Mechanical and hand catching of broilers were performed to determine if differences existed in breast meat quality among catching methods. Meat quality results were summarized using a two-prong approach to investigate if average differences existed in meat quality through the determination of ultimate pH, rapid pH decline, color, water holding capacity, and tenderness within each treatment and by pinpointing individual quality problems within treatments. Two trials were conducted and revealed greater variation in meat quality during summer in comparison to winter within treatments in both catching methods. In winter, there was a lower incidence (p<0.05) of paleness in birds that were crated for 2h prior to euthanasia in comparison to birds immediately euthanized after catching within both hand and machine catching methods. Mechanical catching and crating for 2 hours was conducive to slightly better quality meat than hand catching in respect to averages and individual quality problems.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1978 G94 / Master of Science

Call number: LD2668 .T4 1979 H39 / Master of Science

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

En la present tesis s'han estudiat estratègies per incrementar l'eficiència de la producció intensiva de vedells mitjançant pràctiques de maneig i d'alimentació. La primera estratègia plantejada per augmentar l'eficiència de la producció intensiva de vedells ha estat la millora de la qualitat de la canal i la carn. Per aquesta raó, es va desenvolupar un estudi per avaluar els efectes de diferents factors pre-sacrifici sobre la incidència de carns amb pH alt o canals amb danys tissulars extrems, i per aconseguir propostes i decisions tècniques de maneig per disminuir la incidència de carns amb pH alt o canals amb danys tissulars extrems. Desafortunadament, l'objectiu per se no es va assolir perquè la variablititat del pH últim de la carn i la incidència de canals amb dany tissular extrem explicada per aquests factors va ser molt baixa. Conseqüentment, la indústria càrnia ha d'acceptar com a "normal" un percentatge de canals amb pH elevat (per sobre 13%) i/o presència de dany tissular extrem (per sobre 2%). La castració pre-pubertal-l de vedells Holstein (8 mesos d'edat) mitjançant Burdizzo també s'ha estudiat com a pràctica de maneig per millorar la qualitat de la canal i la carn. De fet, els resultats d'aquest estudi demostren que la castració millora la classificació d'engreixament de la canal, el contingut de greix intramuscular, el valor dels paràmetres colorimètrics, i la tendresa. A més a més, l'assoliment d'una tendresa òptima en els animals castrats sense pràcticament temps de maduració, representa una avantatge competitiva en la indústria espanyola de la carn. No obstant, la castració mitjançant el mètode Burdizzo pot fallar en un 23% dels casos, i reduir el guany de pes total durant la fase d'acabat. A més a més, la castració il·lustra la delicada situació relacionada amb temes de benestar animal i pràctiques de maneig a la granja, per tant, més investigació relacionada amb els efectes de la castració sobre el dolor crònic i agut i l'estrès és necessària per assegurar que és una bona estratègia per augmentar la qualitat de la carn i la canal de vedells Holstein. Finalment, la suplementació en les dietes dels vedells amb ingredients rics en omega-3 també s'ha proposat com a estratègia per augmentar la qualitat de la canal i la carn. Efectivament, la suplementació a les dietes amb llavor de lli per sobre el 12% en el total de matèria seca ingerida, augmenta la qualitat de la carn, i a més converteix la carn en un producte funcional (carn enriquida amb omega-3), sense afectar la producció animal i la fermentació ruminal. La oportunitat d'expansió en el mercat sembla favorable i l'interès dels consumidors és elevat, però la difusió d'aquest productes necessita de la superació de la legislació per a la certificació, així com el preu elevat de les llavors de lli i la seva disponibilitat. La segona alternativa plantejada per augmentar l'eficiència de la producció intensiva de vedells ha estat la reducció dels costos d'alimentació a través de la utilització de sub-productes de la indústria. Per aquesta raó, s'ha proposat estudiar els efectes de l'inclusió de glicerina per sobre el 12% en el total de matèria seca ingerida, com a ingredient energètic alternatiu als cereals. Amb èxit, la inclusió de glicerina com a ingredient energètic no ha afectat negativament els índexs de producció animal, la fermentació ruminal, el metabolisme, i els paràmetres de qualitat de la canal i la carn. No obstant, avui en dia, la reducció dels costos d'alimentació a través de la inclusió de glicerina pot no ser una bona estratègia degut al seu alt cost en relació als altres ingredients.En resum, la present tesis no només ha proporcionat resultats sobre diferents estratègies de maneig i alimentació que milloren la eficiència de producció intensiva, sinó també informació sobre les seves limitacions i inconvenients. / In the present thesis, strategies to increase efficiency in intensive beef production focused mainly on feeding and management practices have been studied. The first strategy proposed to increase the efficiency of intensive beef production has been the improvement of carcass and meat quality. Indeed, a study was conducted to evaluate the effect of different pre-slaughter factors on the incidence of high ultimate pH and extreme carcass bruises, and to make proposals pertaining to management, technical, or economic decisions, which could lead to improvements on the high incidence of high ultimate meat pH and the extreme carcass bruises observed in intensive beef production systems. Unfortunately the objective per se was not achieved because the variability of ultimate meat pH and carcass bruises explained by these factors was very low. In consequence, the percentage of beef carcasses with high ultimate meat pH (up to 13%) and extreme bruises (up to 2%) needs to be accepted as "normal" by the current beef industry. Burdizzo castration of pre-pubertal (8 months of age) Holstein bulls has also been studied as an animal management practice, in order to improve carcass and meat quality. For instance, results from this study stated that castration improves the grade of backfat classification, the intramuscular fat content, colorimetric parameters, and tenderness. Furthermore, as the optimal tenderness might be achieved in castrated animals without a long ageing period, it represents a good competitive advantage for the Spanish beef industry. However, Burdizzo castration might fail in 23% of the cases, and might reduce the total weight gain during the finishing phase. Additionally, the practice of castration illustrates the delicate balance between animal welfare and some management practices on the farm. Therefore, further research (specially in acute and chronic pain and stress) will be necessary to ensure that castration is a good method of improving the meat quality in Holstein bulls. Finally, the supplementation of specific omega-3 rich-ingredients in the ruminant diets has also been proposed as a strategy to increase the carcass and meat quality. Effectively, the supplementation of whole linseed of up to 12% of total dry matter intake, enhances meat quality, and additionally converts meat into functional food (meat rich in omega-3), without affecting animal performance and rumen fermentation. The opportunities for expansion of the market seem to be quite favourable and the interest of the consumers is quite high, but the diffusion of these products in the community area is slowed down by some obstacles, including certification, the prices of whole linseed, and its availability.The second strategy proposed to increase the efficiency of intensive beef production has been the reduction of feeding cost through the use of industrial by-products. Indeed, the study of the effect of the inclusion of crude glycerin up to 10% of total dry matter intake, as an alternative energy source, to substitute cereals in the diet, has been proposed. Fortunately, the inclusion of crude glycerin of up to 12.1%, does not incur any negative effects in performance, ruminal fermentation, metabolism, animal health, or carcass and meat quality parameters. However, today the reduction of feeding cost through the inclusion of crude glycerin may not be a feasible strategy as a result of the high price of crude glycerin in relation to other concentrate ingredients.In summary, the present thesis not only provides the results of different feeding and management strategies to improve intensive beef production efficiency, but also highlights concerns about their constrains and limitations.

