record;" since this is measured at a time of maximum lay, this trait approaches what may be regarded as a physiological limit, but not necessarily a genetic one. Persistency of lay, on the other hand, shows potential for further improvement. Egg weight and body weight, as they determine feed efficiency, are discussed, as are egg interval and shell quality. No genetic limit has been reached for any of these traits. The application of genetic disease resistance to Marek's disease, for example, affords considerable scope for future improvements. The large resevoir of genetic diversity, coupled with the use of multiple objectives, suggests that even after 40 years of relatively intense selection, genetic variation does not appear to be exhausted. Key words: Genetics, selection, egg production, broilers, turkeys
LACTATION PERFORMANCE OF RANGE BEEF AND DAIRY-BEEF COWS
Authors: BUTSON SARAH , BERG R. T.
Published: March 2010

A milking experiment with range, single-suckled beef cows was conducted over two lactations in 1976 and 1977 at the University of Alberta Research Ranch. A total of 428 cows were milked, ranging from 2 to 10 yr of age and representing four breed groups of Herefords and crossbreds of traditional beef and dairy breeds. Measurements of milk were taken in June and September each year. Milk was extracted following an intrajugular injection of 20 IU of oxytocin. Samples were analyzed for butterfat percent, protein percent and lactose percent. Age and breed of dam differences in milk yields, constituent percentages and yields were assessed. Least squares means of yields pooled over the two periods each year indicated that dams with Holstein and Brown Swiss breeding (DS) yielded more milk than beef crossbreds and purebred Herefords. Average milk yields estimated over 24 h ranged from 5.7 kg/day for Herefords to 7.8 kg/day for DS dams. Compared to 2-yr olds at 100%, 3-yr olds produced 125%, 4-yr olds 136% and mature cows 139% greater yield. The difference between June and September yields was evident between breed groups. Hereford milk production exhibited the greatest decline over 87 days compared to all other crossbreds and DS were the most persistent. Mature cows maintained milk yields better than younger cows, and 2-yr old milk yields declined most noticeably. All crossbred groups produced less butterfat percent and lactose percent content than the Herefords, yet yielded more total energy. All constituent percentages were higher than those reported for commercial dairy cattle. All constituent percentages increased significantly from June to September at approximately 130 days in lactation. A significant decline was noted for all constituent yields in September. Dairy crossbreds demonstrated the highest persistency for all constituent yields. Beef Synthetic dams were intermediate in yield persistency. Average milk yields had negative (P < 0.05) correlations with average constituent percentages. Inter-correlations among constituent percentages were variable and generally small and negative. Key words: Lactation, range cows
A COMPARISON OF MASTITIS DETECTION METHODS IN DAIRY CATTLE
Authors: BATRA T. R. , McALLISTER A. J.
Published: March 2010

The potential value of electrical conductivity, somatic cell count, and California Mastitis Test (CMT) Score in composite milk samples as a screening test for subclinical mastitis was evaluated. The effect of genetic group was significant (P < 0.05) for conductivity and somatic cell count while the effects of parity and month of lactation were significant (P < 0.01) for all the three traits studied. Somatic cell count and CMT score increased from first to fourth parity while there was general trend for increasing conductivity from second to fourth parity. All the three methods identified healthy cows with a good accuracy but failed to recognize a considerable proportion of infected cows. The error rate for misclassification was lowest for CMT score (9.1%), followed by somatic cell count (13.9%) and conductivity (29.4%). Composite strict foremilk samples from cows infected with primary pathogens had significantly (P < 0.01) higher conductivity than those from uninfected cows. Staphylococcus aureus were isolated in 60% of the milk samples and appeared to be in the major organism causing mastitis in this herd. Key words: Dairy cattle, mastitis detection methods
GROWTH AND CARCASS CHARACTERISTICS OF LATE-FATTENING STEERS ON DIFFERENT FEEDING SYSTEMS
Authors: ROMPALA R. E. , JONES S. D. M. , BUCHANAN-SMITH J. G. , WILTON J. W. , BURTON J. H.
Published: March 2010

One hundred Charolais-cross feeder steers (average weight = 280 kg) were allotted to one of five feeding systems: HG, a diet comprising 75% concentrates fed throughout the trial; MG, a diet comprising equal amounts of concentrates and corn silage provided throughout the trial; CS, corn silage fed throughout the trial; CS-HG, corn silage fed to 400 kg liveweight followed by feeding the 75% concentrate diet; and AS-HG, alfalfa silage provided to 400 kg liveweight followed by feeding the 75% concentrate diet. The steers were slaughtered at a constant estimated finish (8 mm fat thickness 11th/12th ribs), in order to grade Canada A1. Grade and carcass characteristics data were collected for all carcasses and a sample of eight carcasses per treatment was selected at random to determine muscle content, fat partitioning and distribution. Average daily rates of gain for steers on HG, MG, CS, CS-HG, and AS-HG were 1.27, 1.25, 0.79, 1.15, and 1.03 kg/day, respectively. The rates of gain for steers on feeding systems HG, MG, and CS declined with time contrary to steers on feeding systems CS-HG and AS-HG, which showed accelerated rates of growth following the backgrounding period. Steers having the highest overall rates of gain had the best feed to gain conversions. Increased rates of gain were related to less time on feed and lighter slaughter weights. Carcass dissection showed no major differences with respect to muscle:bone ratio, wholesale cut distribution, fat partitioning and distribution due to the feeding system employed. Net energy retention for gain, estimated from carcass specific gravity, was much lower than values obtained from NRC. Forage feeding late-fattening steers under 400 kg and subsequent concentrate feeding did not affect major carcass traits. However, late-fattening cattle provided with diets based on large amounts of forages or corn silage may not attain desirable finish at acceptable slaughter weights. Key words: Late-fattening cattle, slaughter weight, carcass, feeding systems, backgrounding
THE INFLUENCE OF FEED ENERGY LEVEL ON GROWTH AND CARCASS TRAITS IN BULLS OF TWO BREED TYPES
Authors: PRICE M. A. , BUTSON SARAH , MAKARECHIAN M.
Published: March 2010

