The effect of polyethylene hutches wrapped in aluminized reflective covers (ARC) on health and performance of pre-weaned Holstein heifers during summer was evaluated. Ambient and hutch temperature and temperature-humidity index (THI) were also assessed. The study was conducted from June to October 2016 where temperature, humidity, and THI ranged from -1.3 to 38.4°C, 9.8 to 99.7%, and 33.6 to 81.1 units, respectively. Heifers enrolled at 1 d of life and housed in individual polyethylene hutches with (covered) or without (control) ARC were monitored until 60 d of life in 2 study groups (SG1, n = 94, monitored from June to September; and SG2, n = 101, monitored from August to October 2016). Calves were assessed twice per week for health status, behavior, rectal temperature, and respiratory rate. Similarly, hutch inner wall and sand bedding temperatures were determined for comparison between covered and control hutches housing calves. Four empty hutches per treatment group were continuously monitored for temperature and THI. The odds (95% confidence interval) of presenting diarrhea were 1.30 (1.01-1.60) times greater for calves housed in covered hutches than for those in the control group. Similarly, the odds of an abnormal ear score were 1.40 (1.03-2.00) times greater for calves in covered hutches compared with calves in control hutches. The odds of nasal discharge, eye discharge, and clinical dehydration did not differ between treatment groups. Rectal temperatures and respiratory rates were also similar in both groups. No differences were found in average daily gain between calves housed in covered and control hutches. Calf location determined at a fixed time during the day (starting at 1200 h) was associated with the use of ARC. The odds of remaining inside the hutch were 1.33 (1.03-1.70) times greater for calves housed in control compared with covered hutches. Overall, the average of hutch interior temperature was higher in covered compared with control hutches in both studies (SG1, 23.2 ± 0.06 vs. 22.8 ± 0.06°C; SG2, 17.1 ± 0.07 vs. 16.9 ± 0.07°C). Hutch THI was higher in covered empty hutches compared with control hutches in both study groups (SG1: 68.6 ± 0.06 vs. 67.6 ± 0.06°C; SG2: 60.2 ± 0.08 vs. 59.6 ± 0.08°C). Average temperature (measured at 1200 h) of the inner surface of the hutch wall was lower in covered compared with control hutches by 1°C (24.4 ± 0.13 vs. 25.4 ± 0.13°C), whereas the temperature of the sand bedding did not differ between groups. Our results suggest that the use of ARC did not generate a hutch microclimate that resulted in significant improvements on health and performance of pre-weaned dairy calves under these specific study settings.

Simple SummaryImproving efficiency in beef cattle production requires the adoption of technologies that are low cost but high in return. High potency growth-promoting implants (HGPs) are widely used under feedlot conditions but there are few reports of their use under grazing conditions. We conducted a trial to assess whether the use of high potency HGPs have advantages for grass-finished cattle. Our results were similar to those reported for feedlot cattle, showing that the quality of the pastures was good enough to take advantage of the HGP technology, generating a marginal income that justifies the use of technology under grazing conditions.AbstractHigh potency growth promoter implants (HGPs) are widely used under feedlot conditions but there are few reports under grazing conditions. The study’s goal was to assess the effect of HGPs on the average daily gain of steers fattened in pastures. A total of 57 crossbreed steers (Hereford × Angus)—initial body weight = 356.65 kg ± 5.04 (SEM)—were randomly allocated to one of three groups: Control without HGP (n = 19), Synovex group (n = 17), and Revalor group (n = 21). The fattening period was 67 days using paddocks of Lolium perenne L. and Trifolium repens L. Body weight was recorded three times in the period. The data were analyzed using an analysis of covariance with a level of significance of 5%. The average daily gain (ADG) (1.55 ± 0.07 and 1.48 ± 0.09 kg/d) and the total weight gain (103.4 ± 4.9 and 99.2 ± 5.8 kg) were similar for Revalor and Synovex, respectively (p > 0.05). Moreover, HGP groups showed higher ADG and total weight gain (p < 0.01) than the control group (ADG = 0.93 ± 0.08 kg/d and a total weight gain of 62.2 ± 5.2 kg). Final body weights were 527.8 ± 8.5 kg and 512.2 ± 9.9 kg for Revalor and Synovex, respectively; and 479.9 ± 10.1 kg for Control. In conclusion, grazing-finished steers showed better performance when high potency HGPs were used, improving the ADG and final live body weight, generating a marginal income that justifies the use of the technology under grazing conditions

