Reactive dairy cows are more susceptible to stress, and this may result in negative effects on milk yield and quality. The aims of this study were to investigate the relationships between temperament ...traits and concentration of milk cortisol and oxytocin, milk yield, milkability, and milk quality in Holstein-Gyr cows. Temperament traits were assessed in 76 Holstein-Gyr cows in the milking parlor (by scoring milking reactivity and recording the numbers of steps and kicks during pre-milking udder preparation and when fitting the milking cluster) and during handling in the corral (by measuring the time to enter in the squeeze chute, ET and flight speed, FS). Milk samples were collected for milk quality (% fat, % protein, % lactose, and somatic cell count, SCC), and milk cortisol and oxytocin. Milk yield, milking time, and average flow were also measured. The calmer cows during milking management (class 'low') produced milk with higher protein (p = 0.028) content and tendencies for lower fat (p = 0.056) and higher lactose (p = 0.055) contents. Regarding the hormones, the most reactive cows (class 'high') in the milking and handling corral produced milk with higher concentrations of cortisol (p<0.001) and oxytocin (p = 0.023). In addition, the temperament of the animals affected some of the productive measures evaluated. Cows with reactive temperament had lower milk flow and longer milking time than the intermediate ones and had higher fat and a tendency for lower protein percentage in milk compared to cows with intermediate temperaments. Calm and intermediate cows in the handling corral produced more milk and presented better milkability parameters, such as a shorter milking time and greater average milk flow. Our results suggest that the cows' behavioral reactivity can be related to the intensity of their response to stress during handling.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Aiming to evaluate the effects of increased body energy reserve (BER) in Nellore cows' reproductive efficiency, cows were fed with different nutritional plans to obtain animals with high BER (HBER; ...Ad libitum diet) and moderate BER (MBER: cows fed 70% of HBER group ingestion). To evaluate the BER, cows were weekly weighted and evaluated for subcutaneous fat thickness and insulin serum concentration along the experimental period. At the end of the experimental period, animals were submitted to estrous synchronization and artificial insemination. Animals were slaughtered approximately 120 h after ovulation induction and the reproductive tracts were collected for embryo recovery and samples collection. Cumulus-oocyte-complexes (COC) and follicular fluid were collected from 3-6 mm in diameter ovarian follicles to perform miRNA analysis of cumulus cells (CC) and extracellular vesicles from follicular fluid (EV FF). As expected, differences were observed among MBER and HBER groups for body weight, fat thickness, and insulin serum concentration. HBER animals showed lower ovulation and embryo recovery rates compared to MBER animals. Different miRNAs were found among CC and EV FF within groups, suggesting that the BER may influence follicular communication. This suggests that small follicles (3-6 mm diameter) are already under BER effects, which may be greater on later stages of follicular development.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Anchorages of prestressing wires in timber may be achieved with gluing.•Glued anchorages are not suitable for outer (sun exposed) uses.•Anchorage with nuts are suitable and allow for controlled ...(re)-tightening.•All the systems show a potential for use with long or short (mass-production) elements.
The possibility of improving the bending strength of timber beams through prestress is discussed. Different prestressing and anchoring procedures are investigated: (i) post-tension, with mechanical anchorage on the ends of the wood elements; (ii) pre-tension, with the anchorages being either mechanical, as in the previous system, or glued, with the force being gradually transferred through shear stresses along a certain length of the wire/wood interface. The main conclusion is that any of the procedures may be advantageously used with either small (mass-production) or long glued-laminated timber beams, as a possible alternative to CFRP reinforced beams.
