The aim of this study was twofold: first, to evaluate the influence of body weight on the efficiency of dairy cows, and second, to analyze the current state of dairy cattle populations as part of the Austrian Cattle Breeding Association's Efficient Cow project.
Data of Fleckvieh (FV, dual-purpose Simmental), Fleckvieh
In addition to routinely recorded data (e.g., milk yield, fertility), body weight, body measurements, body condition score (BCS) and individual feed information were also collected. The following efficiency traits were considered: body weight efficiency as the ratio of energy-corrected milk (ECM) to metabolic body weight, feed efficiency (kilogram ECM per kilogram dry-matter intake) and energy efficiency expressed as the ratio of energy in milk to energy intake.
The relationship of milk yield to body weight was shown to be nonlinear.
Milk yield decreased in cows above the 750 kg body weight class for HF, BS
and FV
The average body weight of the breeds studied (FV 722 kg, BS 649 and HF 662 kg) was in the optimum range. FV was located at the upper end of the decreasing segment.
In conclusion, an optimum body weight range for efficiency does exist, due
to the nonlinear relationship of milk yield and body weight. Specialized
dairy breeds seem to respond more intensively to body weight range than
dual-purpose breeds, due to the stronger curvature. Cows with medium weights
within a population are the most efficient. Heavy cows (
Over the last decades, milk performance has increased dramatically and resulted in a decline in fertility, vitality and longevity (Knaus, 2009). This development has reduced cows' cost effectiveness. In the USA, Bavaria (Germany) and Austria (Knaus, 2009), the number of completed lactations has dropped under the calculated critical threshold of four parities (Essl, 1982). In Austria, there have been efforts to stop this trend, including introducing a breeding value for longevity in 1995 and a joint genetic evaluation in Austria and Germany in 2002 (Fuerst and Egger-Danner, 2002). Cows' body size is also increasing. In the USA, Holstein cows were selected directly for body size to some extent, on the assumption that larger cows are able to produce more milk (Hansen, 2000). In Bavaria (Germany), increasing body size in Fleckvieh (dual-purpose Simmental) and Brown Swiss (BS) has been negatively connected to longevity (Krogmeier, 2009). In 1966, a long-term experiment with Holstein (HF) cows at the Northwest Experiment Station, University of Minnesota, concerning cow size was initiated and resulted in several studies (e.g., Mahoney et al., 1986; Hansen et al., 1999; Becker et al., 2012). The selected line became larger and heavier but had higher health costs. Studies, for example Brown et al. (1977), have shown that the highest milk yield was reached in the medium body weight range; large and heavy cows were not found to be at an advantage, neither in health and fertility traits, nor in milk production. The relevant genetic relationship between milk yield and body weight is difficult to quantify and varies due to the distorting effects of body tissue mobilization and a lack of sufficient data, but it is assumed to be positive (Veerkamp, 1998). However, heavier cows have to produce more milk to be as efficient as lighter cows to dilute the negative effect of their high body weight and therefore increased maintenance requirements (Hansen et al., 1999; Steinwidder, 2009). In countries like Ireland and New Zealand, where dairy cows are bred for the efficient use of pasture, animals are lighter and have a higher body condition but produce approximately only half of the milk yield (Knaus, 2016).
The Federation of Austrian Cattle Breeders (ZAR) initiated the project Efficient Cow in 2012 to develop efficiency traits for Austrian cattle breeding. Within this framework, the aims of this study were (1) to examine the influence of body weight and genotype on different efficiency parameters for milk production, (2) to clarify if an optimum body weight for highest efficiency exists and to describe the current state of the examined dairy cattle population, and (3) to give recommendations concerning body weight in cattle breeding.
During a 1-year recording period in 2014, data from 3628 Fleckvieh (FV)
and FV
The handling of forage analyses (VDLUFA, 1976), nutrient content of concentrate (DLG, 1997) and calculation of energy content of forage (GfE, 2001) have been described in detail in a previous article by Ledinek et al. (2019a). The laboratory for feed analyses of the Chamber of Agriculture in Lower Austria analyzed the forage samples using Weende analysis and the method described by Van Soest et al. (1991). Dry-matter intake (DMI) was estimated because comprehensively measuring feed intake on-farm was not feasible (Gruber et al., 2004; Ledinek et al., 2016). This situation provided the opportunity to develop novel strategies for recording diet composition information on-farm. Feeding system and diet composition were also considered in the feed intake prediction model. The prediction model selected for this study was found to be the most valid and accurate model in a comparison of four up-to-date models (Jensen et al., 2015). A detailed description of recording diet information, feed intake estimation and the results of diet composition can be found in Ledinek et al. (2016) and Ledinek et al. (2019a). Energy-corrected milk (ECM) was calculated according to the recommendations of GfE (2001). Body condition was evaluated using the five-point system by Edmonson et al. (1989).
