NUTRITION AND MANAGEMENT STRATEGIES TO IMPROVE HEALTH AND MEAT QUALITY OF INTENSIVELY REARED RUMINANTS
Creators: name: BALDI, GIANLUCA
Publisher: name: Universit� degli Studi di Milano
Year: 2015

description: Nowadays meat quality perception is multifactorial and, especially for red meat, consumers are becoming more and more critics about sensory traits and concerned about psychological and ethical aspects, such as sustainability, animal welfare, antibiotics utilization, safety and healthiness. Address to these topics is fundamental for red meat industry, in order to counteract the decreasing consumption in western countries and to improve production efficiency to fulfill the growing demand from developing countries. Improving all the aspects related to perceived quality will lead to meet consumer satisfaction, with positive impact on demand, and to increase production efficiency and profitability. The following trials aimed to evaluate specific dietary supplements and on farm and post farm strategies to improve animal health, strictly connected with sustainability, animal welfare and production efficiency, and meat appearance and eating quality. 8.1. Trial 1 Bovine respiratory disease (BRD) represents a concern for veal industry, as it causes economic losses, reduces animal welfare and increases antibiotics utilization. A field study to evaluate the effects of multivalent vaccination on veal calves? health and performance was carried out. 944 healthy calves were randomly allotted into two separate barns. One group was vaccinated 7 days after arrival with quadrivalent vaccine against IBR, PI3, BRSV and BVDV Type 1 viruses plus booster administration 21 days apart (VAC; 675 calves), while the second group was not treated (CON; 269 calves). Vaccination did not affect overall mortality (P=0.75) and mortality due to BRD (P=0.28), while it reduced BRD morbidity (P=0.009). VAC group showed better average daily gain (ADG; P=0.03) and carcass weight (P&lt;0.001). Vaccination delayed the peak of BRD by nearly two weeks (P&lt;0.001) and represented a protective factor against BRD (OR 0.55; P=0.001). BRD increased mortality (P=0.01), lowered ADG (P&lt;0.001) and carcass weight (P&lt;0.001), increased the amount of discounted carcasses (P&lt;0.001). Lung lesions and pleuritis and/or consolidations increased with BRD (P=&lt;0.001) but were unaffected by vaccination (P=0.40 and P=0.43 respectively). In conclusion, BRD impaired veal calves? health, growth and carcass value and vaccination reduced BRD morbidity, thus improving carcass value. 8.2. Trial 2 Selenium (Se) is involved in several biological functions and its supplementation is necessary for farm animals. Se can be provided in organic or inorganic forms, the former characterized by a higher bioavailability. Despite organic supplementation generally increased the meat Se, inconsistencies in the effects on meat quality have been reported and only one short?term supplementation study has been performed. The study aimed to compare the effects of switching the Se source in the last 60 days of fattening on growth performance, beef quality and Se content. Charolaise beef heifers supplemented since the beginning of the fattening period with sodium selenite (162 heads; 517�61 days of age) were divided into two groups, fed the same diet, in which Se (0.2 mg Se/kg DM of feed) was provided as sodium selenite (SS; 82 heads, 450.36�33.69 kg BW) or selenium-enriched yeast (Se-Y; 80 heads, 454.60�41.70 kg BW). Live weight was measured at the beginning and at the end of the trial and meat samples were collected from 30 homogeneous carcasses/group 48 hours post mortem to evaluate centesimal composition, Se content, shear force and cooking loss. Colour, pH, water holding capacity and appearance were evaluated daily for 8 consecutive days of aerobic storage. The Se source did not affect growth performance, meat centesimal composition, thawing loss, cooking and drip loss and pH during 8 days of aerobic storage. Se-Y supplementation improved the meat Se content (P&lt;0.001) and tended to reduce shear force (P=0.076). Lightness (P&lt;0.01) and yellowness (P&lt;0.01) decreased with the duration of storage and were higher in the Se-Y group compared with the SS group. Meat from group Se-Y also showed a better visual score for color (P&lt;0.01), odor (P&lt;0.05), surface wetness (P&lt;0.05), and overall appearance (P&lt;0.01). Under the presented experimental conditions, switching selenium supplementation from sodium selenite to selenium-enriched yeast during the last two months of fattening did not affect heifer performance or meat water holding capacity, but improved meat tenderness and color stability during storage, with a positive impact on meat shelf life. The present study also confirmed that short-term supplementation represents a valid strategy for increasing meat Se content. 