Revista de la Facultad de Ciencias
Agrarias. Universidad Nacional de Cuyo. En prensa. ISSN (en línea) 1853-8665.
Original article
Milk
production, age at first calving, and calving-to-conception interval in
Holstein, Brown Swiss, and Holstein x Brown Swiss cows
Producción
de leche, edad al primer parto e intervalo parto-concepción en vacas Holstein,
Pardo Suizo y Holstein x Pardo Suizo
Belén Lazzarini3,
Agustín Alesso4,
Javier Baudracco4,
1 Universidad Nacional de Rosario. Facultad de Ciencias
Veterinarias. Ovidio Lagos y Ruta 33 (2170). Argentina.
2 Universidad Nacional de Rosario. Carrera del Investigador
Científico (CIC). Maipú 1065 (2000). Argentina.
3 Universidad Nacional de Litoral. Facultad de Ciencias Agrarias.
Kreder 2805 (3080) Esperanza. Santa Fe. Argentina.
4 Universidad Nacional del Litoral-CONICET. FCA. IciAgro Litoral.
R. P. Kreder 2805. Esperanza 3080. Argentina.
* victoria.canete.c06815@fcv.unr.edu.ar
Abstract
The objective of
this study was to evaluate milk production, age at first calving, and calving
to conception interval in Holstein, Brown Swiss, and Holstein x Brown Swiss
crossbred cows within a pasture-based dairy system in Argentina. The increasing
global demand for more resilient and locally adapted dairy systems has led to a
renewed interest in crossbreeding to enhance both reproductive and productive
efficiency through heterosis. We analyzed data collected over 10 years
(2014-2023) from 647 first-lactation cows, including Holstein, Brown Swiss, and
Holstein x Brown Swiss crossbred cows. Data were examined using a mixed-effects
linear model with breed, season, and their interactions as fixed effect and
year as random effect. The results showed no significant differences in milk
production between breeds or seasons. However, a significant interaction
between breed and season was observed for the calving-to-conception interval,
with a shorter interval for crossbred cows during spring-summer (102 days), compared
to Holstein cows (156 days). This finding highlights a potential advantage of
crossbreeding in reducing open days during the warmest months, thereby
enhancing reproductive efficiency in pasture-based systems. This study suggests
that crossbreeding can be a viable strategy for improving reproductive
performance of dairy systems while maintaining similar milk yield compared to
the other breeds, particularly in grazing systems.
Keywords: dairy cows,
crossbreeding, Argentina, fertility, pasture-based systems, Holstein, Brown
Swiss
Resumen
El objetivo de este
estudio fue evaluar la producción de leche, la edad al primer parto y el
intervalo parto-concepción en vacas Holstein, Pardo Suizo y cruzas Holstein x
Pardo Suizo en un sistema lechero pastoril en Argentina. La creciente demanda
mundial de sistemas lecheros más resilientes y adaptados a las condiciones
locales ha generado un renovado interés por los cruzamientos para mejorar la
eficiencia reproductiva y productiva mediante la heterosis. Se utilizaron datos
recopilados durante 10 años (2014-2023) de 647 vacas de primera lactancia,
incluyendo vacas Holstein, Pardo Suizo y cruzas de Holstein x Pardo Suizo. Los
datos se analizaron utilizando un modelo lineal de efectos mixtos con la raza,
la estación y sus interacciones como efecto fijo y el año como efecto
aleatorio. Los resultados no mostraron diferencias significativas en la
producción de leche entre razas o estaciones. Sin embargo, se encontró una
interacción significativa entre raza y estación para el intervalo
parto-concepción, teniendo las vacas cruza un intervalo parto-concepción más
corto durante la primavera-verano (102 días) en comparación con las vacas
Holstein (156 días), destacando una ventaja potencial del cruzamiento en la
reducción de los días abiertos durante los meses más cálidos, mejorando así la
eficiencia reproductiva en los sistemas pastoriles. Este estudio sugiere que el
cruzamiento puede ser una estrategia viable para mejorar el rendimiento
reproductivo de los sistemas lecheros, manteniendo al mismo tiempo una
producción de leche similar a la de las demás razas, sobre todo en los sistemas
pastoriles.
Palabras clave: vacas lecheras,
cruzamientos, Argentina, fertilidad, sistemas pastoriles, Holstein, Pardo Suizo
Originales: Recepción: 30/10/2024
- Aceptación: 17/03/2025
Introduction
Holstein cows are
the predominant dairy cattle breed around the world (6) and also in
Argentina, where they account for 91.6% of the dairy cow population, followed
by Jersey (4.7%) and other breeds, including Brown Swiss (9,
10, 15, 20). Despite the predominance of Holstein, Brown Swiss cows offer
comparative advantages in milk composition, reproduction, and longevity, which
are beneficial in challenging environments for dairy production (2,
8). These characteristics could potentially improve efficiency in
dairy systems in regions with variable climatic conditions and variable forage
availability, such as in pasture-based systems.
