Changes in the Qualitative Composition of the milk of Holstein Cows During Summer Chronic Heat Stress

Seasonal summer heat stress leads to significant economic losses, resulting in a drop in milk yield in dairy cows and a deterioration in milk quality. The purpose of this study was to determine the changes in some qualitative parameters of milk in Holstein cows during chronic heat stress on one of the largest commercial dairy farms Ukraine (50°49′14″ N, 31°49′23″ E). Five multiparous cows of medium lactation with a milk yield of about 30 kg per day were randomly selected into the reference (in the spring, at the end of May) and the experimental group (in the summer, at the end of August). Milk samples were taken from cows during the morning milking. Qualitative analysis of milk included the identification of milk solids-not-fat, density, mass fraction of lactose, fat, protein and minerals, as well as the freezing point, electrical conductivity and active acidity using ultrasonic method. Animals were kept in naturally ventilated barns. The total mixed single-type balanced diet consisting of corn silage and concentrates that the cows received remained unchanged. The sampling of milk from cows of the experimental group was preceded by a continuous 26-day hot period, during which the maximum daily values of the temperature and humidity index did not fall below 72 units. The results showed that in the milk of the animals of the experimental group there was a significant decrease in the content of milk solids-not-fat, the mass fraction of fat and protein (P0.05). The mass fraction of lactose and minerals tended to increase. It should be noted that the average daily milk yield of dairy cows in the herd in spring and summer was almost at the same level. In conclusion, the results of the study showed that high summer temperatures lead to a deterioration in the quality of milk in Holstein cows. Despite the decrease in milk density and freezing point, these figures met the requirements of the standard. Organoleptic indicators of milk, electrical conductivity and active acidity of milk did not change in hot weather, their value indicated the naturalness of milk. The mass fraction of milk fat, which undergoes the greatest change under the influence of seasonal heat stress, is one of the most valuable components of milk, which has a direct effect on nutritional value and purchase price of raw milk. Therefore, a further deeper study of the fatty acid composition of milk using the method of chromato-mass spectrometry will provide valuable data necessary to search for possible herd management strategies to maintain high milk quality under conditions of seasonal heat stress

FACTORS INFLUENCING PHOSPHORUS EXCRETION BY HORSES

Excessive phosphorus (P) excreted by animals can affect water quality and cause eutrophication. Better understanding of factors that influence P utilization and excretion in horses may reduce the environmental impact of P. Two animal experiments were conducted that examined P excretion by horses. The efficacy of titanium dioxide as an external marker to calculate digestibility was studied concurrently with both animal experiments. Additionally, pasture P concentrations were evaluated over the growing season using near-infrared spectroscopy (NIRS). Experiment 1 examined P excretion by post-lactational mares fed a low P diet immediately prior to weaning compared to non-lactating controls fed an adequate P diet. Post-lactational mares excreted more P compared to controls. Experiment 2 compared P excretion in horses fed to lose, maintain, or gain weight. Horses fed to lose weight tended to excrete more fecal P compared to horses fed to gain weight and had increased markers of bone turnover. The efficacy of titanium dioxide for estimating fecal output from limited fecal grab samples was variable. Titanium dioxide may be useful in situations where many fecal samples are collected over 5 d, but may not be as accurate if one fecal grab sample is expected to be representative of fecal output. Experiment 3 focused on examining the changes in pasture mineral concentration over the season using NIRS. A discussion of how these results may inform equine P supplementation programs is included. Overall, the work in this dissertation suggests that factors that influence P excretion in the horse include the dietary availability of P, physiological status, and active weight change. These variables can be incorporated into feeding programs to meet horses’ needs more closely while minimizing P excretion in the environment

Comparison of early (March) and late (June) calving systems on cow and pre-weaning calf performance and cost of production on western Canadian Prairies