A serial slaughter experiment is described using 48 yearling bulls: 24 Hereford crossbred (HX) and 24 Beef synthetic (SY). Twelve bulls of each breed type were fed a high-energy, mainly grain diet (Hi) and the other 12 a pelleted alfalfa diet (Lo). The two breed types showed similar growth rate and feed efficiency, yet at constant carcass weight (375.2 kg) the HX were fatter (44.2 vs. 37.2 kg) and had less muscle (110.3 vs. 116.8 kg) in the dissected side than the SY. The Hi diet resulted in greater growth rate (1.46 vs. 1.06 kg/day) and feed efficiency (9.5 vs. 12.7 kg/kg), in both breed types, than the Lo diet and resulted in a greater rate of fat thickness accumulation (P = 0.001). At constant carcass weight (375.2 kg), the Hi diet gave more fat (46.9 vs. 34.5 kg) and less msucle (109.0 vs. 118.0 kg) and bone (24.6 vs. 28.0 kg) in the dissected side than the Lo diet in both breed types. It is concluded that biological type and diet can be manipulated independently to produce optimum carcass grades at various carcass weights. Key words: Fatness, feed energy, growth, carcass, bulls, beef production
COMPARATIVE RESPONSES OF BULLS AND STEERS TO TRANSPORTATION
Authors: TENNESSEN T. , PRICE M. A. , BERG R. T.
Published: March 2010

Seven groups of six bulls and seven groups of six steers were transported separately by truck for either 10 min or 2 h. Body weight, rectal temperature, respiratory rate, serum cortisol, and a chute score were recorded before and after trucking. Heart rate was monitored by telemetry in one animal per group. The bulls were significantly heavier than the steers (513 vs. 473 kg), and had significantly lower serum cortisol levels (1.9 vs. 4.8 μmg/dL). The steers showed a significantly greater increase in rectal temperature than the bulls during the 2-h haul (0.5 vs. 0 °C); there were no other statistically significant differences between the two genders. Overall, the reactions of the bulls and steers to trucking were similar and minor. The longer haul caused a greater percentage weight loss (2.2 vs. 1.6%) than the shorter haul. It is concluded that transportation by road for up to 2 h need not be a stressful experience to bulls or steers. Key words: Transportation, steers, bulls, stress
DIGESTIBILITY BY SHEEP AND PERFORMANCE OF STEERS FED SILAGES STORED IN TOWER SILOS AND SILO PRESS BAGS
Authors: RONY DOMINIQUE D. , DUPUIS GILLES , PELLETIER GHISLAIN
Published: March 2010

This experiment evaluated the effect of type of silo on fermentation characteristics, digestibility of single and mixed silages by sheep, and growth performance of steers fed mixtures of corn silage (C) and grass silage (G) at a 1:1 ratio of dry matter (DM). The grass silage (60% alfalfa: 40% grass) harvested at 48% DM and corn silage harvested at 32% DM were stored both in tower silos (TS) and silo press bags (SPB). In each case, on the day of filling, thermocouples were imbedded at different places along the silos. Fermentation temperature of silage stored in SPB dropped more rapidly (P < 0.05) than that of TS after reaching maximum temperature. For the single silages (GST, GSPB, CTS and CSPB) maximum temperatures were 43, 42, 24 and 22 °C, respectively. The single silages and their mixture (GTS + CTS, GSPB + CSPB, GTS + CSPB and GSPB + CTS) were fed to sheep according to a double 4 × 4 Latin square design. Concurrently, 72 Hereford steers weighing 190 kg average live weight were allotted to 12 groups each of six steers and fed four silage mixtures ad libitum according to a complete block design in three replications during 196-day period. Within plant species, type of silo had no effect (P > 0.05) on pH values and silage chemical composition. Voluntary DM intakes were 67.0, 69.4, 49.4 and 46.2 g/kgW0.75 for GTS, GSPB, CTS and CSPB, respectively. No significant differences (P > 0.05) were noted between intake of silages fed as mixtures. Digestibility coefficients of grass silage DM, crude protein (CP) and acid detergent fiber (ADF) were 7.5, 13.8 and 5.5% higher (P < 0.05), respectively, for GSPB than GTS. However, there were no significant differences between digestibility coefficients of corn from SPB and TS. Better DM and CP digestibilities (P < 0.05) were obtained when GSPB was fed in mixture with corn than GTS in mixture with corn. Average daily gain of steers was higher (P < 0.01) with GSPB (0.79 kg/day) than with GTS (0.73 kg/day) fed in mixtures with corn silage. Key words: Silo press bags, tower silos, silage composition, sheep digestibility, steer performance
EFFECT OF COLD EXPOSURE ON MILK PRODUCTION AND ENERGY BALANCE IN THE LACTATING EWE
Authors: McBRIDE G. E. , CHRISTOPHERSON R. J.
Published: March 2010

