AN ALTERNATIVE METHOD FOR ANALYZING FORAGE/LIVESTOCK SYSTEMS

A mixed integer program solves for profit-maximizing forage and beef enterprises. Dry matter, total digestible nutrients, and crude protein characterize livestock nutritional needs and production of warm and cool season forages.Livestock Production/Industries,

Economic Value of Improving Feed Efficiency of Beef Cows on Pasture

Dry matter intake of beef cows is based on a percentage of body weight, so as mature cow size increases, intake increases. Feed efficiency, or the amount of feed required to produce gain or maintain production, has a direct impact to the producer. That is, as mature cow weight increases, yearly maintenance costs increases due to higher feed costs. However, variation in feed efficiency exists within population. Some large cows consume the same or less dry matter as a smaller cow, but produce a larger calf. Conversly, some smaller cows consume the same or more as a large cow but produce a smaller calf. Cows identified to have improved feed efficiency should have an economic advantage to producers, primarily due to improvements in stocking rates. To determine this value, we utilized data reflecting individual animal measures of cow body weight, feed intake and calf weaning weights from a trial using multiparous Angus mature cows ranging in initial weight from 513 kg to 731 kg. An economic benefit-cost model was used to determine net returns of feed efficiency for six cow-calf production systems reflecting combinations of three levels of intake efficiencies and two forage species. Production systems grazing either bermudagrass or native prairie grass pastures with 50 and 75 percent improvements in dry matter intake realized 17 and 28 percent higher stocking rates (hd ha-1) relative to conventional systems with an average mix of dry matter intake. Due to higher stocking rates, costs associated with pasture maintenance, feed, healthcare, breeding and operating interest were greater for the more efficient systems. However, the additional revenue from marketing additional kilograms of weaned calves was greater than the increase in costs. Net returns for improved herd feed efficiency ranged from $32-195 ha-1. Selection for feed efficiency in beef cows has positive net returns to producers

Effect of COD: SO42- Ratio, HRT and Linoleic Acid Concentration on Mesophilic Sulfate Reduction: Reactor Performance and Microbial Population Dynamics

Biological sulfate (SO42-) reduction was examined in anaerobic sequential batch reactors (ASBRs) operated under different hydraulic retention times (HRTs) ranging from 12 to 36 h and COD (Chemical Oxygen Demand)/SO42- ratios of 2.4, 1.6 and 0.8. Competition between SO42- reducing bacteria (SRBs), methane producing archaea (MPAs) and homoacetogens (HACs) was examined in controls and cultures treated with linoleic acid (LA). The ASBR performance was influenced by the COD/SO42- ratio in control cultures with a SO42- reduction of 87% at a COD/SO42- ratio of 0.8. At a 12 h HRT, in both control and LA treated cultures, greater than 75% SO42- removal was observed under all the conditions examined. In control reactors operating at a 36 h HRT, high levels of MPAs belonging to Methanobacteriales and Methanosarcinales were detected; however, in comparison, under low COD/SO42- ratio and with decreasing HRT conditions, a relative increase in SRBs belonging to Desulfovibrio and Desulfatibacillum was observed. Adding 0.5 gL(-1) LA suppressed Methanobacteriales, while increasing the LA concentration to 1 gL(-1) completely suppressed MPAs with a relative increase in SRBs. HACs belonging to Bacteroidetes were observed in the control and in cultures operated at 12 h HRT with a COD/SO42- ratio of 1.6 and fed 0.5 gL(-1) LA; however, with all other LA levels (0.5 and 1.0 gL(-1)) and HRTs (12, 24 and 36 h), HACs were not detected

Buyer preferences for feeder calf traits

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Knowledge, attitudes, and practices regarding ticks, tick-borne pathogens, and tick prevention among beef producers in Oklahoma

Tick-borne diseases are increasing in the United States, with regional need to understand how knowledge of ticks translates into preventative behavior among specific occupational groups. Little is known regarding what livestock producers know about ticks and their perceived personal and herd-based risk despite being one of the largest agro-industries in the United States. Using a nonprobability convenience sampling protocol, 183 beef producers representing 65% of the counties in Oklahoma completed a 15-question survey focused on knowledge of ticks and perceived risks ticks pose to their cattle and themselves, their methods of prevention (personal and their cattle), and sources of information. Most producers thought ticks were not a major problem for their cattle (58%), themselves, their families, and those who worked for them (66%). Most were personally concerned about spotted fever group rickettsiosis (79%) but had never heard of ehrlichiosis (9%). Eighty-five percent used at least one type of personal protective behavior, and 86% used at least one source of information for issues with ticks on their cattle. As the first published tick-focused survey involving livestock producers in the United States, it is apparent that beef producers in the central region are cognizant of ticks on their cattle and perceive ticks to be a risk on some level. However, increasing their knowledge of all areas of ticks and tick-borne pathogens, especially preventative measures for humans and cattle, is needed.Peer reviewedEntomology and Plant PathologyAnimal and Food Science