As global demand
shifts toward more resilient and locally adapted dairy systems (18), farmers in
Argentina have shown renewed interest in crossbreeding. This practice aims to
improve the productive, reproductive, and economic efficiency of herds in
pasture-based systems (18, 23). Heterosis in
crossbred cattle can increase milk production up to 6.5% and enhance fertility
and disease resistance by 10% (5, 12, 13).
Crossbreeding
strategies worldwide integrate diverse production environments with different
genetic groups, leading to greater diversification and optimization of
productive systems (3, 21). Crossbreeding
Holstein and Brown Swiss cows can combine desirable traits from both breeds.
This study aimed to compare milk yield (MY305), calving-to-conception interval
(CCI), and age at first calving (AFC) in Holstein (H), Brown Swiss (BS), and
their crossbreed (H x BS) in a pasture-based dairy farm in Entre Ríos,
Argentina.
Materials
and methods
This study analyzed 10 years of records from a dairy farm at the
"Las Delicias" Agricultural School, located in western Entre Ríos
province (31°54’569’’ S, 60°25’253’’ W).
Database
The database
included records from herd tests conducted over a 10-year period from January
2014 to December 2023. The records covered 647 first-lactation cows, including
565 H, 53 BS, and 29 H x BS. Monthly herd tests were conducted each year.
Individual milk yield was recorded for each cow.
Dairy
herd and analized variables
In 2014, the farm
had 165 milking cows and 23 dry cows. By 2023, the herd consisted of 153
milking cows and 38 dry cows, all managed on the same milking platform within a
190-hectare area. The average annual milk production per cow in 2023 was 17
liters/cow/ day (3.9 fat% and 3.7% crude protein). The average diet consisted
of approximately 50% grazed pasture, primarily alfalfa and seasonal grasses,
while the remaining portion was supplemented with maize silage and concentrate
(13% or 16% CP, depending on nutritional requirements) during milking.
Variables
analyzed
Year of calving:
Year of first calving.
Season of calving:
Season in which the first calving occurred.
Age at first
calving (AFC): Cow’s age at first calving, expressed in days.
Milk yield adjusted
to 305 days (MY305): Milk produced in a 305-day period.
Calving-to-conception
interval (CCI): Days between calving and conception.
Statistical
analysis
Data were analyzed
using a mixed-effects linear model, with breed and season as fixed and year as
random effect. The model assumptions were verified by analyzing the residuals
and adjusting the variance structures by season, breed, or interaction when necessary.
The significance of the fixed effects was assessed using Type III ANOVA tables
with a significance level of 5%. Significant effects were further analyzed
using Tukey’s post-hoc test for pairwise comparisons. All statistical analyses
were conducted in the R statistical package (27) using the
"nlme" (25) and
"emmeans" (16) packages for
modeling and post-hoc comparisons, respectively.
Results
Table 1
presents the p-values obtained from the Type III ANOVA for the variables
analyzed. No significant effects for breed, season, or their interaction were
detected on AFC and MY305, indicating that these factors do not influence these
variables. However, for CCI a significant interaction between breed and season
was found, suggesting that the effect of breed on this variable depends on the
time of year.
Table 1. P-values
for the fixed effects in the models adjusted for the studied variables,
obtained from the marginal ANOVA (Type III) tables.
Tabla 1. Resumen
de los valores-p de los efectos fijos en los modelos ajustados por las
variables estudiadas, obtenidos a partir de las tablas de ANOVA marginal (Tipo
III).

1 Age at first calving. 2 Calving-to-conception
interval. 3 Milk
yield adjusted to 305 days.
1 Edad al primer parto. 2 Intervalo parto-concepción. 3 Producción de leche ajustada a 305 días.
Table 2
shows the estimated means for each variable by breed and season, along with
their standard errors and 95% confidence intervals.
Table 2. Estimated
means, standard errors, and 95% confidence intervals for Age at first calving
(AFC), calving-to-conception interval (CCI), and milk yield adjusted at 305
days in milk (MY305) for different breeds across Autumn-Winter and
Spring-Summer.
Tabla 2. Medias
estimadas, errores estándar e intervalos de confianza del 95% para la edad al
primer parto (AFC), el intervalo parto-concepción (CCI) y la producción de
leche ajustada a 305 días (MY305) para diferentes razas en otoño-invierno y
primavera-verano.

1 HxBS: Holstein x Brown Swiss; H:
Holstein; BS: Brown Swiss.