The lactational performances of shorn ewes chronically exposed to a thermoneutral (21 ± 1 °C) or cold (0 ± 1 °C) environment were compared in two experiments. Heat production measured after 1, 21 and 41 days of cold exposure was increased by 20% (P < 0.05), 43% (P < 0.01) and 55% (P < 0.001), respectively, over thermoneutral control values. In both experiments, cold exposure increased milk fat concentration (P < 0.05). Milk protein and lactose concentrations were maintained in exp. 1 but tended to be increased in exp. 2 as a result of cold exposure. Milk obtained from the cold-exposed ewes was characterized by a relative decrease in short-chain fatty acid secretion (P < 0.01). Although milk composition was affected by cold stress, daily milk production was not significantly altered; as a consequence, total energy lost in the milk tended to be slightly higher for the cold-stressed ewes. The increased energy lost as heat and in the milk during cold exposure resulted in a net energy deficit throughout most of the experimental period. The present data suggest that the lactational performance of a ewe nursing a single lamb is not impaired by chronic exposure to an ambient temperature of 0 °C. Key words: Cold, milk production, milk composition, ewes, energy balance
EFFECTS OF COLD EXPOSURE ON BLOOD FLOW TO THE MAMMARY GLAND AND TISSUES OF THE HIND LIMB OF THE LACTATING EWE
Authors: McBRIDE G. E. , CHRISTOPHERSON R. J.
Published: March 2010

Mammary blood flow was measured in cold-exposed lactating ewes using an electromagnetic blood flow probe on the mammary artery to monitor acute responses, and by injecting radionuclide-labelled microspheres to assess chronic effects. During a period of acute cold exposure (−5 to −15 °C; 4 h) mammary artery blood flow and udder surface temperature decreased markedly when the animal was standing; heart rate increased but rectal temperature remained relatively unchanged. Lying down insulated the mammary gland resulting in increased mammary artery blood flow and udder surface temperature. After a period of prolonged cold exposure (0 °C, 8 wk), udder size and mammary blood flow tended to be lower in comparison to values obtained from ewes housed at 21 °C. Mammary blood flow/100 g tissue was reduced for udder skin (P < 0.07) and teat (P < 0.03) but tended to be higher (P > 0.10) for connective tissue as a result of cold exposure. Calculated mammary blood flow:milk yield ratios were 664 ± 179 for control and 360 ± 110 for cold-exposed ewes. Blood flow was increased to the popliteal fat depot (P < 0.01) and tended to be higher to the gastrocnemius and semimembranosus muscles (P > 0.05) but was decreased to the skin of the thigh (P < 0.05) and lower leg (P < 0.10) as a result of cold exposure. The present results indicate that tissue blood flow redistribution in the lactating ewe during cold exposure is similar to that in nonlactating ruminants and that moderate reductions in mammary blood flow during cold exposure can occur without detrimentally affecting milk secretion in the lactating ewe. Key words: Cold, ewes, mammary blood flow, hind limb blood flow
EFFECTS OF COLD EXPOSURE ON YOUNG GROWING LAMBS
Authors: McBRIDE G. E. , CHRISTOPHERSON R. J.
Published: March 2010

The performance and development of young Iambs housed at 0 ± 1 °C or 21 ± 1 °C were compared in two experiments. Despite similar nutrient intakes for both treatment groups, preweaning growth rate of the cold-exposed lambs tended to be reduced. Bone growth from 4 to 9 wk of age revealed a significant effect of temperature on metatarsal length (P < 0.05). By 10 wk of age morphological differences between the two groups were apparent, especially in terms of smaller ear dimensions (P < 0.01), head (P < 0.10) and metatarsal lengths (P < 0.05) of the cold-exposed lambs. Leg bone lengths after slaughter (13 wk of age) also tended to be shorter for the lambs housed at 0 °C. Organ weights measured after 11 wk of differential temperature exposure were similar for both groups except for slightly increased abomasal and thyroid weights (P < 0.10) in the cold-exposed group. Dry matter and nitrogen digestibilities of a concentrate ration fed to the weaned lambs were not affected by treatment, although nitrogen retention (g/day, g/g digestible N intake) was significantly lowered (P < 0.05) as a result of cold exposure. Key words: Cold, growth, digestion, morphology, lambs
EFFECTS OF SULFUR DIOXIDE ON THE NUTRITIVE VALUE OF SILAGE FOR STEERS
Authors: MATHISON G. W. , MILLIGAN L. P. , WOHLLEBE J. , ELOFSON R. M.
Published: March 2010

Four experiments are described in which the effectiveness of SO2 as a forage treatment before ensiling was evaluated in terms of its influence on silage composition and nutritive value. Retention of added S to the time of feeding was 40% in one experiment and ranged from 17 to 32% in another experiment where SO2 was either applied in the field or at the silo. In general, more water-soluble carbohydrates were preserved in SO2-treated silage. Across all experiments the acetate concentration was reduced (P < 0.05) from 1.7 to 0.9% in the treated silage dry matter (DM). SO2 had no consistent effect on concentrations of other end products of microbial fermentation. In five experiments with legume or alfalfa-grsss silages the apparent digestibility of energy was increased (P < 0.05) by an average 2.6 percentage units whereas DM digestibility was not influenced (P > 0.05) by SO2 treatment. In contrast, energy (P < 0.05) and DM digestibilities were decreased when two cereal silages were treated with SO2. Cattle fed legume or legume-grass silage grew an average of 12.9% faster (P < 0.05) and exhibited a 12.7% improvement (P < 0.05) in DM conversion to liveweight gain in eight comparisons which have been made with SO2-treated forage to date. In contrast SO2 had no influence (P > 0.05) on the performance of steers in one 42-day trial with cereal silage. Further, SO2 was successfully applied in the field as well as at the silo and addition of a silage inoculant to SO2-treated forage was of no value. The use of SO2 as a preservative for legume and alfalfa-grass silage would be economically feasible under some circumstances but at this time treatment of cereal silages with the chemical cannot be recommended. Key words: Sulfur dioxide, silage, silage preservative, steers, nutritive value
PROTEIN LEVELS IN GRASS SILAGE-BASED TOTAL MIXED RATIONS FOR DAIRY COWS IN MIDLACTATION
Authors: BURGESS P. L. , NICHOLSON J. W. G.
Published: March 2010