Vitamin E supplementation of newly arrived feedlot calves

Seven hundred fifteen crossbred (primarily British) calves purchased in southern Oklahoma and northern Texas auction barns were received at the Willard Sparks Beef Research Center, Stillwater, OK, and used to study effects of duration (days) of vitamin E feeding during a 42-d receiving period on animal performance, health, and serum cholesterol and vitamin E concentrations. Upon arrival, calves were blocked by load (seven loads), sorted by BW (light, n = 4 pens per load; and heavy, n = 4 pens per load), and assigned randomly to one of four dietary treatments (n = 2 pens per load; 14 pens per treatment). Experimental diets were formulated to provide 2,000 IU calf^-1 d^-1 of supplemental vitamin E (DL-alpha-tocopherol acetate) for 0 (CON), 7 (E7), 14 (E14), or 28 (E28) d. Vitamin E was delivered in a pelleted supplement that was added to the basal diet in decreasing concentrations as DMI increased (2.0 kg of DMI = 6%; 4.0 kg of DMI = 4%; and 6.0 kg of DMI = 2%). Serum samples were collected on d 0, 14, 28, and 42 for determination of cholesterol, alpha-tocopherol (d 0, 28, and 42), and antibody (IgG) concentrations. Duration of vitamin E supplementation did not affect ADG (0.98 kg/d; P = 0.56) or G:F (0.189; P = 0.87). Serum cholesterol concentrations decreased (day effect; P < 0.001) for all treatments from d 0 (average = 127 mg/100 mL) to 14 (average = 62 mg/100 mL). Serum alpha-tocopherol decreased (day effect; P < 0.001) from d 0 (5.2 micro-g/mL) to 28 (1.8 micro-g/mL); however, on d 28, a greater (P < 0.001) serum alpha-tocopherol concentration was observed for E28 (3.4 micro-g/mL) calves than for CON (1.1 micro-g/mL), E7 (1.2 micro-g/mL), or E14 (1.5 micro-g/mL) calves. Respiratory disease was diagnosed in 64.6% of calves in this study. Medical costs were less (P = 0.08) for calves fed vitamin E for 28 d ($4.88/calf) than for calves fed the control diet ($6.29/calf). Carcass characteristics were not affected (P = 0.19 to 0.88) by dietary treatments. Supplemental vitamin E formulated for 2,000 IU calf^-1 d^-1 had little influence on performance and overall health status of calves under our experimental conditions; however, the increased serum concentrations of alpha-tocopherol when vitamin E was fed for 28 d suggests that any potential effects of vitamin E on health status might be time-dependent.Peer reviewedAnimal ScienceVeterinary PathobiologyVeterinary Medicine OutreachStatistic

Body condition score, weight variation and reproductive performance of beef cows in rangelands from the Pantanal region

Objetivou-se avaliar a influência do escore de condição corporal (ECC) sobre a eficiência reprodutiva de vacas de cria nos períodos pré e pós-parto e a probabilidade de parição, usando o escore de condição corporal e a variação ponderal no período crítico do ciclo reprodutivo. Utilizaram-se 248 vacas multíparas mantidas em pastagens nativas distribuídas em quatro estratégias de suplementação: mistura mineral (controle); suplemento farelado; suplemento líquido; suplemento líquido para vacas e bezerros. As avaliações de peso e ECC, na escala de 1 a 9, foram realizadas no período crítico: em agosto (período pré-parto, 60-90 dias antes da parição) e em janeiro (período pós-parto e reprodutivo) durante quatro anos consecutivos. Para a análise dos anos consecutivos de reprodução, criou-se um escore de reprodução, ou seja, somou-se o número de parições de cada vaca durante os quatro anos pecuários avaliados. O escore de condição corporal nos períodos pré e pós-parto e a idade da vaca influenciaram o escore de reprodução. Portanto, para avaliação da probabilidade de parição, foram utilizadas todas as vacas, classificadas em paridas e vazias. Utilizando equações de estimação generalizadas (EEG), foi modelada a probabilidade de as matrizes serem classificadas como paridas considerando variáveis exploratórias ao longo do tempo. Para se obter probabilidade de parição superior a 80%, as vacas devem possuir escore de aproximadamente 5,5 no período pré-parto. Aproximadamente 60% das vacas paridas mantiveram ou ganharam peso no período crítico do ano, o que levou a maior probabilidade de reconcepção, similar ao observado para as vacas vazias, porém com probabilidade menor de parição. O período pré-parto é o melhor para estimar a probabilidade de parição das vacas por meio da avaliação do escore corporal. A seleção de vacas adaptadas às condições bioclimáticas do Pantanal aumenta a probabilidade de produção de um bezerro por vaca por ano. _________________________________________________________________________________ ABSTRACTThe aim of this study was to evaluate the influence of body condition score (BCS) on reproductive performance of beef cows before and after calving and to evaluate the calving probability using body condition score and weight variation during critical periods of the cow reproductive cycle. From 2001 to 2005, the body condition score was recorded in 248 multiparous cows raised in native pastures, submitted to different supplementation treatments (mineral mixture only - control; dry supplement; liquid supplement and liquid supplement for cow and calves). Weighing and body condition evaluation were made on a 1-9 point scale in August (prepartum period, 60-90 days before parturition) and January (postpartum and reproductive period). A reproduction score was created in function of the body scores in four consecutive years. Except for the treatment, the other factors (body condition score in the prepartum and postpartum periods and cow age) influenced the reproduction score. Thus, the calving probabilities were estimated for all cows. Generalized estimating equations (GEE) were used to evaluate the calving probability in function of the exploratory variables over time. Calving probability higher than 80% was obtained when cows scored 5,5 before calving. In relation to weight, the results showed that about 60% of calving cows maintained or gained weight in the postpartum period, leading to increase in the rebreeding probability. Similar situation occurred with single cows; however, the calving probability was lower. These results indicate that the calving probability using BCS is better estimated before calving. Furthermore, it indicates the presence of cows more adapted to the Pantanal climatic and feeding conditions than others