Strategies to alleviate heat stress on performance and physiological parameters in feedlot-finished cattle under heat stress conditions. A systematic review-meta-analysis.

Strategies to alleviate heat stress on live performance - dry matter intake (DMI), average daily gain (ADG), and feed conversion efficiency (FCE) - and on physiological parameters - respiratory rate (RR) and panting score (PS) - of feedlot-finished cattle were evaluated by systematic review-meta-analysis. Using the PICO framework were identified 3813 records, with 31 publications and 6729 cattle being considered in the meta-analysis (MA). The comparison most reported was sun vs. shade (n = 24 publications), followed by shade vs. shade (area per animal and effectivity in reduce solar load) (n = 7 publications) and sun vs. sprinkling (n = 4 publications). Cattle with access to shade with total reduction in solar load improved ADG (p = 0.008) and FCE (p = 0.024), and reduced RR (p < 0.001) compared to unshaded animals. Cattle with access to shade with a height between 3 and 4 m increased ADG (p < 0.001), tended to improve FCE (p = 0.054), and reduced RR (p < 0.001) compared to unshaded animals. An area of shade from 2 to 4 m2/animal increased ADG (p = 0.002), and higher than 4 m2/animal reduced RR (p < 0.001) compared to unshaded animals. Animals that received sprinkling volume below 1 L/animal/min improved ADG (p = 0.008) compared to unshaded animals. Cattle with access to shade with a high area per animal improved DMI (p = 0.023) and ADG (p < 0.001) compared to animals with a low area. In univariate meta-regression, it was observed that the variables significantly (P < 0.05) influencing DMI were THI category; influencing ADG were cattle gender, THI category, and coat color; influencing FCE were cattle age and hemisphere; and influencing RR were country, THI category and climate. Performance and physiological parameters of feedlot-finished cattle under heat stress depend on animal and environmental characteristics.

Beef Steers and Enteric Methane: Reducing Emissions by Managing Forage Diet Fiber Content.

Understanding the methane (CH4) emissions that are produced by enteric fermentation is one of the main problems to be solved for livestock, due to their GHG effects. These emissions are affected by the quantity and quality of their diets, thus, it is key to accurately define the intake and fiber content (NDF) of these forage diets. On the other hand, different emission prediction equations have been developed; however, there are scarce and uncertain results regarding their evaluation of the emissions that have been observed in forage diets. Therefore, the objectives of this study were to evaluate the effect of the NDF content of a forage diet on CH4 enteric emissions, and to evaluate the ability of models to predict the emissions from the animals that are consuming these forage diets. In total, thirty-six Angus steers (x¯ = 437 kg live weight) aged 18 months, blocked by live weight and placed in three automated feeding pens, were used to measure the enteric CH4. The animals were randomly assigned to two forage diets (n = 18), with moderate (<50%, MF) and high (>50%, HF) NDF contents. Their dry matter intake was recorded individually, and the CH4 emissions were measured using the SF6 tracer gas technique. For the model evaluation, six prediction equations were compared with 29 studies (n = 97 observations), analyzing the accuracy and precision of their estimates. The emission intensities per unit of DMI, per ADG, and per gross energy intake were significantly lower (p < 0.05) in the animals consuming the MF diet than in the animals consuming the HF diet (21.7 vs. 23.7 g CH4/kg DMI, 342 vs. 660 g CH4/kg ADG, and 6.7% vs. 7.5%, respectively), but there were no differences in the absolute emissions (p > 0.05). The best performing model was the IPCC 2006 model (r2 = 0.7, RMSE = 74.04). These results show that reducing the NDF content of a forage diet by at least 10% (52 g/kg DM) reduces the intensity of the g CH4/kg DMI by up to 8%, and that of the g CH4/kg ADG by almost half. The use of the IPCC 2006 model is suitable for estimating the CH4 emissions from animals consuming forage-based diets.

Effect of Fresh Citrus Pulp Supplementation on Animal Performance and Meat Quality of Feedlot Steers.

The use of fruit by-products such as citrus pulp represents a feeding ingredient that deserves to be evaluated as an energy source in animal rations. Thirty-six British breed steers were allotted to one of the three feeding treatments (12 steers/treatment): 0%, 15% and 30% of fresh citrus pulp inclusion in the ration in a randomized complete block design to evaluate animal performance and carcass and meat quality traits. In the present study, the inclusion of fresh citrus pulp up to 30% of the diet did not affect the animal average daily gain (p > 0.05) but steers that were fed the pulp consumed less feed (p < 0.05) and presented a lower feed conversion ratio (p < 0.05) than their counterparts without citrus pulp in their diet. No effect of fresh citrus pulp was observed on carcass and meat quality (p > 0.05). A greater lipophilic antioxidant capacity (p < 0.05) in meat was observed when fresh citrus pulp was offered at 15% of the diet. Fresh citrus pulp used up to 30% as a feed ingredient in feedlot rations does not negatively affect animal performance or meat quality but, rather, has a positive effect on dry matter intake and a better feed conversion ratio.

Effect of pre-slaughter fasting duration on physiology, carcass and meat quality in beef cattle finished on pastures or feedlot.

