Do different cow types respond differently to a reduction of concentrate supplementation in an Alpine low-input dairy system?

Metabolic and productive adaptive response of beef cows to successive short-nutritional challenges

This study aimed to analyze the response of lactating beef cows to repeated short nutritional challenges with their performance parameters and plasma metabolites. Multiparous lactating beef cows were subjected to three repeated nutritional challenges in the fourth month of lactation. Each challenge consisted of a 4-d feed restriction (55% of their average energy and protein requirements), followed by a 3-d refeeding period (100% requirements). Cows were classified into two groups differing in their performance (milk yield) and metabolic adaptation [non esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB)] to diet changes (metabolic response, MR): High and Low MR cows, where the High MR cows showed a faster and larger response to diet changes than the Low MR cows (P < 0.001). The loss in milk yield during restriction was the smallest in challenge 1 (P < 0.001). Milk urea increased during restriction in challenges 1 and 2 (P < 0.001). The High MR cows had greater NEFA concentrations than their Low MR counterparts during restrictions, and greater BHB concentrations during the restriction of challenge 2 (P < 0.001). Restriction increased NEFA, BHB (only in the High MR cows) and urea (P < 0.01). During refeeding, both milk yield and plasma metabolites recovered basal values (P > 0.05). These results highlight the ability of beef cows to respond to and recover from successive short-term nutrient restrictions, and that despite a certain degree of sensitization of milk yield may have occurred, there were only minimal changes in the metabolic strategies triggered to cope with repeated underfeeding.

Environmental Assessment of Austrian Organic Dairy Farms With Closed Regional Production Cycles in a Less Favorable Production Area

Extensive dairy production in less favorable production areas has a long tradition in Austria. Nevertheless, dairy production also contributes considerable environmental impacts (EIs), e.g., greenhouse gas emissions, nutrient losses, and land use. Therefore, 20 organic dairy farms located in the Lungau region in Austria were assessed concerning their EIs via life cycle assessment (LCA). Cumulative exergy demand (CExD), normalized eutrophication potential (EP), aquatic ecotoxicity potential (AE), and global warming potential (GWP) were considered as impact categories to describe the farms' EIs. The farms were part of a pilot project aiming to produce high-quality dairy products and keep production cycles closed within the project region. Consequently, the purchase of key off-farm resources was only possible within the project region. We adapted existing life cycle inventories to account for those regional resource purchases. Subsequently, the EIs of the 20 farms were related to the functional units (FUs) of 1 kg energy-corrected milk (ECM) and 1 ha agricultural area for milk production and compared to a representative model dairy farm (MDF) that was created based on statistical data and average production values of organic Austrian dairy farms. Compared to the MDF, results show an ~58% lower EP per ha and 44% per kg ECM of the Lungau farms. Further, the CExD per ha was about 24% lower due to a lower use of resources caused by the lower production intensity of the Lungau farms. Regarding GWP, Lungau farms are favorable considering 1 ha as the FU, whereas the MDF seems advantageous if 1 kg ECM is used as the FU. However, caused by a high variation of purchased roughage and the lower production intensity, the Lungau farms cause higher AE, regardless of the FU. Overall, we identified three principal production parameters determining the environmental performance of milk production in a closed production cycle in a less favorable area, namely, (1) the stocking rate, (2) the fed concentrate, and (3) the purchased roughage. Using those inputs at moderate intensity, the extensively managed Lungau farms can competitively contribute to producing food, thus highlighting the importance of site-adapted agriculture.

Characterisation of productive performance, body reserve dynamics and energy metabolic parameters of Holstein Friesian and Normande dairy cows managed in a low-input pastoral dairy system

ContextDairy cows with autumn-calving season in low-input pastoral systems are subjected to challenging conditions as their early lactation falls in autumn and winter when shortages in pasture availability and harsh weather conditions often occur.AimsWe aimed to assess the associations between breed (Holstein Friesian (HF) vs Normande (NR)) and stage of lactation on productive and metabolic responses over lactation in a low-input pastoral dairy system.MethodsTwenty-seven HF (n=14) and NR (n=13) cows were studied. Milk yield was measured fortnightly, and milk composition, milk solid yield, liveweight (LW), body condition score (BCS) and blood plasma energy metabolites were assessed monthly.Key resultsThe greater milk for HF versus NR cows (e.g. 17.4 vs 12.1±1.0kg/day of milk; P&lt;0.001) were associated with a lower LW (510 vs 540±10kg; P=0.021) and BCS (1.84 vs 2.37±0.10; P=0.001) at nadir for HF than NR cows. Blood plasma concentrations of non-esterified fatty acids (NEFA) were high for longer in HF versus NR cows (18 vs 8 WRC). Plasma glucose was greater (P=0.002) and insulin was lower (P=0.021) for HF versus NR cows at 3 WRC. During mid-lactation, glucose (22 WRC, P=0.021) and insulin (26 to 34 WRC, P≤0.041) were lower for HF vs. NR cows.ConclusionsBecause of their lower milk yields, NR cows had a shorter period of body reserves mobilisation, which was associated with an earlier decrease of plasma concentrations of NEFA and greater insulin concentrations at 3 WRC, and then again during mid-lactation when LW and BCS were also greater for NR cows.ImplicationsIn constraining pastoral environments, NR cows would redirect fewer nutrients for milk synthesis, leading to lower depletion of body reserves, which could be associated with a better ability to cope with winter challenging conditions. Although HF cows had a greater depletion of body reserves, there was no increase in the incidence of health problems for these cows.