This paper describes the rehabilitation procedure of the roof timber structure of a multiuse pavilion in Viseu, Portugal. The roof structure consists of a series of parallel double timber trusses, ...partially concealed above a polyhedral wooden plank-made ceiling. Recently, the support of one of the trusses failed and another one has been assessed as in a pre-failure condition. Some load-redistribution and the prompt shore of the structure prevented the generalized collapse. The subsequent inspection and assessment led to the conclusion that the primary cause of the collapse was the failure perpendicular to the grain of the solid timber elements inserted between the double rafters and tie-beams. The replacement of the existing with a steel structure, and the repair and reinforcement of the existing wooden trusses, were considered as intervention possibilities. The latter revealed much cheaper, less time-consuming and in line with the international recommendations on rehabilitation works, and was therefore adopted. An innovative solution, consisting of the replacement of the central timber elements in all the supports, resulted in minimum visual impact and improved the load bearing capability beyond its original value. Doi: 10.28991/cej-2020-03091628 Full Text: PDF
The long exposure to heat negatively changes performance and productivity of animals, particularly when heat stress is associated with gestation. Indeed, little is known about the negative effects of ...long-term heat stress on the final gestation of dairy goats. In this context, the physiological and cellular responses of Saanen goats submitted to heat stress (37°C from 10:00 to 16:00 h) were investigated from day 60th pre-partum to day 60th post-partum. At final gestation, 46 pregnant Saanen goats were randomly assigned to the treatments: control (CT; thermal neutral conditions) and heat stress (HS; climatic chamber). After partum, all experimental goats were maintained in thermal neutral conditions. The rectal, dorsal, mammary temperatures and respiratory frequency, cortisol release, milk yield, milk quality, and the genes HSP60, HSP70, HSP90, Glucocorticoid receptor and ACTHR. Goats subjected to HS showed significantly (
P
< 0.05) higher rectal, dorsal, and mammary temperatures and significantly mobilized the increase of respiratory frequency to lose heat as compared to CT goats. The HS challenge significantly increased cortisol release from day 15th pre-partum to day 15th post-partum. CT goats produced more milk than HS from weeks 4 to 10 of lactation (
P
<0.001), with no difference in milk quality. However, on day 15th post-partum, there was a significant effect of HS treatment on the expression of
HSP70
and
ACTHR
genes as compared to CT treatment, confirming the long-term effect of HS on Saanen goats. In conclusion, the physiological parameters studied increased pre-partum in the hottest hour, and cortisol peaked on day 15 pre-partum for heat-stressed goats. Although on the 15th day post-partum, all goats were in thermal comfort, and the physiological parameters were within the normal range, the concentration of cortisol continued to be significantly higher for goats submitted to thermal stress. Indeed, milk yield was greater for goats subjected to pre-partum thermal comfort. Furthermore, the expression of HSP70 and ACTHR genes on peripheral blood mononuclear cells are interesting biomarkers for studying the long-term effect of heat stress on Saanen goats.
The purpose of this research was to investigate the causes and consequences of pHu variations in beef cattle. A group of 176 Nellore beef cattle was evaluated and classified into two different pHu ...groups: High (≥6.0, N = 17) and Normal (<5.8, N = 159). Plasma concentrations of cortisol and adrenocorticotropic hormone, lactate and glycogen muscular content, meat color, shear force and Longissimus thoracis muscle proteomic profile were evaluated and compared between pHu groups. Muscle glycogen content, meat color and shear force statistically differed between pHu groups. Label-free quantitative proteomic analysis revealed ten differentially abundant proteins between pHu groups, involved in metabolic processes and muscle contraction, which also were significantly correlated with pHu. Thirty-six and 31 proteins were exclusively present in Normal and High pHu group, respectively, which were related to TCA cycle, cortisol production, calcium regulation, and antioxidant function. The MYH7, UGP2, H2AFJ and VDAC3 were identified as potential indicators of pHu variations. CALM and NNT appeared to be interesting proteins to understand the metabolic pathways behind pHu. Data are available via ProteomeXchange with identifier PXD009320.
•Pre-partum training are effectives in improving zebuine cows' behavior in terms of milking at the beginning of lactation.•Pre-partum habituation in milking parlor improves milk ejection by ...reflecting on cortisol and oxytocin release.•Pre-partum habituation in milking parlor is effective to reduce stress from the onset of first lactation.
Positive interactions with humans can improve cow behavior and facilitate farm management, especially in dairy production systems in which milking occurs daily. Therefore, this study aimed to investigate the impact of positive tactile stimulation on behavior, and its effect on the milking routine, milk ejection, and milk yield of Gyr cows. Experiment 1 was performed with 40 cows: 20 cows (5 primiparous and 15 multiparous) received positive tactile stimulation (by hands and brushes) in the aisle of the corral during the prepartum period for 14 days; the other 20 cows (5 primiparous and 15 multiparous) did not receive any kind of tactile stimulation (control). Experiment 2 was performed with 40 heifers: 20 heifers were trained to enter the milking parlor and were progressively submitted to positive tactile stimulation (by hands and brushes) and to the milking routine during the prepartum period in the milking parlor for 14 days; the other 20 heifers did not receive any kind of training or tactile stimulation (control). Behavioral data were observed during the beginning of lactation: when the animal entered the milking parlor (stalled, needed help, and attempted to escape), during milking preparation (reaction to udder massage and to the strip cup test), and during milking (reaction to teat cups and whether the animal pulled off the teat cups). Milk yield and residual milk volume were measured and milk samples were collected for analysis of milk composition, somatic cell count, and cortisol and oxytocin in milk. All the experimental cows were suckled on one teat by their calf. Entry into the milking parlor and preparation of the animal for milking are the most critical moments for detecting reactivity to milking procedures. At the same time, the two positive stimulations studied (i.e., handling in the corral or training in the milking parlor) were efficient in improving the behavior of Gyr cows at the beginning of lactation, thus demonstrating that prepartum positive stimulation was effective at reducing the negative behavior of cows during the firsts milkings. Indeed, the percentual of residual milk in primiparous cows subjected to positive milking training was significantly lower than those measured in untrained primiparous and multiparous cows. This result is very promising because it indicates that Gyr heifers, when positively stimulated and trained in the milking routine during the prepartum period, will maintain adequate behavior and excellent milk ejection during their firsts milkings.
