Changes in Freezing Point of Blood and Milk During Dehydration and Rehydration in Lactating Cows

Effect of Different Watering Regimes in Summer Season on Water Intake, Feed Intake, and Milk Production of Marecha She-camel (Camelus dromedarius)

Simple Summary

Camel livestock is a significant sector of agriculture in Pakistan. Punjab Marecha is the camel breed more diffuse for their production characteristics. In fact, this camel breed is well adapted to the desert ecosystem, tolerating elevated temperatures and dehydration. This study aimed to evaluate the effect of water deprivation on milk production performance in Marecha camels during the summer. Twelve she-camels in the early lactation stage were included. After seven days, camels were divided into three groups: Group 1 (G1) having access to water once a day, Group 2 (G2) having access once every 4 days, and Group 3 (G3) having access once every 6 days. Milk production and daily dry matter were decreased in camels deprived of water for 6 days. The results of the current study suggest that the camel is a productive animal even when subjected to water deprivation; however, its feed intake and milk production are decreased.

Abstract

Twelve lactating healthy Marecha she-camels in the early lactation stage during the summer at Camel Breeding and Research Station Rakh-Mahni (Pakistan) were included. All animals were fed with Medicago sativa and Cicer arientinum ad libitum and divided into three groups in relation to the access to water, after a period of seven days of adaptation to experimental conditions. Group 1 (G1) was considered as control having access to water once every day; Group 2 (G2) had access once every 4 days, while Group 3 (G3) had access once every 6 days. The duration of the study was 60 days with an adaptation period to experimental conditions of 7 days before the onset of the study. Dry matter intake (DMI) was calculated on a dry matter basis. On average the ambient temperature and relative humidity during the trial were 39–41 °C and 55–63%, respectively. The DMI, water intake, milk production, and body weight changes were affected (p < 0.001) during various watering regimes. The mean values of water intake were found to be 82.94 ± 1.34 L higher in G3 than G1 and G2.

Relationship Between Content of Ketone Bodies in Milk and Milk Freezing Point of Polish Holstein-Friesian Cows in Early Lactation

The objective of this study was to determine the relationship between milk β-hydroxybutyrate (BHB), acetone (ACE) as well as parity and lactation stage and milk freezing point (MFP) in Polish Holstein-Friesian cows in early lactation. Additionally, we studied the relationship between milk ketone bodies and daily milk yield (DMY), fat (MF) and protein (MP) content in milk. The data obtained from the Polish Federation of Cattle Breeders and Dairy Farmers, comprised 749,894 test day milk samples, collected between 6 and 60 days in milk (DIM) from 521,049 lactations of 514,066 cows. Milk BHB and ACE were determined using the Fourier transform infrared (FTIR) technology. Four classes of parities were created: first, second, third, and fourth to seventh and two classes of lactation stage: 5–21 and 22–60 DIM. BHB was grouped into five classes: ≤0.05, 0.06–0.10, 0.11–0.20, 0.21–0.50 and >0.50 mmol/L, and ACE was also classified into five classes: ≤0.05, 0.06–0.10, 0.11–0.15, 0.16–0.30 and >0.30 mmol/L. Data on MFP, DMY, and MF and MP content were analyzed using the MIXED procedure of SAS and a linear model in which effects of parity, lactation stage, BHB and ACE classes were included, together with interactions between lactation stage and BHB classes, parity and BHB classes, lactation stage and ACE classes, and parity and ACE classes. The differences among parity, lactation stages, BHB and ACE classes in MFP, DMY, MF and MP were highly significant. There was a clear tendency for decreasing of MFP with increasing of BHB. Such a trend did not occur in case of ACE. DMY and MP decreased and MF increased with increasing BHB or ACE. In conclusion, since MFP can be measured relatively easily and is well related to milk BHB content, it may be used in the prediction of diagnostic models of ketosis based on milk composition.