Plasma concentrations of branched-chain amino acids differ with Holstein genetic strain in pasture-based dairy systems

In pasture-based systems, there are nutritional and climatic challenges exacerbated across lactation; thus, dairy cows require an enhanced adaptive capacity compared with cows in confined systems. We aimed to evaluate the effect of lactation stage (21 vs. 180 days in milk, DIM) and Holstein genetic strain (North American Holstein, NAH, n = 8; New Zealand Holstein, NZH, n = 8) on metabolic adaptations of grazing dairy cows through plasma metabolomic profiling and its association with classical metabolites. Although 67 metabolites were affected (FDR < 0.05) by DIM, no metabolite was observed to differ between genetic strains while only alanine was affected (FDR = 0.02) by the interaction between genetic strain and DIM. However, complementary tools for time-series analysis (ASCA analysis, MEBA ranking) indicated that alanine and the branched-chain amino acids (BCAA) differed between genetic strains in a lactation-stage dependent manner. Indeed, NZH cows had lower (P-Tukey < 0.05) plasma concentrations of leucine, isoleucine and valine than NAH cows at 21 DIM, probably signaling for greater insulin sensitivity. Metabolic pathway analysis also revealed that, independently of genetic strains, AA metabolism might be structurally involved in homeorhetic changes as 40% (19/46) of metabolic pathways differentially expressed (FDR < 0.05) between 21 and 180 DIM belonged to AA metabolism.

Effect of low and high concentrate supplementation on health and welfare indicators in different breeds in small-scale mountain dairy farms

We investigated and compared the effects of low and high concentrate supplementation in terms of animal welfare, health and reproductive performance in two different dairy cow breeds on small-scale mountain farms. 64 South Tyrolean dairy farms were evaluated using an on-farm assessment for animal-based and resource-based welfare indicators, data from test day records, and a questionnaire for the farmer. Farms were divided into four groups: low input Tyrolean Grey (L-TG), low input Brown Swiss (L-BS), high input Tyrolean Grey (H-TG) and high input Brown Swiss (H-BS). Effects of intensity level, breed and their interaction were calculated and analyzed statistically. The predominant husbandry system across all groups was tie-stall. The average energy-corrected milk yield increased with increasing concentrate level, with L-TG showing the lowest and H-BS showing the highest milk yield. Age at first calving was lowest in H-BS when compared to all other systems, while numbers of lactations were higher in L-TG compared to H-BS. Feed efficiency (percentage of milk out of roughage) was significantly higher in L-TG and L-BS when compared to H-TG and H-BS. L-BS showed the poorest results for most of the welfare indicators such as lean cows, lesions and percentage of dirty animals. In conclusion, a higher concentrate level in diets does not lead automatically to lower animal welfare for dairy cows in alpine regions. Indeed, keeping high yielding breeds in extensive systems seems to be challenging. The dual-purpose breed TG showed some clear advantages in that calving interval was lower and the number of lactations greater.

Concentrate reduction and sequential roughage offer to dairy cows: effects on milk protein yield, protein efficiency and milk quality

An experiment was conducted during 6 weeks to evaluate effects of a reduced dietary level of protein-rich concentrates in a moderate dairy production system on cows’ performance, protein efficiency and milk quality including fatty acid profiles. Twenty-three lactating cows (Swiss Fleckvieh) were assigned either to a group receiving on average 2·4 kg/d individually fed concentrates (Prot+, n = 12) or to a group receiving no individually fed concentrates (Prot−, n = 11). All cows had ad-libitum access to a total mixed ration (TMR) mainly based on grass and maize silage, hay and little potatoes and soybean cake. In weeks 4–6 of the experiment, part of the hay was excluded from the TMR, and fed separately in the morning. Individual feed intake and milk yield were recorded during weeks 3 and 6 of the experiment; at the same time feed, faeces and milk samples were collected twice per week for analyses. Data were processed in linear mixed models. Omission of individual concentrates in Prot− was fully compensated by higher roughage intake in terms of dry matter. Crude protein (CP) and net energy intake was almost maintained. Despite a lower apparent CP digestibility in Prot−, the ratio of milk protein to ingested CP was the same in both groups, indicating a higher ruminal utilisation of degraded CP in Prot−. This corresponded with lower milk urea concentrations in Prot−. Milk quality was affected in terms of lower concentrations of linoleic and conjugated linoleic acid in milk fat of Prot−. Concentrations of odd- and branched-chain fatty acids in milk were increased in Prot−. Sequential offer of hay and TMR did not lead to considerable effects in intake, efficiency and milk quality. In conclusion, the results indicate that the efficiency of feed protein utilisation for milk protein is not impaired if concentrates are reduced in a moderate- to low-input dairy production system.