Total mixed rations containing three levels of crude protein (10, 13 and 16%) were fed ad libitum to a total of 48 cows in midlactation in two experiments. Rations were composed of 60% wilted timothy silage and 40% concentrates on a dry matter basis. Supplemental protein was supplied as soybean meal. Daily nitrogen intake per cow averaged 263, 377 and 510 g in exp. 1, and 305, 435 and 509 g in exp. 2 for the three rations, respectively. Cows fed rations containing 10% crude protein consumed less (P < 0.05) total dry matter and lost more (P < 0.01) body weight than cows fed rations with either 13 or 16% crude protein. Milk production was not affected by protein level in exp. 1 but in exp. 2, 10% crude protein decreased (P < 0.01) actual milk and 4% fat corrected milk yields. Milk fat and protein percentages tended to increase with increasing dietary protein level. Rumen acetate tended to decline while propionate increased (P < 0.05) at higher crude protein levels. Rumen ammonia nitrogen and plasma urea nitrogen levels were closely related to nitrogen intake. Key words: Dairy cows, grass silage, protein, solubility
IN SITU DRY MATTER AND PROTEIN DEGRADATION OF VARIOUS PROTEIN SOURCES IN DAIRY CATTLE
Authors: HA J. K. , KENNELLY J. J.
Published: March 2010

In situ dry matter and protein degradation of various protein sources in the rumen of Holstein steers and cows were studied. The effective degradability of each feed protein was estimated from nonlinear parameters and an assumed constant outflow rate of solids. Protein sources tested were soybean meal (SBM), canola meal (CM) and dehydrated alfalfa meal (Dehy), in exp. 1, and fish meal (FM), CM, CM treated with formalin (FCM) and whole pig blood (BCM) in exp. 2. Nitrogen disappearance, estimated from nylon bags suspended in the rumen, of SBM was less than that of CM; disappearance of Dehy was less than that observed for both oil seed meals. The disappearance of FM was significantly less than all other feed proteins. Formalin treatment of CM was very effective in reducing both dry matter and nitrogen disappearance from the bags, but blood treatment was not effective. Protein degradability estimated from disappearance data was 53.6, 65.8, 41.4, 28.9, 65.5, 22.2, 71.2 and 70.8% for SBM, CM, Dehy, FM, CM, FCM, 30% BCM and 50% BCM, respectively. Key words: In situ, dry matter degradation, nylon bags, rumen, protein degradation, cattle
THE TOTAL AND DIGESTIBLE YIELD OF NUTRIENTS IN BARLEY CULTIVARS GROWN IN THE PEACE RIVER AREA OF ALBERTA FED TO GROWING SWINE
Authors: ANDERSON D. M. , SAUER W. C. , JØRGENSEN H. , THACKER P. A.
Published: March 2010

Seven barrows (Yorkshire × Lacombe) weighing 40 kg at the beginning and 95 kg at the end of the experiment were used in a latin square design experiment to determine the apparent digestibility of selected nutrients in barley cultivars. Seven barley cultivars, representing both six-rowed (Gateway, Klondike, Bonanza and Galt) and two-rowed (Klages, Fairfield and Betzes) varieties, grown on demonstration plots in the Peace River area of Alberta, were tested. Apparent dry matter digestibilities ranged from 82.9% for Galt to 85.7% for Klages (P < 0.05). Protein digestibility ranged from 65.2% for Galt to 69.4% for Betzes. Coefficients of digestion for gross energy ranged from 81.2% for Galt to 84.2% for Klages (P < 0.05). Lysine digestibility ranged from 48.1% for Galt to 61.7% for Bonanza (P < 0.05). Based on long-term average yields, gross and digestible energy yield per hectare were highest from Galt, followed by Klondike, Klages, Fairfield, Bonanza, Betzes and Gateway. Total and digestible yield of protein was highest for Galt and lowest for Klages. However, in terms of total and available yield of lysine, Bonanza ranked the highest. Fairfield had the highest yield of grain, gross energy and digestible energy, based on actual plot yields, followed by Klondike, Bonanza, Gateway, Klages, Betzes and Galt. Yields of total and available protein and lysine from actual plot data were highest for Bonanza and lowest for Galt. Key words: Digestibility, barley, composition, cultivar, swine
EFFECTS OF STORAGE CONDITIONS FOR LARGE ROUND BALES ON RECOVERY AND QUALITY OF ALFALFA HAY
Authors: ATWAL A. S. , SAUER F. D. , ERFLE J. D.
Published: March 2010

Weathering and mold growth in alfalfa (Medicago sativa L.) hay stored at 20% moisture in large round bales was extensive. The losses of dry matter were 9, 40 and 30%, respectively, for hay stored inside, outside and partially protected. Prolonged storage reduced the quality of the edible portion of hay. Key words: Alfalfa hay, digestibility, storage losses, recovery of nutrients
INFLUENCE OF DIETARY CALCIUM-PHOSPHORUS LEVELS ON APPARENT ABSORPTION OF MINERALS AND NITROGEN DURING GROWTH AND REPRODUCTION IN GILTS
Authors: GRANDHI R. R.
Published: March 2010

A higher Ca-P intake during finishing, gestation and lactation periods increased (P < 0.05) the apparent absorption (g/day) of Ca and P during all three periods. Nutrient absorption appeared to differ for Lacombe and Yorkshire gilts. Key words: Calcium, phosphorus, nitrogen, absorption, gilts
REDUCING FEED COSTS: THE CHALLENGE IN PERSPECTIVE
Authors: NICHOLSON J. W. G.
Published: March 2010

