M. Chahine

Effect of preslaughter feeding and ractopamine hydrochloride supplementation on growth performance, carcass characteristics, and end product quality in market dairy cows

An experiment was conducted in market dairy cows to determine the effect of feeding time and ractopamine hydrochloride (RAC) on growth performance, carcass characteristics, and end product quality. In 3 replicates, 9 Holstein cows per replicate (n = 27; 659 +/- 25.3 kg initial BW) culled from 3 dairies were randomly assigned to 3 treatments: 1) slaughter immediately (control), 2) feed for 90 d (NoR), or 3) feed for 90 d with RAC (312 mg.cow(-1).d(-1)) for the final 32 d (RAC). On d 0, NoR and RAC cows were placed in individual pens and fed a high concentrate diet (86% concentrate, DM basis) for 90 d before slaughter. All cows were subjectively scored for BCS and locomotion score on d 0, and NoR and RAC cows were evaluated again after 90 d. Individual DMI was recorded daily throughout the trial, and BW was collected every 14 d. Age and age x treatment did not affect (P > 0.05) any of the traits evaluated in this study. When cows fed for 90 d (NoR and RAC combined) were compared with nonfed controls, fed cows had greater (P < 0.001) final BCS, BW and HCW, lower (P < 0.001) final locomotion score, and greater (P < 0.03) dressing percentage, external fat thickness, and marbling score. Fed cows also tended to have more desirable yield grade (P = 0.08), ribeye area (P = 0.11), fat color (P = 0.09), lean maturity (P = 0.06), and quality grade (P = 0.09) compared with control cows. Warner-Bratzler shear force was not affected (P = 0.23) by feeding. However, a 12-member trained sensory panel revealed that fed cow carcasses had more desirable (P < 0.04) tenderness, juiciness, and overall acceptability than control cow carcasses. Flavor intensity also tended (P = 0.10) to be more desirable for fed vs. control cows. No difference (P > 0.10) in off-flavor was detected among treatments. Finally, there was no effect (P > 0.10) of RAC on growth performance, carcass characteristics, or end product quality. In conclusion, feeding a high concentrate diet for 90 d improved important live animal, carcass, and end product characteristics related to the quality and palatability of beef from market dairy cows; however, no effect of RAC supplementation was observed.

Effects of dietary betaine on milk yield and milk composition of mid-lactation Holstein dairy cows

Betaine, naturally found in plants and an oxidative product of choline, is converted to acetate in the rumen, which may be used for milk fat synthesis. The objective of this study was to determine the effect of supplemental dietary betaine on milk yield and milk composition. Eighteen Holstein dairy cows (126±5 d in milk; mean ± SD) were randomly assigned to a sequence of treatments of rumen-unprotected betaine at 0, 25, 50, and 100 g/d added to a standard lactation ration in a 4×4 Latin square design. Animals were fed individually with feed intake and milk yield recorded daily. Body condition score and body weight were recorded on the last day of each period that lasted 16 d, with milk sampled on the last 2 d of each period. Milk composition was determined by a Dairy Herd Improvement Association laboratory and milk fatty acids were determined by gas chromatography. Data collected over the last 2 to 3 d were analyzed using the MIXED procedure in SAS (SAS Institute Inc., Cary, NC). Milk yield (mean ± SEM) was increased by betaine when fed at 100g/d (22.4, 22.5, 22.8, 24.1±1.19 kg/d for 0, 25, 50, and 100g of betaine/d, respectively). No effect of dietary betaine was detected on dry matter intake, feed efficiency, body weight, or body condition score. Percentages of milk fat, lactose, solids-not-fat, and somatic cell count were not altered; however, protein concentration was decreased by betaine supplementation as compared with the control (3.35, 3.28, 3.27, and 3.28±0.07% for 0, 25, 50, and 100 g of betaine/d, respectively). Daily yields of milk protein, fat, lactose, energy-corrected milk, and 3.5% fat-corrected milk did not differ with betaine supplementation. Overall, inclusion of dietary betaine at 100 g/d increased milk yield, whereas all levels of betaine supplementation decreased milk protein percent and slightly altered milk fatty acid profile. Further studies are needed to determine the ruminal fermentation characteristics and the optimum rate of supplemental betaine for dairy cows.

Assessment of management and basic beef quality assurance practices on Idaho dairies.