1 HxBS: Holstein x Pardo Suizo; H: Holstein; BS: Pardo
Suizo.
For CCI, the results show that H x BS cows have an average of
161 days in Autumn-Winter and 102 days in Spring-Summer. In contrast, H cows
had fewer days of CCI in Autumn-Winter (131 days) than in Spring-Summer (156
days). Regarding MY305, higher values were observed across all breeds for
lactations from cows that calved in Autumn-Winter compared to Spring-Summer,
although the differences were not statistically significant. For CCI no
significant effect of season or breed was found.
Discussion
This study
evaluated the effect of dairy breed on AFC, MY305 and CCI in primiparous cows
within a pasture-based system, emphasizing the need to select genotypes adapted
to local agroecological conditions for improved efficiency (1).
Milk yield. Our results
contrast with studies conducted in intensive systems where H, BS y H x BS
produced higher milk yield. Dechow et al. (2007) reported that H x
BS cows performed similarly to pure H cows in confined systems, exceeding
11,000 liters per lactation. However, in pasture-based systems, forage
availability and seasonal variations limit potential milk production (17,
24). In our study, despite the higher productive potential, H cows
did not outperform crossbred, likely due to these constraints. A previous study
(31) conducted in the
same production system (Agricultural School "Las Delicias") but
during an earlier period (2007-2013), reported adjusted 305-day milk yield of
7162±856 liters (23.5 liters per cow per day) for H cows, 6168±1046 liters
(20.2 liters per cow per day) for BS cows, and 6743±1048 liters (22.1 liters
per cow per day) for H x BS cows, with significant differences among breeds.
The findings of the previous study suggest that environmental conditions,
particularly management and feeding practices, may have contributed to higher
milk yields, especially among Holstein cows, which produced significantly more
milk.
Age at first calving (AFC). Previous research
highlights the benefits of hybrid vigor in improving the reproductive
efficiency of crossbred dairy cows. García-Peniche et
al. (2006) found that crossbred cows (H, BS and Jersey) tend to reach
reproductive maturity earlier, offering farmers a significant economic
advantage by reducing rearing costs and accelerating the return on investment.
However, our study found no significant effect of breed on AFC.
Management and
agroecological impacts become evident when comparing our results with previous
studies (19). Hutchison et al. (2017), found that H cows
in intensive systems reach first calving at an average of 24-25 months. In
contrast, in our study, H and BS cows took longer to reach reproductive
maturity, suggesting that pasture-based conditions impose additional
constraints on the growth and development of heifers. This difference
highlights the importance of adapting both nutritional and genetic management
to local conditions to optimize reproductive efficiency (22).
Calving-to-conception
interval (CCI) H x BS crossbred cows in our study had shorter CCI during the
Spring-Summer than pure H cows, consistent with previous finding on their
superior reproductive performance in warm months (7,
28, 29). In Argentina´s main dairy region cows are exposed to heat
stress for at least 100 days per year, primarily in spring and summer (15). Thus, a shorter
CCI is advantageous in grazing systems, enhancing reproductive efficiency and
reducing unproductive periods. Similar trends have been reported by Blöttner
et al. (2011a) and Prendiville et al. (2010), confirming higher
pregnancy rates in crossbred cows.
The improvement in
reproductive efficiency observed in H x BS crossbred cows could be attributed
not only to hybrid vigor but also to the reduction of negative effects
associated with inbreeding depression, which commonly affects pure H cows in
intensive systems (5). This enhanced
reproductive efficiency may be explained by the greater adaptability of
crossbred cows to environmental fluctuations, such as forage quality and
seasonal variations in temperature (30).
Conclusions
While no significant differences were observed in age at first
calving (AFC) and 305-day milk yield (MY305) among breeds, the significant interaction
between breed and season in calving-to-conception interval (CCI) suggests that
both environmental conditions and genetic factors influence reproductive
efficiency, particularly in H x BS cows during the warmest period of the year.
Future studies could focus on further exploring the environmental and genetic
factors that drive the observed interactions between breed and season,
particularly in relation to optimizing reproductive efficiency in pasture-based
systems.
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Author
contributions
JB:
Conceptualization, Writing - review & editing; PRM: Supervision,
Methodology, Writing -; VC: Data curation, Writing, review & editing; BL:
Review & editing; AA: Statistical analysis.
Conflicts of
interest
The authors declare
no conflicts of interest.
Declaration of
Funding and acknowledgments
Al Técnico
Agropecuario Marcelo Exner y a la Escuela Agrotécnica “Las Delicias”, por su colaboración en la
recopilación de información y apoyo incondicional para la realización de este
trabajo.
A data availability
statement
The data that supports this study will be shared upon reasonable
request to the corresponding author.