Relationship between water intake, dry matter intake and daily milk yield on a German research farm

Effects of heat stress on feed intake, milk yield, milk composition, and feed efficiency in dairy cows: A meta-analysis

Heat stress compromises dairy production by decreasing feed intake and milk yield, and it may also alter milk composition and feed efficiency. However, little information is available for evaluating such effects across different levels of heat stress and cows enrolled in heat stress studies. The objectives of this study were to evaluate the effects of heat stress on dry matter intake (DMI), energy-corrected milk (ECM), milk composition, and feed efficiency (kg ECM/kg DMI) and to investigate the relationship between such effects and heat stress intervention and animal characteristics by using meta-analytical approaches. Data from 31 studies (34 trials) fulfilled the inclusion criteria and were used for analysis. Results showed that heat stress decreased DMI, ECM, and milk protein concentration, but did not alter milk fat concentration or feed efficiency. Meta-regression confirmed that such reductions in DMI and ECM were significantly associated with increasing temperature-humidity index (THI). Over the period of heat stress, for each unit increase in THI, DMI and ECM decreased by 4.13% and 3.25%, respectively, in mid-lactation cows. Regression models further revealed the existence of a strong interaction between THI and lactation stage, which partially explained the large heterogeneity in effect sizes of DMI and ECM. The results indicated a need for more research on the relationship between the effect of heat stress and animal characteristics. This study calls for the implementation of mitigation strategies in heat-stressed herds due to the substantial decrease in productivity.

Effects of rosemary (Rosmarinus officinalis) by-products and linseed (Linumusitatissimum) intake on digestibility, body weight gain, and estimated tissular composition in cull fat-tailed ewes

The aim of this study was to evaluate the effect of rosemary (Rosmarinus officinalis) residues (RR) as dietary supplement in association with linseed (Linumusitatissimum) on digestive aspects and body weight (BW) gain in fat-tailed Barbarine ewes. To achieve this, 24 cull ewes (BW: 33 ± 2.7 kg) were divided into four groups receiving a basal diet composed of 500 g of straw for two groups (S) and 300 g of straw in addition to 200 g of RR for two other groups (R). All animals received 750 g of concentrate; the usual concentrate (UC) was offered for one S (S-UC) and one R group (R-UC); the linseed concentrate (LC) was also offered for one S (S-LC) and one R group (R-LC). The fattening and digestibility trials lasted 90 days. The dry matter (DM) intake and digestibility were similar across the groups. However, the crude protein (CP) intake and digestibility and the neutral detergent fiber intake were significantly affected by the treatments (P > 0.05). The nitrogen intake (NI), the fecal, and retained nitrogen were significantly affected by the regimen (P < 0.05); however, the urinary nitrogen was unchanged. The nitrogen balance was positive for all groups averaging 60% of the NI. The ruminal pH, ammonia nitrogen, and protozoa concentration were not affected by the RR intake and linseed supply; however, the control time affected significantly these parameters. Final BW, the average daily gain, the muscle, and fat contents were neither affected by the basal diet nor by the concentrate type (P > 0.05). In conclusion, the RR intake in association with linseed did not alter the animal's performances by improving their productive characteristics and consequently, the commercial value of this sheep's category.

The relationship between methane emission and daytime-dependent fecal archaeol concentration in lactating dairy cows fed two different diets

Archaeol is a cell membrane lipid of methanogenic archaea excreted in feces and is therefore a potential biomarker for individual methane emission (MEM). The aims of this study were to examine the potential of the fecal archaeol concentration (fArch) to be a proxy for MEM prediction in cows fed different diets and determine if the time of fecal collection affected the archaeol concentration. Thus, we investigated (i) the variation of the fArch concentration in spot samples of feces taken thrice within 8 h during respiration chamber measurements and (ii) the effect of two diets differing in nutrient composition and net energy content on the relationship between fArch and MEM in lactating cows. Two consecutive respiration trials with four primiparous and six multiparous lactating Holstein cows were performed. In the first trial (T1) at 100±3 d in milk (IM), a diet moderate in starch and fat content was fed for ad libitum intake, whereas in the second trial (T2) at 135±3 d IM, cows received a diet lower in starch and fat. Individual MEM (g d-1) was measured for 24 h. Fecal samples were taken at 06:30, 10:00, and 14:30 LT and analyzed for fArch using Soxhlet lipid extraction and GC–MS. Cows produced less methane (364 g CH4 d-1) during T1 and had significantly lower fArch concentrations (37.1 µg g-1 dry matter; DM) compared to T2 (392 g CH4 d-1 and 47.6 µg g-1 DM). A significant positive relationship between fArch (µg g-1 fecal DM) and MEM, expressed on a dry matter intake (DMI) basis (g kg-1 DMI), was found (R2=0.53, n=20). Among samples collected over the day, those collected at 10:00 LT provided the best coefficient of determination for MEM (R2=0.23). In conclusion, fArch offers some potential in serving as a proxy for innovative breeding schemes to lower enteric methane when fecal samples are taken at a certain time of the day, but more data on the sources of variation of the MEM : fArch ratios are required.

The effect of water restriction on physiological and blood parameters in lactating dairy cows reared under Mediterranean climate

OBJECTIVE

This study was conducted to evaluate the effect of water restriction (WR) on physiological and blood parameters in lactating dairy cows reared under Mediterranean climate.

METHODS

The trial lasted 16 days preceded by two weeks of adaptation to the experimental condition in spring 2014 on 6 dairy cows in mid-lactation. These cows were allowed water ad libitum for 4 days (W100) (hydration period), then split into 2 groups, one group has received 25% and the other 50% of water compared to their mean water consumption during the hydration period; then rehydrated for 4 days. Feed intake and physiological parameters: respiratory rate (RR), heart rate (HR), and rectal temperature (RT) were recorded twice a day. Blood was collected once a day and analyzed for serum concentration of glucose (Glc), triglycerides (TG), cholesterol (Chol), urea (Ur), creatinine (Crea), and total protein (TP) by enzymatic colorimetric method and cortisol (Cort) by radioimmunoassay.

RESULTS

Total dry matter intake (TDMI) was affected by WR. A decrease in TDMI was observed in WR groups compared to W100 group (effect, group, period, day, group×day, period× day: p<0.001). Also, WR resulted in a significant increase in RR, HR, RT in WR groups than in W100 group (effect, group: p<0.001). In addition, an increase in the serum concentration of Glc, TG, Chol, Ur, Crea, TP, and Cort was noted in WR groups (effect, group, period, day: p<0.001).

CONCLUSION

This study has shown the ability of cows raised in a Mediterranean climate to cope with different levels of WR and thus reach a new equilibrium. As result, elucidates the important role of water as a limiting factor for livestock in environments with low water availability.

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.