In 2004 a mail-in survey was conducted to establish a baseline level of awareness and knowledge related to dairy beef quality assurance (BQA) issues in Idaho. A 30-question survey was mailed to every (n = 736) registered Idaho dairy. Two-hundred seventy-three (37%) dairies participated and were categorized as small (n <201 cows; 53.5%), medium-sized (n = 201 to 1,000 cows; 27.1%) or large (n >1,000 cows; 19.4%). The majority of respondents were dairy owners (83%). Eighty-nine percent of respondents indicated they followed BQA recommendations for animal care. The neck region in cows was used by 68% of respondents for i.m. injections and by 80% for s.c. injections. In calves, the values were 61 and 78%, respectively. Seventy-four percent of respondents indicated they had been trained for injections. Training methods cited included veterinarians (19.8%), dairy owners (16.8%), experience (9.9%), and BQA events or schools (4.5%). The importance of BQA in the dairy industry was rated 2.6 on a 5-point scale (0 = low; 4 = high). Participants rated the effect of dairy animals on the beef industry at 2.5. Plastic ear tags were the preferred method of animal identification, with 100% of large dairies, 97.3% of medium-sized dairies, and 84% of small dairies citing their use. Less than 10% used electronic identification for their animals. Almost half (48%) of large and medium-sized (49%) dairies and 32% of small dairies supported a national animal identification program. A mandatory identification program was supported by 41, 69, and 59% for small, medium-sized, and large dairies, respectively. The percentage of dairies keeping records was similar between small (93%), medium-sized (99%), and large (100%) dairies. Most small dairies (58%) used some form of paper records, whereas most medium-sized (85%) and large (100%) dairies used computers for record keeping. The preferred method to market cull cows by Idaho dairies was the auction market (64%), followed by order buyers (17%), direct to the packer (17%), private treaty sales (16%), and forward contracts (1%). To market calves, dairies used private treaty sales (52%), auction markets (42%), order buyers (14%), and forward contracts (1%). The results of this study will be used by University of Idaho Extension faculty in the design, development, and delivery of dairy BQA program information and materials.

Odor Concentrations Downwind of Idaho Dairies and Heifer Facilities

Odor and gas concentrations were sampled on 38 dairies and 15 heifer and calf raising facilities in southern Idaho. Odor detection threshold was measured using a Nasal Ranger field olfactometer, and odor intensity was measured using n-butanol. Gas concentrations for total reduced sulfur (hydrogen sulfide) were measured at each farms most probable odor source, 50 m downwind, and 200 m downwind using a Jerome meter, and ammonia was measured using Drager diffusion tubes. The type and management of manure handling systems were found to have the greatest impact on odor concentration versus the number of animals on the facility. There were observations of individual facilities within each subject group that emitted odors much less and up to twice the group averages. Flushed freestall and scraped freestall systems were shown to have the greatest measured odor concentrations, while open-lot facilities had lower measured levels. Seasonal variations on each type of dairy studied were found to have a significant impact on odor and gas concentrations at the source. Odor concentrations from heifer facilities were found to be similar to those of open-lot dairies. Porous geotextile covers used on secondary manure separation basins were found to be effective in reducing odor concentrations by half. Odors that were in excess of 15 dilutions to threshold, using the Nasal Ranger, were found to be objectionable when odor panelists were located at a rural residence during 50% of the odor measurements. Panelists observing the same level of odor would have found it objectionable nearly 80% of the time if the odor were detected during a party or event at a rural residence.

Emissions from a Dairy Wastewater Storage Pond, Manure Processing Area, and Composting Yard in south-central Idaho

This study evaluated the concentrations and emission rates of ammonia and hydrogen sulfide from a wastewater storage pond, manure processing area, and composting area from a 5,000 cow freestall scrape dairy located in south-central Idaho over a 6-month period. Pollutant concentrations were measured using an Ultraviolet Differential Optical Absorbance Spectrometer and emission rates were calculated using backward Lagrangian modeling via the WindTrax model. Measurements were collected continuously at a final 15-minute integration time. Significant seasonal variability in both concentrations and emission rates of all pollutants were observed between warm (5/31/05 – 9/14/06) and cold (9/15/06 – 12/7/06) periods. Average summertime concentrations adjacent to a 9.8 hectare wastewater storage pond were found to be 556.3 ppb for NH3 and 33.4 ppb for H2S, with emission rates averaging 28.5 µg/m2/s and 4.3 µg/m2/s, respectively. During the cold period, concentrations were found to average 366.3 ppb for NH3 and 310 ppb for H2S, with emission rates averaging 18.4 µg/m2/s and 41.5 µg/m2/s, respectively. These emission rates are similar to those found from dairy lagoons in Ohio, Texas, and Washington. Average concentrations downwind of a 13.3 hectare composting area during the warm period were found to be 472.2 ppb for NH3 and 83.1 ppb for H2S, with average emission rates of 33.4 µg/m2/s and 15.9 µg/m2/s, respectively. During the cold season, average downwind concentrations were 270.7 ppb for NH3 and 461.7 ppb for H2S, and emission rates averaged 17.3 µg/m2/s and 81.6 µg/m2/s, respectively. These emission rates for ammonia were similar to those observed in Texas and Washington.