Pre-slaughter fasting duration affect blood parameters related to stress and metabolism, decrease live and carcass weights and impact beef quality of cattle. In three experiments, 1100 steers and heifers, finished on feedlot or on pasture, were evaluated to assess the influence of the site and duration of fasting before slaughter on physiological, carcass and meat quality traits. Cattle were allocated to one of two fasting duration - long (23-29 h) or short (2-6 h) - and to one of two sites of fasting- farm or abattoir. All animals had access to water ad libitum until slaughter, except during transportation. Cattle were assigned to two (long fasting on abattoir/normal lairage time, short fasting on farm/minimal lairage time) or three (long fasting on abattoir/normal lairage time, short fasting on farm/minimal lairage time, long fasting on farm/minimal lairage time) treatments. Seventeen slaughters were considered in a randomized complete block design. There was no effect of the site of fasting on any variable. Cattle with short fasting duration had higher carcass weights and water consumption than those under long fasting duration. Haematocrit, globulin, total protein, and lactate dehydrogenase at the time of slaughter increased with fasting duration. There was no effect of the duration of fasting on blood ions, meat quality traits, urine pH, liver weight and volume, and skin dry matter. A reduction in the fasting duration returned to farmers and abattoirs 1.2% additional kilograms of carcass, suggesting an improvement in animal welfare according to a better hydration level of cattle at the time of slaughter.

Acute and chronic bovine pulmonary edema and emphysema in Uruguay / Edema e enfisema pulmonar agudo e crônico em bovinos do Uruguai

An outbreak of pulmonary edema and emphysema with acute and chronic cases is reported in a farm in Uruguay. In a herd of 40 Hereford steers, 20 died. The deaths began four days after a change of paddock, from an old pasture of Avena sativa to a lush growing pasture of the same grass. Acutely affected animals showed severe dyspnea, sialorrhea, cough, and subcutaneous edema, and died within 72 hours. Chronically affected steers showed dyspnea, respiratory noises, weight loss, and intolerance to exercise. The deaths began four days after the change of paddock. Ten days after the first death, the steers were withdrawn from the pasture, but continued dying throughout the following 40 days. Twenty animals died and six were necropsied. Grossly, the lungs were diffusely armed and glistening, with reddish and crepitant cut surface, and presented alveolar septae sharply distended by edema and emphysema. There was subpleural emphysema with air blebs distributed across the pleural surface. Presence of Dictyocaulus viviparus was observed in three steers. In some animals, the trachea was diffusely reddish with presence of pink foam; in some others, there was bloody liquid in the tracheal lumen. Histologic examination showed severe diffuse alveolar and interstitial emphysema, hyaline membranes adhered to the alveolar wall, thickening of the interlobular septae with proliferation of type II pneumocytes, and moderate-to-severe multifocal histiocytic, neutrophilic and eosinophilic infiltrate. In the trachea, there was submucosal hemorrhage and moderate multifocal eosinophilic and lymphocytic infiltrate. The steers with chronic signs presented similar lung lesions, but multifocal pulmonary fibrosis and cardiac dilatation were also observed. The diagnosis of acute bovine pulmonary emphysema and edema (ABPE) was based on the occurrence of the disease after introduction of the herd in a lush green pasture, on the characteristic gross and histologic lesions, and on the absence of other toxic or infectious agents causing similar lesions. Cattle raisers should be alert to the risks of occurrence of this disease after the introduction of the herds into paddocks with green and lush pastures.(AU)

Descreve-se um surto de edema e enfisema pulmonar com casos agudos e crônicos em bovinos em uma criação semi-intensiva no Uruguai. De um lote de 40 novilhos da raça Hereford morreram 20. As mortes começaram quatro dias após uma mudança de alimentação, de uma pastagem mais velha de Avena sativa, para uma pastagem recentemente plantada de aveia que estava em brotação. Os animais afetados apresentaram sinais clínicos agudos de dispneia, sialorreia, tosse e alguns desenvolveram edema subcutâneo, morrendo em até 72 horas. Outros novilhos mais cronicamente afetados apresentaram dispneia, ruídos respiratórios, perda de peso e intolerância ao exercício. As mortes começaram quatro dias após a mudança de pastagens. Dez dias após a primeira morte, os novilhos foram retirados do pasto, mas morreram ainda durante 40 dias mais. Ao total, morreram vinte animais e seis foram necropsiados. Nas necropsias dos animais mortos na fase aguda os pulmões estavam difusamente armados e brilhosos e ao corte de coloração avermelhada e crepitante, com os septos alveolares acentuadamente distendidos por edema e enfisema. Havia enfisema subpleural caracterizado por bolhas de ar distribuídas pela superfície pleural. Em três bovinos havia ainda presença de Dictyocaulus viviparus. Alguns animais apresentaram a traqueia difusamente avermelhada com espuma de coloração rósea ou liquido sanguinolento livre na luz traqueal. Histologicamente havia edema e enfisema alveolar e intersticial difuso severo, membranas hialinas espessas aderidas à parede alveolar, espessamento dos septos interlobulares com proliferação de pneumócitos tipo II e infiltrado inflamatório histiocítico, neutrofílico e eosinofílico multifocal moderado a severo. Na traqueia havia hemorragias na submucosa e infiltrado eosinofílico e linfocítico multifocal. Os novilhos com sinais crônicos apresentaram lesões pulmonares semelhantes, entretanto, foram observadas também, fibrose pulmonar multifocal e dilatação cardíaca. O diagnóstico de EEPAB baseou-se na ocorrência da doença após a introdução do rebanho em uma pastagem viçosa em brotação, nas características macroscópicas e histológicas e na ausência de outros agentes tóxicos ou infecciosos que causam lesões semelhantes. Se alerta para os riscos da ocorrência desta enfermidade, quando houver mudanças de pastagens.(AU)