Correlations between cattle disposition and meat quality were expected to be found, as well as differences in meat quality traits among contemporary groups, sires, and families nested within sires. Temperament effects on meat quality were evaluated in Nellore × Angus F2 cross cattle (n = 238) over a 3-yr period, with harvests twice a year. Five aspects of temperament -- aggressiveness, nervousness, flightiness, gregariousness, and overall temperament -- were evaluated at weaning and yearling ages, as well as an overall temperament score at slaughter. USDA quality grade, fat thickness, adjusted fat thickness, hot carcass weight, USDA yield grade, and chemical fat were correlated negatively (P < 0.05) with weaning temperament scores, aggressiveness, nervousness, flightiness, gregariousness, and overall temperament. No significant correlation was found between Warner-Bratzler shear and weaning temperament traits. USDA quality grade and live weight were correlated negatively (P < 0.05) with yearling temperament scores, nervousness, flightiness, gregariousness, overall temperament score as well as the temperament score observed at slaughter. Fat thickness and adjusted fat thickness also were correlated negatively (P < 0.05) with yearling gregariousness, yearling overall, and slaughter overall temperament. Yearling gregariousness was correlated positively (P < 0.05) with Warner-Bratzler shear from both ES and NON carcasses. Least squares mean differences were evaluated among contemporary groups, sires, and families nested within sires for overall temperament traits and meat quality traits. Contemporary group differences found were thought to be explained by environmental factors, as seen in contemporary group 5, which had the smallest ribeye possibly caused by the shortest feeding period. Steers sired by 297J had the lowest (calmest) temperament scores, most 12th rib fat, highest numerical yield grade, and the heaviest weights. Sire 437J had steers with the highest (wildest) temperament scores, the least fat and lowest numerical yield grade. This population was designed to identify QTL for economically important traits and appears to be useful for this purpose because of the differences found both between and within families.

Temperament effects on meat quality were investigated using three contemporary groups consisting of Bonsmara-sired yearling-fed (n = 31), Angus-sired calf-fed (n = 49), and Angus-sired yearling-fed (n = 48) steers. To evaluate temperament, exit velocity, pen scores, and chute scores were determined before shipment to the feedlot, and exit velocity was measured on arrival to the feedlot and after approximately 70 d on feed. Serum cortisol concentration was determined at each evaluation and before slaughter. At slaughter, pH and temperature were monitored in the M. longissimus lumborum. USDA yield and quality grade factors and CIE color space values were determined, and M. longissimus lumborum steaks were evaluated for sarcomere length, 72-h calpastatin activity, proximate composition, and Warner-Bratzler shear force (WBS) values 3, 7, 14, and 21 d postmortem. Temperament categories were based on rankings within contemporary groups at each evaluation. Temperament traits were consistent across evaluations, and values decreased (P < 0.05) in magnitude over time. Relationships between temperament traits were consistent across contemporary groups. Increasing excitability was associated with higher (P < 0.05) serum cortisol concentration. Body weight was slightly lower (P < 0.05) in cattle with excitable temperaments at all evaluations. Carcass characteristics, proximate composition, muscle color, and calpastatin activity were unaffected by temperament. Carcasses from cattle with calm temperaments had higher 0.5 h postmortem pH values than those from intermediate and excitable cattle (0.1 and 0.2 units, respectively). The Angus-sired yearling-fed steers classified as Excitable had higher (P < 0.05) WBS values than the calmer Angus-sired, yearling-fed steers. This trend was observed in the Bonsmara-sired steers, although the values were not statistically different. No differences attributable to temperament were apparent in the Angus-sired calf-fed steers. Correlations were highest between temperament values and tenderness after 21 d. Yearling-fed cattle classified as Excitable before shipment to the feedlot produced tougher (P < 0.05) steaks than those from calmer animals. At evaluations later in production, Calm steers produced tougher (P < 0.05) steaks. Tenderness did not differ across temperament categories in calf-fed steers regardless of sorting time. These data indicate temperament influences tenderness, though the mechanism is not clear.