•Timber frame joints made up with high-strength concrete and glued-in steel rebars.•Ductile failure, control of span-to-joint moment ratio, possible prefabrication.•Test setups with quasi-pure ...bending and bending/shear/axial interaction.•Geometrically nonlinear modeling with secant rotational stiffness of the joint.•Bending strength seems not to be affected by shear.
This paper is on the numerical and experimental study of a reinforced concrete prosthesis for the corner connections of timber frames. The reinforcement bars are common construction steel ribbed bars glued-in with epoxy resin in the end grain of the timber elements. Two sets of test specimens were tested. One set was stressed through a lattice girder, aiming at imposing a quasi-pure bending state. The other set was tested by directly loading the beam with the actuator. The experimental study was complemented with computational framed models. The joint strength of the connection is similar to that of the connected cross sections. No significant interaction between bending and shear/axial stresses was found.
The aim of this study was to evaluate behavioural and physiological variables of 18 Gir x Holstein calves housed in groups submitted to two treatments: presence (EE) or absence (NE) of environmental ...enrichment. Behavioural variables (walking, feeding, leisure and play behaviour) were analyzed continuously in the first and second hours after brushing using generalized mixed models. Physiological parameters (cortisol, lactate and oxytocin) measured before and after brushing were analyzed using linear models with repeated measures over time. Models included treatment and day fixed effects and treatment x day interaction. The brushing duration was shorter (P = 0.01) for the EE treatment (1.93 ± 0.08 min) compared to the NE treatment (2.47 ± 0.08 min). The animals in the NE treatment allowed longer tactile stimulation time than the EE animals throughout the management days. There was no treatment effect on serum lactate levels before toothbrushing (P > 0.05). After brushing, lactate concentration was lower for the EE treatment (P < 0.01). There was no treatment effect on cortisol before or after brushing. Mean oxytocin levels were higher for EE treatment before and after toothbrushing (P < 0.01). Brushing positively influences the well-being of group-housed calves raised in an enriched environment. Environmental enrichment is a low-cost tool with important positive effects.
This study addresses the hypothesis that different acute stressors can cumulatively decrease milk yield. In fact, in a time of global warming, the impact of environmental stress and farm management ...practices on milk production remains unclear. In this context, our objective was to investigate the effect of acute and cumulative stress on gene expression in mammary tissue and their interactions with physiological responses and milk yield in Saanen goats. Thirty lactating goats were subjected to two treatments: (1) control (CT), in which goats were maintained following a habitual routine under comfort conditions; (2) stress (ST), in which the goats were subjected to different types of environmental stress: heat stress, adrenocorticotropic hormone administration, hoof care management, and exposure to rain. These stressors were performed sequentially, with one stress per day on four consecutive lactation days, to evaluate their effect on milk quality and milk yield. Our results showed that compared to CT goats, cumulative stress increased the gene expression of glucocorticoid receptor (GR), interferon-gamma (IFN-γ), superoxide dismutase (SOD), and catalase (CAT) in mammary tissue, which are indicators of cortisol action, inflammatory response, and antioxidant enzymes. Furthermore, the acute challenges imposed on ST goats changed their rectal temperature and respiratory frequency and increased cortisol, glucose, cholesterol, triglycerides, and high-density lipoprotein release in plasma when compared to CT goats. Although these physiological and metabolic responses restore homeostasis, ST goats showed lower milk yield and higher somatic cell count in milk than CT goats. In conclusion, the results confirmed our initial hypothesis that different acute stressors cumulatively decrease the milk yield in Saanen goats.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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