The theme for the 1983 AIC conference was "Food at What Cost." In keeping with this theme the Canadian Society of Animal Science Program Committee chose the topic "Reducing Feed Costs" for a symposium. The program was organized by a committee chaired by Dr. D. C. Crober, Nova Scotia Agricultural College, Truro. It was my pleasant duty to act as chairman for the proceedings and to make the introductory and closing remarks which follow. Key words: Feed costs, opportunity feeds
BREEDING FOR FEED EFFICIENCY: POULTRY
Authors: FAIRFULL R. W. , CHAMBERS J. R.
Published: March 2010

In egg-type poultry, variation in egg mass, body weight and change in body weight account for about 50–70% of the variation in feed consumed. In meat-type poultry, about 40% of the variation in feed consumption is attributable to variation in change of body weight (gain), and body weight itself. Past selection, primarily for egg numbers and egg size (egg mass) in egg stocks and for gain in meat stocks, has resulted in a correlated improvement in feed efficiency. Heterosis from breed or strain crosses contributes an average of 6% to improvement of feed efficiency in both egg and meat stocks. The success of direct selection for feed efficiency depends upon variation in feed consumption not attributable to economic traits in present poultry selection programs. There is evidence that such variation exists which could be successfully exploited in poultry. In egg stocks, the evidence is mainly from studies of variation within and between strains. In meat stocks, there is evidence from uni-trait selection studies as well as studies of within and between strain variation. The degree to which such selection would be successful in a multi-trait selection program and the economic viability of such success as compared to alternatives needs to be determined. Improvement of feed efficiency is possible by reducing feed requirements for maintenance and activity, by reducing behaviors causing feed wastage, or by reducing body fat to require less feed energy per unit gain. Feed wastage can be reduced by management techniques. Thus, the exploitation of feed-wasting behavior is not presently necessary. The best prospects are those associated with maintenance energy requirements in both egg and meat stocks of poultry, and the reduction of body fat in meat stocks. It is improbable that the opportunities for breeding to improve feed efficiency have been exhausted, much less identified. Key words: Breeding, feed efficiency, poultry, selection
NUTRITIONAL STRATEGY
Authors: SNIFFEN C. J. , ROBINSON P. H.
Published: March 2010

The contents of Nutritional Strategy are discussed both on a growth and lactation cycle basis. The importance of allocation of feeds over these cycles based on dynamic considerations of feed and animal are proposed. The concept of within-day strategy is discussed with particular emphasis placed on the importance of ruminal microbial ecology and growth, passage and the effect on digestion. Research to date would support that there can be beneficial effects through increased feeding frequency. Further, the literature suggests that controlling fermentation through sequencing the order of feeding may improve productivity. It is proposed that once our understanding of the dynamics of rumen function and the interaction with the animal are more complete it will be possible to select more intelligently feeds that will more adequately provide maximum performance at a maximum profit. Much research is still needed to improve our understanding of the dynamics of rumen and animal metabolism and to determine the animal and feed measurements needed to predict these dynamics more accurately. Key words: Feeding strategy, feeding frequency, degradability, protein, carbohydrate, ruminant
RADDLE MARKINGS AND PRESENCE OF SPERMATOZOA IN VAGINAL SMEARS AS PREDICTORS OF EWES LAMBING TO MATINGS AT THE SYNCHRONIZED ESTRUS
Authors: SHRESTHA J. N. B. , FISER P. S. , AINSWORTH L.
Published: March 2010

A comparison was made of raddle markings and presence of spermatozoa in vaginal smears as a means of predicting which ewes will subsequently lamb. Data were obtained from 308 ewe lambs (6–7.5 mo old) and 464 sexually mature ewes (26–28 mo old) mated to experienced rams at the synchronized estrus induced by treatment with fluorogestone-acetate-impregnated intravaginal sponges and i.m. injection of pregnant mares' serum gonadotrophin. Ewes raddled during 12 h intervals from 0 to 72 h after sponge removal were recorded. Vaginal smears taken 48 and 72 h after sponge removal were examined microscopically for presence of spermatozoa. Of the ewes raddled, 41% of the ewe lambs and 86% of mature ewes, lambed. Corresponding results based on presence of spermatozoa in combined vaginal smears data were 51 and 89%. In ewe lambs, 96% of the ewes with no raddle markings and 100% of the ewes with no spermatozoa in vaginal smears were not pregnant. Corresponding results for mature ewes were 56 and 95%, respectively. This study shows that the presence of spermatozoa in vaginal smears 48 and 72 h after induction of a synchronized estrus improves the accuracy of predicting ewes that subsequently lamb to matings at the synchronized estrus over that based on ewes raddled. This improvement results from a reduction in the number of ewe lambs predicted as bred that failed to lamb (Type 1 error), and a substantial improvement in the percentage of mature ewes predicted as non-pregnant that subsequently lambed (Type 2 error). Key words: Raddle markings, spermatozoa, vaginal smears, synchronized estrus, lambing, ewes
RELATIONSHIPS OF CARCASS FAT AND GRADE TRAITS IN BROILER CHICKENS
Authors: KAZAKOV A. , FRIARS G. W. , HOLT J. D.
Published: March 2010

Three categorical traits, namely breast fat, back fat and fleshing grades, and four continuous traits, represented by abdominal fat pad as a percent of carcass weight, percent carcass fat, percent carcass moisture and percent carcass protein were studied in broilers. The data were derived from a large general study involving four experiments. Results suggested independence of fat and fleshing traits. The various measures of fat and fleshing exhibited an intermediate level of heritability (0.26–0.60). The results suggest that carcass grades may be useful in a breeding program aimed at the reduction of fat in broiler carcasses, particularly where carcass grades can be established on large numbers of identified progeny in a killing plant. Furthermore, the low correlations between fat and fleshing grades negates the industry view that the problems of excess fat is associated with poor fleshing. In fact the genetic parameters indicate that the establishment of lines of fast growing, lean, well fleshed broilers should be feasible. Key words: Broilers, fat, categorical traits
THE GROWTH PERFORMANCE AND CARCASS COMPOSITION OF RAM AND EWE LAMBS FED ON PASTURE OR IN CONFINEMENT AND SLAUGHTERED AT SIMILAR FATNESS
Authors: JONES S. D. M. , BURGESS T. D. , DUPCHAK K. , POLLOCK E.
Published: March 2010