As recommended by Berry and Pryce (2014), efficiency parameters were
calculated as the ratio between output and input and named after the input
parameter in the current study. The estimation of feed intake resulted in
the exclusion of residual feed intake. Body weight efficiency was calculated
as kilogram ECM per kilogram metabolic body weight (BW
The data set during lactation included 37 967 records (milk performance recordings), 161 farms and 6098 cows.
Combined genotype–body-weight classes were established to cover differing
body weight ranges within the genotypes. Body weight classes were set at
50 kg intervals from 450 to 1000 kg. Cows with a body weight between
Fleckvieh (100 % FV ancestry, 1575 cows), Fleckvieh with an average
of 25 % RH genes (FV
The stage of lactation consisted of twelve 28 d stages from 1 to 336 d in milk (DIM).
The following final model for dependent traits (e.g., DMI, BCS, efficiency
traits) was used:
Traits were analyzed using PROC MIXED of SAS 9.4 (SAS, 2015), the restricted maximum likelihood (REML) method, the Kenward–Roger method and the covariance structure Variance Components (VC) causing the smallest Akaike information criterion.
Table 1 contains BCS, milk production, estimated DMI and energy intake,
while DMI per kilogram body weight and efficiency parameters can be found in Table 2. The root mean square errors are shown separately (Table 3). Apart from
energy content of forage on BCS (
Effect of genotype
Effect of genotype
Root mean square error of efficiency and production traits.
Average milk production, DMI and efficiency parameters increased for the most part continuously, together with rising RH genes from FV to HF as previously described in detail (Ledinek et al., 2019a, b). BS had a lower feed and energy efficiency than FV. For most traits, BS came in between the two genotypes FV and HF.
Feed and energy intake increased up to 750 kg body weight and then tended to
stagnate or even to decline, especially in the genotypes with a high
proportion of specialized dairy breeds (FV
This pattern was also observed for efficiency parameters, although body
weight efficiency differed from feed and energy efficiency. HF produced the
most ECM per kilogram body weight in the 500–650 kg range; BS does so in the lightest
classes at 450–650 kg. In contrast, the efficiency of FV and FV
Although breed differences in feed and energy efficiency vanished again at a weight of 800 kg, peak efficiency shifted to cows with medium weight. The optimum range of BS and HF was 550–700 kg, peaking between 550 and 650 kg. Contrary to this, the efficiency of FV remained steady from 500 to 750 kg, with the highest efficiency at 600 kg. Efficiency declined increasingly, and was observable starting from the body weight classes of 750–800 kg.
Body condition (Fig. 1) rose in a nearly linear fashion with increasing body weight. In the optimum range, FV had a BCS of 2.63–3.49 points, HF had one of 2.28–2.76 points and BS one of 2.64–3.05 points.
Effect of body weight on feed intake, milk production, BCS, body
weight efficiency, feed efficiency and energy efficiency (LE: energy in
milk) of Brown Swiss (BS), Fleckvieh (FV), the selected FV groups with
increasing Red Holstein (RH) genes FV
The nonlinear relationship between milk yield and body weight and the
stronger curvature of the specialized dairy groups (FV
In the current study, body weight and milk yield were phenotypically
correlated to a low degree of 0.12. Due to the nonlinear relationship, it
would be a mistake to assume a failing connection between the two traits.
Enevoldsen and Kristensen (1997) found nearly nonexistent negative and
positive correlations within Red Danish
Published results on genetic relationships vary as well. In earlier studies
(Mason et al., 1957; Hooven et al., 1968), positive relationships were
reported, while Veerkamp (1998) revealed a range between
In the current study, the phenotypic correlations between body weight and
efficiency were
The finding that having medium-weight cows in a population is optimal has also been confirmed by much older studies (Hooven et al., 1968; Miller and Hooven, 1969; Brown et al., 1977). Hansen et al. (1999) compared lighter and heavier HF lines and concluded that due to frequent problems in health and fertility of heavy cows, an optimum body weight range may exist. As Fig. 1 shows, dry-matter intake and milk yield behave differently with regard to their correlation with body weight. Dry-matter intake does increase with increasing body weight over its total range but to a decreasing extent. Contrary to this, milk yield declines in high body weight classes. As a consequence, efficiency parameters reach their maximum not at the lowest or highest body weights, but somewhere in between, more towards the lower end of the weight range. The somatotropic axis controls nutrient partitioning between milk production and body tissue, mainly through the hormones somatotropin and the insulin-like growth factor (Lucy, 2000; Lucy et al., 2009). A high potential for milk production reduces body condition within and among breeds (e.g., Buckley et al., 2000; Dillon et al., 2003; Ledinek et al., 2019b). Consequently, the precondition for a large and heavy body (high body weight and BCS) is the genetic potential for partitioning nutrients into growth and body tissue to a higher extent. This explains why cows in the heavier body weight classes with concurrent higher BCS (Fig. 1) produced less milk relative to their weight. If they produced relatively more ECM, they would be large-framed dairy types with low BCS. Veerkamp (1998) described a negative genetic association between milk yield and BCS. After the genetic adjustment for BCS, the moderately positive genetic association between milk yield and body weight was in line with the positive relationships between milk yield and body size measurements.
