ABSTRACT The intensification of dairy production systems has resulted in a higher generation of waste. The aim of this study was to evaluate the impact of different doses of farm dairy effluent (FDE) applied to the soil on aerial biomass production, persistence and chemical composition of alfalfa pastures, in Santa Fe province, Argentina. The study was conducted in four randomized complete blocks with four treatments (FDE doses): 0 m3 ha-1 (T0: without FDE), 82 m3 ha-1 (T1: low rate), 151 m3 ha-1 (T2: medium rate) and 282 m3 ha-1 (T3: high rate). The soil application of FDE increased the total aerial biomass produced (ABP) but reduced the persistence of plants. Total nitrogen (Nt) of alfalfa was significantly higher, but phosphorus (P) concentrations did not vary after the application of FDE to the soil . Ca and Mg concentrations in plants were lower in T3 compared to T0, which can be explained by the imbalance produced in the soil after FDE was applied, presenting high levels of Na, K and NH4-N but low levels of Ca and Mg. Soil application of FDE on alfalfa pastures must be carefully planned in terms of composition and amount to be applied in order to increase biomass production, prevent the decrease in persistence, and control changes in the mineral composition of plants.

ABSTRACT The productive characterization of livestock systems is a key aspect when designing management plans aimed at increasing beef production in a region. The objective of this work was to characterize technified cow-calf systems of the north region of the Santa Fe province, Argentina, and to analyze the correlation between the variables identified and the effect on beef production. Sixteen variables related to structure, technology, and productive and reproductive efficiency were assessed in 27 farms. Descriptive statistics and multivariate analyzes were performed at a significance level of p ≤ 0.05. Stocking rate (cows ha1), weaning rate (%) and beef production (kg LW ha1 year-1) of the surveyed farms were 15, 38 and 84% higher, respectively, compared with typical systems of the region. The higher area with cultivated species was positively correlated with pregnancy rate (p = 0.0269) and weaning rate (p = 0.0051). Supplementation level of cows (p = 0.0259) was positively associated with stocking rate (cows ha-1). Furthermore, stocking rate (cows ha-1) correlated positively with higher calf production (kg LW ha-1 year-1; p < 0.0001) and total beef production (kg LW ha-1 year 1; p < 0.0001). Technified farms showed a better productive performance compared to that of typical cow-calf systems in the region studied.

RESUMEN La caracterización productiva de sistemas ganaderos es clave para diseñar planes de mejora en sistemas de producción de carne de una región. El objetivo de este trabajo fue identificar características productivas de sistemas de cría tecnificados del norte de la provincia de Santa Fe en Argentina, y analizar la relación entre las variables identificadas y su efecto sobre la producción de carne. Se relevaron 16 variables de estructura, tecnológicas y de eficiencia productiva y reproductiva en 27 establecimientos. Se realizaron análisis del tipo descriptivo y multivariado, con un nivel de significancia p ≤ 0,05. La carga animal (vacas ha1), el porcentaje de destete y la producción de carne (kg PV ha1 año1) de los sistemas tecnificados evaluados fueron un 15, 38 y 84% superiores, respectivamente, respecto a sistemas típicos de la región. La mayor superficie con especies cultivadas se correlacionó positivamente con los porcentajes de preñez (p = 0,0269) y destete (p = 0,005). El nivel de suplementación de las vacas (p = 0,0259) se asoció positivamente con la carga animal (vacas ha1). A su vez, la carga animal (vacas ha1) correlacionó positivamente con una mayor producción de terneros (kg PV ha1 año1; p < 0,0001) y producción de carne total (kg PV ha1 año1; p < 0,0001). Los predios tecnificados presentaron mejores indicadores productivos que los predios de cría típicos de la región estudiada.