Forty-nine crossbred ram lambs and 62 crossbred ewe lambs were allotted at weaning (average weight 30.6 kg) to pasture (P) or concentrate (C) feeding. The number of lambs per treatment was as follows: rams, 24 P fed and 25 C fed; ewes, 31 P fed and 31 C fed. The lambs were slaughtered after 56, 72, 100 and 121 days on feed. Offal components were weighed, and the alimentary tract was emptied of digesta. One side of each carcass was broken into four cuts (leg, loin, rib, shoulder) which were further separated into fat, muscle and bone. C-fed lambs were 4.0% heavier live than P-fed lambs (P < 0.05) and ram lambs were 9.0% heavier live than ewe lambs (P < 0.05) when evaluated at a constant depth of subcutaneous fat (4.5 mm). However, P-fed lambs required an extra 21 days (P < 0.05) to reach the same fat depth as C-fed lambs. C-fed lambs had greater rib eye areas than P-fed lambs, but carcasses from all treatments had similar proportions of dissected muscle, bone and fat when evaluated at a constant proportion of subcutaneous fat. P-fed lambs had a greater proportion of their empty bodies as head and reticulo-rumen, and a lower proportion as liver and large intestine than C-fed lambs. Ram lambs had a greater proportion of their empty bodies as head, and a lower proportion as caul fat, mesenteric fat, omasum and small intestine than ewe lambs. Distribution of muscle and bone among each of the four meat cuts which were evaluated was similar for all carcasses. Sex and feeding system had only a minor effect on the distribution of the fat depots. In this study, lambs fed on pasture required 21 days longer on feed to reach the same external fatness as concentrate-fed lambs, but produced carcasses of similar composition at slightly lighter liveweights (45.3 vs. 47.1 kg). Ram and ewe lambs spent a similar time on feed to reach a similar finish, but rams were heavier live than ewes (48.2 vs. 44.2 kg). Key words: Lambs, carcass composition, offal, constant fatness
BODY HEAT STORAGE, METABOLISM AND RESPIRATION OF COWS ABRUPTLY EXPOSED AND ACCLIMATIZED TO COLD AND 18 °C ENVIRONMENTS
Authors: McLEAN J. A. , WHITMORE W. T. , YOUNG B. A. , WEINGARDT R.
Published: March 2010

Six cows were alternated between cold (−30 to 0 °C) and 18 °C environments. Rectal (Tr), mean skin (Ts) and mean body (Tb = 0.86 Tr + 0.14 Ts) temperatures, respiration rate (RR) and metabolism per unit body size (M) were measured on first exposure and after acclimatization to each environment. Cows acclimatized to the cold had the same Tr as when acclimatized to 18 °C, but Ts and RR were lower and M was higher in the cold than in the 18 °C environment. Acclimatization appeared to occur in two phases. In the initial phase, lasting less than a day, new 24-h cyclic patterns (greater in the cold than in 18 °C) were established in body temperatures, respiration and metabolism. In the second phase which took longer than 2 days new levels were established in these parameters. The change in heat stored in the body between the two environments was not as great as previously found in an environment with a relatively small but cyclic temperature variation. It is suggested that changes in body heat storage are associated with cyclic or sudden changes in the environment, when it can act as an effective buffer against thermal stress. Key words: Cattle, mean body temperature, body heat storage, acclimatization
POSTWEANING PERFORMANCE OF ARTIFICIALLY REARED LAMBS WEANED AT 21 VS. 28 DAYS OF AGE UNDER TWO POSTWEANING HOUSING REGIMENS
Authors: HEANEY D. P. , SHRESTHA J. N. B. , PETERS H. F.
Published: March 2010

Lambs that had been artificially reared on either lamb milk replacer or calf milk replacer were weaned at 21 or 28 days of age. At weaning, lambs from each milk replacer were randomly assigned to two treatments: (1) transferred on the day weaned to a growing barn, and (2) retained in their liquid-diet pens to 49 days of age, then transferred. Delaying weaning from 21 to 28 days of age essentially eliminated the postweaning growth check for lambs artificially reared on lamb milk replacer and reduced the postweaning growth check for those reared on calf milk replacer. However, the resulting increase in liveweight at 70 days of age was not sufficient to offset the cost of the milk replacer required for the extra week on liquid diet. Postweaning location had only a minor and inconsistent effect on lamb performance indicating that, when facilities are satisfactory, postweaning location is of minor importance for artificially reared lambs. Key words: Lambs, artificial rearing, weaning age, postweaning location
SUPPLEMENTARY COPPER FOR GRAZING BEEF CATTLE — INJECTABLE COPPER GLYCINATE, AND COPPER SULFATE IN FREE-CHOICE MINERAL SUPPLEMENTS
Authors: BOILA R. J. , DEVLIN T. J. , DRYSDALE R. A. , LILLIE L. E.
Published: March 2010