The objective of this study was to evaluate the efficacy of two non-antibiotic treatment options for digital dermatitis (DD) in an organic certified dairy farm. A randomized clinical trial was conducted using 70 multiparous Holstein cows with an early DD lesion at a USDA certified organic dairy farm in Northern Colorado, USA. Cows were enrolled in the study based on the presence of early DD lesions (scores M1 and M2) and randomly assigned to one of three treatments: (1) topical application of copper sulfate and iodine (CUI); (2) topical application of honey and iodine (HOI); and (3) control subject to no treatment (CON). Cows were evaluated at enrolment and on days 3, 12, 28, and 120 post treatment for pain and lesion size and received a locomotion and a lesion score. Cure was defined as the transition from active to non-active stages (M1/M2 to M0 or M4).The formulations had variable effects on the treatment of DD. The cure rate was numerically higher for CUI on all follow up days. The proportion of cows experiencing pain on d3 after treatment was greater in CON, followed by HOI and CUI. However, this proportion increased in HOI during the follow up period. The CUI group had a greater reduction in lesion size and larger lesions persisted in HOI. Non-antibiotic treatment formulations were partially effective in the treatment of DD in organic dairy cows: The two nonantibiotic formulations resulted in an earlier transition to mature lesions compared with the control group. The CUI combination was the most effective treatment in reducing lesion size, pain, and lameness in affected cows. However, this combination had short-term efficacy, which did not persist throughout the duration of the study. The HOI combination produced only transient reduction in lesion size.

ABSTRACT. Heat stress has been recognised as a serious problem in dairy farms. The study goal was to assess the effects of climatic conditions on physiological and behavioural responses of dairy cows in Central Chile. Data of tympanic temperature (TT), panting score, respiration rate (RR), and shade utilization of cows from two genotypes, Holstein (H) and Holstein x Montbeliarde (HM), were collected twice per day (AM/PM) during three periods of the summer season in Central Chile. Moreover, three thermal comfort indices: Comprehensive climate index (CCI), temperature humidity-index (THI), and adjusted THI were estimated using meteorological data. The hour of each day was classified as "Normal" or "Stressful" based on CCI threshold of 25 °C. Statistical analysis included ANOVA, repeated measures analysis and Chi square test (α=0.05). There was an interaction of genotype x CCI condition x period (P=0.0026) with the highest TT of both genotypes under a stressful condition within each period. In addition, interactions of genotype x hour (P<0.0001) and genotype x CCI condition (P<0.0002) were also observed. The HM cows showed greater TT than H cows in both CCI conditions. The RR was higher during the afternoon and a greater proportion of cows used shade at "Mild" and "Moderate" CCI categories (P<0.001). Both genotypes showed some degree of heat stress, but cool nights and shade seem to be enough to allow to cows' cope with the challenging diurnal conditions observed in the summer season. A study of these effects on milk production is necessary to confirm or discard the previous.