8.3. Trial 3 Inadequate concentration of vitamin E affect retail color and oxidative stability. Vitamin E (VitE) can be supplemented as synthetic all-rac ?-tocopheryl acetate or through antioxidant-rich feed as lucerne. The study compared the effects of feeding lambs with a grain based diet at moderate (MOD 42 mg?kg-1 VitE E as all-rac ?-tocopheryl acetate) or supranutritional (SUP 285 mg?kg-1 of vitamin E all-rac ?-tocopheryl acetate) levels of vitamin E and organic selenium or a lucerne based diet (LUC; 37 mg?kg-1 VitE) for 8 weeks before slaughter. Forty-eight lambs blocked by sex (wethers or females) and feed intake in the last three days of adaptation were randomly assigned to one of the three dietary treatments (16 lambs/treatment). Treatment did not affect DMI (P=0.46) and ADG (P=0.76). LUC group showed lower n-6 and PUFA compared to both MOD (P&lt;0.01) and SUP (P&lt;0.01). Despite a similar VitE intake, muscle vitamin E was higher for LUC compared to MOD (P&lt;0.05), while SUP fed animals showed the highest content (P&lt;0.01). Although that, fresh muscle from LUC showed a better a* stability during 4 days display time compared to MOD and SUP, while no differences were evident considering 6-weeks aged muscles. Oxidative stability measured with T-bars method, did not differ between groups at the beginning and at the end of display life for both fresh and aged muscles. Increasing dietary vitamin E in finishing lambs increased muscle vitamin E content. However, finishing lambs on Lucerne improved color stability of fresh lamb meat, compared to the artificial form. 8.4. Trial 4 Tenderness is one of the main factors affecting consumer preferences and consumers expect veal to be tender. Post mortem ageing improves meat tenderness but, since veal is not commonly aged in commercial practices, it is necessary to evaluate the effects of long-term chilling storage not only on meat tenderness, but also on the physical and sensory properties. The study evaluated the effects of vacuum ageing (2, 4, 6, 8, 10, 12, 16 days) on veal loin (longissimus dorsi; LD) and silverside (biceps femoris; BF) physical and sensory characteristics. Entire cuts were collected from 8 homogeneous carcasses and each divided into eight subsamples, vacuum packed and assigned to one of the seven different ageing treatments and the remaining one was used for chemical composition. Distribution has been done ensuring that each portion of the muscle was equally represented in each ageing time. LD was selected due to its economic significance, while BF is recognized as a less tender hindquarter beef cut when dry-heat cooked. Ageing did not affect cooking loss, increased LD pH and L*, a* and b* in both muscles. shear force (SF) decreased until day 6 in LD and day 10 in BF. Aroma, flavour and taste were not affected, while texture traits were improved. SF was negative correlated with tenderness and juiciness and positive correlated with BF fibrousness and stringy sensation. Postmortem ageing under vacuum conditions improved the instrumental and sensory tenderness without alteration of aroma, flavour, taste and juiciness measured after frozen storage and thawing. Ageing, coupled with freezing and thawing, did, however, reduce the oxidative stability in both muscles, without altering cooking loss and pH. The improvements in LD tenderness and related sensory traits occurred mainly during the first week of postmortem ageing, while in BF, effects were also evident until day 10. Under these experimental conditions, a minimum period of 4 days for LD muscle, and 8 days for BF muscle was necessary to obtain a clear tenderizing effect.