Heritability and repeatability of milk lactose and its relationships with traditional milk traits, somatic cell score and freezing point in Holstein cows

Lactose percentage (LP) in milk is currently determined in most herd-testing schemes, and globally, it is usually routinely recorded in the framework of the official milk recording procedures. However, few studies have investigated the phenotypic and genetic variability of this component. Data used in the present paper consisted of 59 811 test-day records from 4355 Holstein cows in 266 herds. Heritabilities of LP and lactose yield (LY) were estimated through single-trait repeatability animal models, whereas genetic and phenotypic correlations of LP and LY with milk composition and production traits, somatic cell score and milk freezing point were estimated using bivariate models. Fixed effects included in the analyses were herd-test-date, season of calving, parity, stage of lactation and the interaction between parity and stage of lactation. Random effects were animal additive genetic, within and across lactation permanent environment and the residual. Lactation curves of LP and LY increased from parturition to the peak of lactation and decreased thereafter, mirroring the typical curve of milk yield. Lactose percentage was greater in first- than later-parity cows. Heritabilities of LP and LY were 0.43±0.03 and 0.14±0.02, respectively, and LP and protein percentage were the most repeatable traits. Genetic correlations (r a) of LP with somatic cell score, LY and milk freezing point were -0.22±0.08, 0.28±0.08 and -0.46±0.05, respectively. Genetic relationships of LY with milk yield (r a=0.97±0.00), fat percentage (r a=-0.71±0.06), protein percentage (r a=-0.57±0.06) and protein yield (r a=0.64±0.06) were moderate to strong. Results suggest that milk LP could be considered in breeding strategies to accelerate the gain of correlated low heritable traits. Further research is needed to evaluate the feasibility of including LP in the selection index of Italian Holstein population to address country-specific needs and market demands.

Seasonal variations of Saanen goat milk composition and the impact of climatic conditions

The aim of this research was to investigate the effect of climatic conditions and their impact on seasonal variations of physico-chemical characteristics of Saanen goat milk produced over a period of 4 years. Lactation period (early, mid and late) and year were considered as factors that influence physico-chemical composition of milk. Pearson's coefficient of correlation was calculated between the physico-chemical characteristics of milk (fat, proteins, lactose, non-fat dry matter, density, freezing point, pH, titrable acidity) and climatic condition parameters (air temperature, temperature humidity index-THI, solar radiation duration, relative humidity). Results showed that all physico-chemical characteristics of Saanen goat milk varied significantly throughout the lactation period and years. The decrease of fat, protein, non-fat dry matter and lactose content in goat milk during the mid-lactation period was more pronounced than was previously reported in the literature. The highest values for these characteristics were recorded in the late lactation period. Observed variations were explained by negative correlation between THI and the physico-chemical characteristics of Saanen goat milk. This indicated that Saanen goats were very prone to heat stress, which implied the decrease of physico-chemical characteristics during hot summers.

Influence of stage of lactation and year season on composition of mares' colostrum and milk and method and time of storage on vitamin C content in mares' milk

BACKGROUND

Mares' milk is becoming increasingly popular in Western Europe. This study was thus aimed at investigating the impact of stage of lactation and season on chemical composition, somatic cell count and some physicochemical parameters of mares' colostrum and milk, and at developing a method for the determination of vitamin C (ascorbic acid) in mares' milk and to determine its content in fresh and stored milk.

RESULTS

The analysis conducted showed an effect of the stage of lactation on contents of selected chemical components and physicochemical parameters of mares' milk. In successive lactation periods levels of fat, cholesterol, energy value, citric acid and titratable acidity decreased, whereas levels of lactose and vitamin C, as well as the freezing point, increased. Analysis showed that milk produced in autumn (September, October, November) had a higher freezing point and lower concentrations of total solids, protein, fat, cholesterol, citric acid and energy value in comparison to milk produced in summer (June, July, August). Mares' milk was characterised by low somatic cell count throughout lactation. In terms of vitamin C stability the most advantageous method of milk storage was 6-month storage of lyophilised milk.

CONCLUSION

In general, the results confirmed that mares' milk is a raw material with a unique chemical composition different from that produced by other farm animals.

The freezing point of raw and heat treated sheep milk and its variation during lactation

The freezing point of milk is an important indicator of the adulteration of the milk with water, but heat treatment may also affect its value. The aim of this study was determine freezing point of raw and heat treated sheep milk and its variation during lactation. The freezing point was determined in 42 bulk tank raw sheep milk samples and 42 pasteurized milk samples collected during lactation of sheep at one ecofarm in Moravian Walachia (Valašsko in the Czech Republic). The freezing point was determined in accordance with the standard ČSN 57 0538 using a thermistor cryoscope. The average freezing point of raw milk was -0.617 ± 0.052 °C, with a range from -0.560 to -0.875 °C. The freezing point was lower in the first months of lactation and increased at the end of lactation. The freezing point correlated (r = 0.8967) with the content of total non-fat solids. The average freezing point of sheep milk pasteurized at 65 °C for 30 min was -0.614 ± 0.053 °C, with a range from -0.564 to -0.702 °C. The median of freezing point differences between raw and pasteurized milk was 0.004 °C. Our study extends data about physico-chemical properties of sheep milk and registers for the first time specific changes in the freezing point value of sheep milk by heating.