A two-year study (2007, 2008) was conducted to evaluate the effects of two calving systems, early (March; Early Calving System (ECS)) vs. late (June; Late Calving System (LCS)) on cow, pre-weaning calf performance and feeding system management and costs. Both early and late calving systems were managed at three locations on the Canadian Prairies: Agriculture and Agri-food Canada (AAFC)-Brandon Research Centre (Brandon, Manitoba); AAFC-Semi arid Prairie Agricultural Research Centre (Swift Current, SK); and Western Beef Development Centre (Lanigan, SK). Four feeding management systems (drylot (DL), pasture (PG), swath-windrow (SG) and bale grazing (BG)) were utilized at all three locations to maximize grazing systems. Management of animals through the four different feeding systems was found to meet or exceed protein and energy requirements according to NRC (2000). Differences in cow body weight (BW) (P=0.001; location) were observed across locations at pre-calving and weaning periods although there were no obvious patterns when comparing across calving systems. A significant three way interaction was observed for cow BW at breeding (P=0.003), and for cow body condition score (BCS) at breeding (P=0.002). Body condition score at breeding indicated there was a significant (P=0.002) three way interaction, where there were no significant interactions when comparisons across calving system within the same year (Y) and location (L) were performed for Brandon and Lanigan in 2007 and for Lanigan in 2008 also, therefore no improvements in one calving system compared to the other. At Brandon in 2007, ECS cow BCS were similar to LCS cows. In 2007 and 2008, the inverse occurred at SC where LCS cows had greater BCS compared to the ECS. The same two way (Calving System x Location) interaction was significant at pre-calving and weaning for both cow rib (P=0.003; P=0.007) and rump fat (P=0.002; P=0.02) where Lanigan had significantly lower rib and rump fat for the LCS as compared to the ECS. Rib and rump fat measurements did not follow a typical pattern. Fluctuations in body fat reserves varied depending on the calving system and location. Even though differences (P0.05) in reproductive performance between the two calving systems within the management of the current study. Pregnancy rate, calving rate, calving span and weaning rate were similar for both early and late calving systems. In 2007, calf mortality on average was higher for LCS (5%) vs ECS (1.7%) and the inverse occurred in 2008, where LCS had lower calf mortalities than did ECS, 3.3% and 4%, respectively. Most calf mortalities were born dead or weak. There appeared to be no negative impact on calf mortality with early or late calving systems. A significant two way (Calving System x Year) interaction was observed for calf BW at birth (P=0.002) (Table 4.4). Treatment (Calving System) (P<0.0001) main effect was significant for ADG (Table 4.4). The average values for calf birth weights for ECS in 2007 and 2008 were 42.1 and 41.2 ± 0.45 kg and for LCS in 2007 and 2008 were 41.4 and 44.1 ± 0.47 kg, respectively. Birth weights in 2007 between ECS and LCS were not different but in 2008 calf birth weight for LCS was heavier (P<0.05) than ECS calves. As expected calf birth weights were affected by L (P<0.0001). Calf birth weights were 44.8, 40.5 and 41.5 ± 0.8 for BR, SC and LA. Weaning rate was not affected by calving system, location or year. Pre-weaning ADG was 1.13 and 0.96 ±0.01kg d-1 for ECS and LCS, respectively. Weaning weights were therefore significantly (P<0.05) heavier for ECS as compared to the LCS, 273 and 240 ±1.82 kg, respectively. The results of cow and calf performance indicate that calving later in the year does not significantly affect cow performance or reproductive efficiency but calf growth rate is significantly affected largely due to the time of year. Labour and feeding system management and costs are typically lower for LCS because of the ability to manage the cow herd on pastures and extended grazing systems which reduces the need for stored feeds during periods of cold weather

Western Diet-Fed, Aortic-Banded Ossabaw Swine: A Preclinical Model of Cardio-Metabolic Heart Failure.

The development of new treatments for heart failure lack animal models that encompass the increasingly heterogeneous disease profile of this patient population. This report provides evidence supporting the hypothesis that Western Diet-fed, aortic-banded Ossabaw swine display an integrated physiological, morphological, and genetic phenotype evocative of cardio-metabolic heart failure. This new preclinical animal model displays a distinctive constellation of findings that are conceivably useful to extending the understanding of how pre-existing cardio-metabolic syndrome can contribute to developing HF

Keep on track:Monitoring growth and development in children born preterm and full-term

Environmental factors in early life influence early development and growth, and influence long-term health. In this thesis we showed that in premature infants, the length and growth of the cerebral cortex (corpus callosum) is a good marker of brain growth and a predictor of later neurological development. An eye-tracking test (watching a video) at the age of 1 year also appeared to be a predictive factor for overall cognitive and motor development 1 year later. We also found that weight gain after preterm birth is associated with body composition in childhood. We also compared 2 methods of measuring body composition in children (DXA and ADP) and found that the results of fat mass (percentage) and fat-free mass at 3-5 years of age differ significantly between both methods, and that these differences are greater in very preterm children compared to full-term children. We present improvements to the algorithm to improve results with ADP. We also investigated sleep and found that parent-reported sleep characteristics and problems are similar between very preterm and full-term children at the age of 3 years. In the general population, we have shown that low birth weight (&lt;2500 grams) and growth retardation during fetal life and childhood are associated with longer sleep duration and higher sleep efficiency at 10-15 years of age. Furthermore, at the same school age, greater intraday variability (fragmentation of the 24-hour activity rhythm) was associated with a higher fat mass index and higher visceral fat mass in boys

Association of physical exercise and calcium intake with bone mass measured by quantitative ultrasound

<p>Abstract</p> <p>Background</p> <p>Interventions other than medications in the management of osteoporosis are often overlooked. The purpose of this study was to investigate the association of physical activity and calcium intake with bone parameters.</p> <p>Methods</p> <p>We measured the heel T-score and stiffness index (SI) in 1890 pre- and postmenopausal women by quantitative ultrasound (QUS) and assessed physical activity and dietary calcium intake by questionnaire. Participants were divided according to their weekly physical activity (sedentary, moderately active, systematically active) and daily calcium consumption (greater than or less than 800 mg/day).</p> <p>Results</p> <p>SI values were significantly different among premenopausal groups (p = 0.016) and between sedentary and systematically active postmenopausal women (p = 0.039). QUS T-scores in systematically active premenopausal women with daily calcium intake > 800 mg/day were significantly higher than those in all other activity groups (p < 0.05) independent of calcium consumption.</p> <p>Conclusions</p> <p>Systematic physical activity and adequate dietary calcium intake are indicated for women as a means to maximize bone status benefits.</p

Ultrasound Determination of Absolute Backscatter from Arterial Wall Structures

This thesis presents an ultrasound technique for measuring the absolute integrated backscatter (IBS) of arterial wall structures through an intervening inhomogeneous soft tissue layer. The aberrating effect of this tissue layer is minimized by normalizing the measured IBS from the wall region of interest with the IBS from an adjacent range cell in blood. The technique may become a tool to differentiate between stable and vulnerable plaques in the carotid artery