A. Velásquez, and G. Pichard. 2010. In vitro protein breakdown by enzyme extracts of rumen origin: comparison with methods in situ and proteases of Streptomyces griseus. Cien. Inv. Agr. 37(3): 57-70. Proteolytic activity of enzymatic extracts generated from rumen microorganisms cultivated in vitro was evaluated. The incubation of rumen fluid used different substrates to generate a higher enzyme concentration and promote a broad spectrum of hydrolytic activity. The composition of the substrates used in the cultivation of the fluid was enriched in protein, starch or cell wall. Enzyme preparations were evaluated by incubating in 30 mL of buffer 50 mM Tris-HCl (pH 6.5) at 39 ºC during 48 hours, 100 mg of crude protein from feeds soybean meal, canola meal, sunflower meal, gluten feed, dehydrated alfalfa meal, berseem clover, oat forage and perennial ryegrass. Enzyme extracts from cultivated rumen fluid showed an average protein breakdown of 75.5%, in eight feed samples tested. This value was very close to that measured with the technique of proteases from Streptomyces griseus (74.6% CP), but significantly lower (P≤0.05) than the one obtained by the in situ methodology (84.8% CP). The technique with extracted rumen enzymes showed higher level of proteolysis in the early hours of incubation (6 H) compared to the other techniques. These results suggest that the enzyme preparations of ruminal origin have the ability to predict degradability of feed proteins in the rumen, particularly in the first phase when most of proteins are hydrolyzed and become available for microbial utilization.

C. Barchiesi, P. Williams, and A. Velásquez. 2018. Extrusion of lupin and pea decrease the ruminal degradability improving true ileal digestibility of crude protein. Cienc. Inv. Agr. 45(3): 231-239. The aim of this work was to evaluate the effect of the extrusion of dehulled lupins (Lupinus albus L.) and peas (Pisum sativum L.) on the ruminal degradability and intestinal digestibility of their protein contents. Ruminal degradability was evaluated in situ in the rumens of two fistulated cows. The true ileal crude protein (CP) digestibility was evaluated via a bioassay with Sprague Dawley laboratory rats as the animal model. Extrusion caused soluble fraction decreases in both feeds (P<0.05), with a 29 % decrease in the extruded dehulled lupins (EDL) and a 59 % decrease in the extruded peas (EP). The degradable fraction (B) in EP increased by 19 % compared to that in raw peas (RP) (P<0.05), and there was no effect of extrusion on the degradable fraction in lupins (P>0.05). Extrusion decreased the effective degradability (ED) of lupins by 12 % (P<0.05). Moreover, in EP, extrusion presented no effect on the ED (P>0.05). The extrusion process had a greater impact on the reduction of the effective degradability in lupins than it did in peas. Nevertheless, extrusion increased the true ileal CP digestibility of the ruminal postfermentation residues in both feeds.

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Extracts of Saccharomyces cerevisiae (Sc) yeast were generated using a biotechnological solid-state fermentation method. The organic material used for fermentation consisted of a variety of fibrous substrates of agricultural origin, and their effect on the chemical composition and productivity of cellular biomass generated was evaluated. The substrates studied included the following: wheat straw, WS; barley straw, BS; chili stubble, CS; oat hull, OH and starch powder, SP (control). For incubation with Sc, 2 g of (dry) vegetable substrate were added to 12 mL of cultivation medium. The fermentation time was seven days under aerobic conditions (pH 5, 26ºC). After extraction of the yeast biomass, its chemical composition and productivity were analyzed. The results showed an effect (P≤0.01) of the type of vegetable substrate fermented on the crude protein (CP) and true protein (TP) contents of the yeast biomass. The highest concentration of CP was obtained by fermentation of the control TSP (treatment with the starch powder substrate ) (506.3 g kg -1 DM), followed by the treatment TOH (474.5 g kg -1 DM). The productivity of the yeast biomass was affected by the type of substrate fermented (P≤0.001). The highest value was obtained with TSP (327.10 mg g -1 ), followed by TOH (treatment with the oat hull substrate) (207.08 mg g -1 ). The lowest efficiency was measured in TCS (156.30 mg g -1 ). On the basis of these results, it may be inferred that an extract of high CP can be obtained from yeast (Sc) by the fermentation of fibrous substrates.