Eight herds of beef cattle from Northwestern Manitoba were selected for Cu supplementation trials during the 1974 and 1976 grazing season (four herds in each season). Supplementary Cu was provided as injectable Cu glycinate or as CuSO4 in a free-choice mineral supplement. The treatments were a combination of: (1) one dose of injectable Cu at the start of the pasture season; (2) two doses of injectable Cu, at an interval of approximately 90 days, with the first dose as in (1); (3) CuSO4 added to mineral supplements to provide 0.25 or 0.50% Cu; and (4) injectable Cu, one or two doses during the pasture season, plus 0.25% Cu as CuSO4 in the mineral supplement. Within each herd a cow and her calf were treated as a cow-calf unit. The concentration of Cu in blood serum was used as an indicator of the Cu status of cattle. Forage samples were analyzed for Cu, Mo and total sulfur, and absorption coefficients for Cu and available Cu were calculated. One dose of injectable Cu at the start of the pasture season, or the inclusion of 0.25% Cu as CuSO4 in the mineral supplement, was effective as a Cu supplement where dietary Mo and total S were less than 3 mg/kg and 3 g/kg dry matter, respectively. When Mo and total S concentrations were higher than 3 mg/kg and 3 g/kg dry matter, respectively, doses of injectable Cu provided at a 90-day interval or a Cu concentration greater than 0.25% in the mineral supplement were effective. More than 0.50% Cu, as CuSO4, was required where Mo and total S in forages were in excess of 10 mg/kg and 3 g/kg dry matter, respectively. Inclusion of CuSO4 in the mineral supplement was adequate as a supplement for cows, but the calves did not appear to consume adequate mineral. Injectable Cu was equally effective for cows and calves. An inadequate transfer of Cu via milk was indicated when a cow, but not its calf was provided with injectable Cu. The beneficial influence upon serum Cu of injectable Cu as opposed to Cu in the mineral supplement, depended upon whether the Cu requirement of the cow or its calf was to be met. The level of supplementation to prevent a drop in serum Cu over the pasture season depended upon the concentrations of dietary Mo and S, and their effect upon the coefficient of absorption for Cu. Key words: Supplementary Cu, grazing cattle, injectable Cu glycinate, dietary CuSO4, free-choice mineral supplements
SPENT CANOLA OIL BLEACHING CLAYS: POTENTIAL FOR TREATMENT OF T-2 TOXICOSIS IN RATS AND SHORT-TERM INCLUSION IN DIETS FOR IMMATURE SWINE
Authors: SMITH T. K.
Published: March 2010

Experiments were conducted to determine the potential for spent vegetable oil bleaching clays to overcome growth depression and feed refusal caused by T-2 toxin, a Fusarium trichothecene mycotoxin. Rats were fed spent canola oil bleaching clays at 0.0, 2.5, 5.0, 7.5 and 10.0% of the diet with and without 3 mg T-2 toxin per kilogram of feed. The bleaching clays largely overcame depressions in body weight and feed consumption caused by T-2 toxin over the 2-wk experiment. Feeding defatted clay at levels corresponding to the levels fed in the first experiment produced similar results while feeding residual oil had very little effect. Feeding spent bentonite produced the same results except that the residual oils were slightly more effective at overcoming T-2 toxicosis than the residual canola oil. Rats were than fed the same levels of spent canola oil bleaching clays for 2 wk and were orally dosed with [3H] T-2 toxin. The fraction of the dose excreted in feces rose consistently with the level of spent canola oil bleaching clays but these increases were not statistically significant. In a final experiment, 48 barrows were fed 0, 5 and 10% spent canola oil bleaching clays for 17 days. Growth and feed consumption were not affected by the level fed. It was concluded that spent canola oil bleaching clays can be used to lessen feed refusal due to T-2 toxin in rat diets. This produce can also be fed to growing swine for short periods without affecting performance. Key words: Rats, swine, T-2 toxin, canola oil, bentonite, clay
EFFECT OF LOW DIETARY ZINC DURING LATE GESTATION AND EARLY LACTATION ON THE SOW AND NEONATAL PIGLETS
Authors: KALINOWSKI J. , CHAVEZ E. R.
Published: March 2010

Twelve pregnant sows were fed semi-purified diets containing either 13 or 63 mg/kg zinc (Zn). The animals were fed the diets during the last 4 wk of pregnancy (2 kg/day) and the two first weeks of lactation (ad libitum). Reduced level of dietary Zn did not affect (P > 0.05) weight changes of sows and no difference (P > 0.05) in food intake occurred during the ad libitum phase of the experiment. Low Zn sows showed lower plasma Zn at 100 (125 vs. 157 g/dL) and 113 (93 vs. 127 g/dL) days of gestation and at 7 (65 vs. 133 g/dL)) and 14 (59 vs. 99 g/dL) days of lactation. The differences were significant (P < 0.01) only during lactation. Copper (Cu), iron (Fe) and ammonia (NH3) concentrations in plasma and alkaline phosphatase activity (APA) of plasma were not affected by treatment. Parturition lasted 2.08 h in control and 4.54 h in low Zn sows (P < 0.1). Zinc, Cu and protein content of colostrum and milk were similar between groups. Low dietary Zn had no effect on litter size, birth weight, number of stillbirths and mortality up to 2 wk of age. Liveweight at 7 days was significantly higher in piglets nursed by low Zn dams but at 14 days of age no significant treatment difference was found. Zinc, Cu Fe, NH3 concentrations in plasma and APA in plasma of piglets were not significantly different at birth or at 7 days of age. At 14 days of age only plasma Zn was significantly reduced (P < 0.05). Low supply of Zn to dams had no effect on the performance of piglets during neonatal life. Key words: Zinc, sows, pregnancy, lactation, piglets
A NOTE ON THE INFLUENCE OF INHERENT MUSCLE QUALITY ON COOKING LOSSES AND PALATABILITY ATTRIBUTES OF PORK LOIN CHOPS
Authors: JEREMIAH L. E.
Published: March 2010