Invited review: associations between variables of routine herd data and dairy cattle welfare indicators

As farm animal welfare is high on the political and societal agendas of many countries, considerable pressure exists to establish audit programs in which farm animal welfare is routinely monitored. On-farm assessment of animal welfare, however, is time-consuming and costly. A promising strategy to monitor animal welfare more efficiently is to first estimate the level of animal welfare on a farm based on routine herd data that are available in national databases. It is not currently known which variables of routine herd data (VRHD) are associated with dairy cattle welfare indicators (WI). Our aim was to identify VRHD that are associated with WI in a literature review. The 27 VRHD used in this review included the main types of data that are currently collected in national herd databases of developed countries, and related to identification and registration, management, milk production, and reproduction of dairy herds. The 34 WI used in this review were based on the Welfare Quality Assessment Protocol for Cattle. The search yielded associations in 146 studies. Twenty-three VRHD were associated with 16 WI. The VRHD that related to milk yield, culling, and reproduction were associated with the largest number of WI. Few associations were found for WI that referred to behavioral aspects of animal welfare, nonspecific disease symptoms, or resources-based indicators. For 18 WI, associations with VRHD were not significant (n=5 WI) or no studies were found that investigated associations with VRHD (n=13 WI). It was concluded that many VRHD have potential to estimate the level of animal welfare on dairy farms. As strengths of associations were not considered in this review, however, the true value of these VRHD should be further explored. Moreover, associations found at the animal level and in an experimental setting might not appear at the farm level and in common practice and should be investigated. Cross-sectional studies using integrated welfare scores at the farm level are needed to more accurately determine the potential of VRHD to estimate levels of animal welfare on dairy farms.

Milk production and feeding behavior in the camel (Camelus dromedarius) during 4 watering regimens

Camels survive and produce milk during recurrent prolonged hot and dry periods. The objective was to evaluate how different watering intervals affected milk production and feeding. Eight lactating camels (Camelus dromedarius) were recruited and subjected to 4 watering regimens in a Latin square design experiment performed at Haramaya University in Ethiopia. Each regimen lasted 16 d with 5 d of daily watering between periods: water was offered at 1,315 h once daily (W1); on d 4, 8, 12, and 16 (W4); on d 8 and 16 (W8); and on d 16 (W16). One camel became sick in the second period and its results were excluded. Camels were kept in a pen with minimal shade and a noon temperature of 30.9±0.1°C. They had free access to hay and were offered 2 kg of concentrates 3 times daily. At noon on d 1, 4, 8, 12, and 16, a blood sample was taken from the jugular vein before watering. All calves were kept together in a separate pen. Morning and afternoon calves stimulated milk let-down before the camels were hand-milked, after which the calves suckled, emptying the udder. Camels maintained the milk volume during water deprivation for about 1 wk, but they produced less milk during the second week during W16. Morning milk osmolality increased from 315±3 on d 1 to 333±3 mosm/kg on d 4 during W4 and from 321±3 on d 1 to 342±3 mosm/kg on d 8 during W8. After watering at 1315 h, milk osmolality decreased to 316±3 and 323±3 mosm/kg, respectively, the same afternoon and then increased during recurrent water deprivation to 338±3 (W4) and 347±3 mosm/kg (W8) on d 16, respectively. During W16, osmolality increased from 318±3 to 336±3 mosm/kg during the first 4 d of water deprivation, but during the remaining 12 d the further rise in osmolality was not higher compared with that on d 4. The change in milk osmolality was linearly correlated to plasma osmolality (r=0.8), but milk lactose content did not increase. Contrary to widespread belief, camels did not dilute their milk when dehydrated. Instead milk osmolality increased in parallel to blood osmolality. This study provides further support to earlier observations on camels' adaptation to their environment.