In the current study, the higher the gene proportion of specialized dairy
breeds, the more the genotypes responded to the range of body weight.
Corresponding results were found in a study by Gruber et al. (2017) based on
data from German and Austrian research institutes. Somatotropin and the
insulin-like growth factor control many aspects of lactation, growth and
fertility in cattle (Lucy, 2000). The selection for milk production
changed the nutrient partitioning mechanisms (Lucy et al., 2009) due to the
high metabolic priority given to milk production (Bauman and Currie, 1980).
This suggests that the relationship between feed intake, ECM and body weight
is not the same in dual-purpose and dairy breeds due to differing nutrient
partitioning as shown in the current study. Resources like nutrients and
energy are primarily put into performance in high-yielding dairy cows
(Huber, 2018). It is not only inadequate management (Huber, 2018) but also an
inadequate nutrient intake in the first third of lactation (Bauman and
Currie, 1980) that limit available resources and make nutrients scarce,
especially for maintenance (body, BCS), fertility and health (Huber, 2018).
In specialized dairy cows, a small shift in priority towards body weight and
BCS along the body weight range probably has a stronger effect on nutrient
partitioning towards milk yield. This explains the increasing dependency of
efficiency on body weight with increasing specialization for milk production
in the current study. During lactation, high-yielding cows have higher
levels of growth hormones, nonesterified fatty acids (NEFAs) and
These indications led to the assumption that the increasing body weight classes within a breed may reflect the spectrum of potential in dairy traits, with a higher sensitivity of dairy types to body weight range. However, it must be emphasized that for animals with a low BCS, it was not possible to differentiate between light dairy types and cows that had previously mobilized large amounts of body tissue.
Nevertheless, the groups with a higher proportion of specialized dairy
breeds only benefited from their superiority in milk production in the
medium body weight range as compared to the dual-purpose types. The average
body weight of the FV groups with an average of up to 25 % RH genes was
between 722 and 729 kg, and that of HF and BS was 662 and 649 kg, respectively, in the
overall analysis (Ledinek et al., 2019a, b). Therefore, the lighter
specialized dairy breed groups were actually at the peak of their optimum
nutrient efficiency, while the FV groups with an average of up to 12.5 %
RH genes as dual-purpose types were located on the upper end of the
decreasing segment. FV
The relationship between milk yield and body weight was found to be nonlinear. Heavy and very light cows produced less milk than cows of medium body weight. The nonlinear relationship between milk production and body weight resulted in an optimal body weight for highest feed and energy efficiency in the medium body weight range of the population. The specialized dairy breeds seemed to respond more intensively to body weight range than dual-purpose breeds. Their superiority in feed and energy efficiency was only observable in the medium body weight range within populations. In Austria, HF and BS have currently reached their optimum of nutrient efficiency. FV is still within the optimum range of body weight but is reaching the top end. As optimum body weight efficiency is located towards the lighter body weight range, all genotypes are too heavy as to be at the peak of optimum.
Therefore, further increases in body weight of all breeds with regard to nutrient and body weight efficiency cannot be recommended. A broader definition of efficiency including additional aspects like health, fertility or fattening potential should be investigated in the future.
The data sets analyzed during the current study are not publicly available as information contained therein could compromise the privacy of third parties.
All authors made substantial contributions to the project Efficient Cow and paper preparation. FS and MM programmed the database for on-farm data collection. KZ and FS coordinated the data collection. MR, KK and LG supported ML during data processing. ML analyzed the data in close collaboration with LG. ML prepared the paper with support from LG and BFW. CED was project manager. BFW, CED and LG advised ML during the project.
The authors declare that they have no conflict of interest.
The authors gratefully acknowledge Kathleen Knaus for language editing.
This research has been supported by the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (grant no. 100861), the Federal States of Austria (grant no. 100861), the federations of Austrian Fleckvieh, Brown-Swiss and Holstein (grant no. 100861), and the Federation of Austrian Cattle Breeders (grant no. 100861).
This paper was edited by Antke-Elsabe Freifrau von Tiele-Winckler and reviewed by Korinna Huber and one anonymous referee.