Loin chops from 60 pork carcasses were divided equally among three muscle quality groups (pale, soft, exudative; normal; dark, firm, dry), based upon 45-min and 24-h pH values and visual appearances of the ham and loin muscles. Palatability evaluations indicated only juiciness was significantly influenced by differences in muscle quality. Chops from DFD carcasses were rated more juicy than those from PSE carcasses. There were no significant differences in cooking losses among muscle quality groups. Key words: Pork, muscle quality, palatability, cooking losses
TYROSINE FLUX AND BODY PROTEIN SYNTHESIS IN GROWING LAMBS
Authors: GOPINATH R. , KITTS W. D.
Published: March 2010

Body protein synthesis was estimated in lambs after continuous infusion of 3H-tyrosine for 8 h. The specific activity of plasma tyrosine reached a plateau during the last hour of infusion. Mean (± SE) tyrosine flux values were 80.3 ± 8.8 mmol/day. Mean daily rate of protein synthesis was 485.2 ± 53.4 g/day or 8.4 ± 0.5 g∙kg−1∙day−1. Protein synthesis was positively correlated with body weight and the energy cost of protein synthesis was estimated to be 2.2 MJ/day. Key words: Tyrosine flux, protein synthesis, lambs
INFLUENCE OF FREEZE-STORAGE ON NUCLEIC ACID CONCENTRATIONS IN BACTERIA AND DUODENAL DIGESTA
Authors: HA J. K. , KENNELLY J. J.
Published: March 2010

Separation of bacteria from duodenal digesta prior to storage (−25 °C) resulted in 17 and 27% loss of RNA at 1 and 2 weeks, respectively. Storage of total digesta, with bacterial separation immediately prior to analysis, prevented loss of RNA. Purine base concentrations were not influenced by storage. However, removal of free purine base in digesta prior to analysis is recommended. Key words: Nucleic acids, freeze-storage, bacteria, duodenal digesta
RELATIONSHIPS AMONG UDDER MEASUREMENTS, MILKING SPEED, MILK YIELD AND CMT SCORES IN YOUNG DAIRY COWS
Authors: BATRA T. R. , McALLISTER A. J.
Published: March 2010

Heritabilities, phenotypic and genetic correlations among udder measurements (front teat length, front teat diameter, rear teat length, rear teat diameter, teat distance, udder height), milking speed, and milk yield were estimated for a Holstein line (H) and an Ayrshire-based line (A). Data from 1159 first lactation heifers in the National Cooperative Dairy Cattle Breeding Project were used. A subset of these data from 385 cows measured for the above traits plus California Mastitis Test (CMT) Score were analyzed to estimate relationships among udder measurements, milking speed, milk yield, and CMT score. Front teats were on the average 0.7 cm longer than rear teats. Heritability estimates of udder measurements, milking speed, and milk yield were moderate and ranged from 24% to 57% for the H line, 22% to 61% for the A line and 16% to 51% for the subset of data, except for teat distance in the H line which had a heritability of 5%. Heritability of CMT score was zero. Udders that were closer to the ground tended to have longer and wider teats. High-producing cows milked faster, had lower CMT score, and had udders closer to the ground than low producing cows. Genetic correlations of udder measurements with milking speed and milk yield were small and nonsignificant except for front teat diameter and teat distance which were negatively correlated with milk yield in H line heifers. Key words: Udder measurements, milking speed, milk yield, CMT score, dairy cattle
THE EFFECT OF LACTATION ON OUABAIN-SENSITIVE RESPIRATION OF THE DUODENAL MUCOSA OF COWS
Authors: McBRIDE B. W. , MILLIGAN L. P.
Published: March 2010

Total O2 consumption, ouabain-sensitive and ouabain-insensitive respiration rates were measured for the duodenal mucosa of non-lactating and lactating cows. Support of Na+, K+-ATPase activity, as measured by ouabain-sensitive respiration, accounted for 55% of total mucosal respiration of the cows at peak lactation. In mid-lactation and during the non-lactating period the proportion of O2 uptake inhibited by ouabain declined to 34–35%; the amount of ouabain-sensitive O2 uptake declined from 3.6–4.0 to 2.5–2.8 μL O2/mg tissue per hour. The magnitude of ouabain-insensitive respiration was highest during late lactation and the non-lactating period. It was concluded that Na+, K+-ATPase accounted for a major proportion of the duodenal mucosa maintenance energy expenditure. The magnitude of this expenditure is not constant throughout lactation. Key words: Na+, K+-ATPase, duodenal mucosa, O2 consumption, cows
GLUCOSE METABOLISM IN FAT AND THIN ADULT SHEEP
Authors: McNIVEN M. A.
Published: March 2010

The effect of body fatness on glucose metabolism was studied in six adult crossbred wethers divided into two groups weighing 90 kg (fat) or 55 kg (thin). Glucose turnover measurements were made using 6-3H-glucose by single injection at four levels of metabolizable energy intake: high, 17 MJ/day; intermediate, 10 MJ/day; low, 6 MJ/day; and fasting for both thin and fat groups. The greatest group differences occurred at the high feeding level. Body pool size and glucose space were significantly lower (P < 0.001) for the fat sheep and were reduced at fasting for both fatness levels. The mean irreversible loss rate was not affected by body fatness but was significantly affected (P < 0.001) by feeding level. Glucose recycled as a proportion of total entry rate was significantly affected by body fatness and was dependent on a positive or negative energy balance. When in negative energy balance the sheep maintained blood glucose within the normal range by recycling up to four times more glucose than was utilized. It appears that rate of glucose synthesis is related to energy balance and metabolizable energy intake. A tendency toward insulin insensitivity in the fat sheep could be related to high levels of recycling, and a greater glucose drain or prolonged fast could be more serious with the decreased glucose pool size and space. Key words: Glucose metabolism, ruminant, obese, energy balance