ABSTRACT Dairy production in Argentina has been intensified, but dairy farms are facing problems to increase productivity. This work aimed to identify the major constraints on milk production in dairy farms of the North East region of Buenos Aires province, Argentina. A survey was conducted to collect production data from 29 dairy farms. The major constraints were: insufficient water provision (there is one water trough every 19 ha), and insufficient natural and artificial shade for cows (1.8 and 2.9 m2 cow-1, respectively); old dairy facilities (dating back 21 years) and lack of investment in milking equipment; long milking times (3.3 hours per milking); deficiencies in soil phosphorus (9.3 mg kg-1) and sulphates (11.7 mg kg-1); presence of nitrates in cattle drinking water and inadequate effluent storage and distribution. According to the correlation analysis performed, it can be inferred that dairy farms that increased land productivity by increasing herd size did not improve farm infraestructure to meet new requirements. Investment to cope with the problems detected might increase milk production and improve the sustainability and profitability of dairy farms.

RESUMEN La producción de leche en Argentina se intensificó, pero las fincas lecheras enfrentan limitantes para incrementar su productividad. El objetivo del presente trabajo fue detectar las principales limitantes a la producción de leche en las fincas lecheras de la región Noreste de la provincia de Buenos Aires, Argentina. Se confeccionó una guía para relevar datos productivos de 29 fincas lecheras. Las principales limitantes detectadas fueron: cantidad insuficiente de agua de bebida para el ganado (1 bebedero cada 19 ha) y de sombras naturales y artificiales (1,8 y 2,9 m2 vaca-1, respectivamente); niveles deficientes de fósforo (9,3 mg kg-1) y sulfatos (9,3 mg kg-1) en el suelo; instalaciones de ordeño antiguas (21 años) y falta de inversión en equipos de ordeño; excesivo tiempo de ordeño (3,3 h por ordeño); presencia de nitratos en el agua de bebida del ganado; y almacenamiento y distribución de efluentes inadecuado. Se infiere, a partir del análisis de correlaciones realizado, que las fincas que incrementaron la productividad a partir del incremento de la cantidad de vacas no incrementaron en similar medida su infraestructura. Las inversiones tendientes a superar las limitantes detectadas podrían permitir incrementos en la producción de leche y mejorar la sustentabilidad y rentabilidad del negocio lechero.

ABSTRACT Variations in milk and concentrate feed prices and the effect of climate on crop production affect productivity and profitability of dairy systems. The objective of this study was to evaluate productivity and economic results, and assess the risk of different dairy systems in the Central-Northern region of Argentina. Alternative dairy systems (other than the traditional system of this region) were studied, evaluating the effects of increases in stocking rate and use of supplementary feed, as well as the effect of using different feeding systems on productivity and profitability. Two mathematical models were used in this analysis: one model to predict crop and pasture production, and the other to evaluate the performance of the whole dairy system. Deterministic and stochastic simulations, i.e., with random variation in milk and concentrate feed prices, and crop yield, were performed. Results showed that the current production system of this region is not profitable. The alternative systems with higher stocking rate and supplementation resulted in higher milk production per hectare and improved economic results. However, intensification of the system, through increases in stocking rate and supplementation resulted in an increased risk. Milk and concentrate feed prices had more impact on the economic results than climate.

RESUMEN Las variaciones en el precio de la leche y de los alimentos concentrados y el efecto del clima sobre la producción de cultivos afectan la productividad rentabilidad y riesgo de los sistemas lecheros. El objetivo del estudio fue investigar la productividad, el resultado económico y el riesgo de diversos sistemas de producción de leche en la región Centro-Norte de Argentina. Se investigaron sistemas lecheros alternativos al sistema representativo de la región, explorando el efecto de incrementos en carga animal, incrementos en suplementación con alimentos concentrados y el efecto de utilizar diferentes sistemas de alimentación sobre la productividad y la rentabilidad. El enfoque elegido para el análisis fue la simulación con el uso de dos modelos matemáticos: uno para predicción del rendimiento de cultivos y otro para evaluación del sistema lechero completo. Se realizaron simulaciones determinísticas y estocásticas, i.e., con variación aleatoria del precio de la leche, de los concentrados y el rendimiento de los cultivos. Los resultados muestran que el sistema actual de la región no es rentable. Los sistemas alternativos con mayor carga animal y mayor suplementación resultaron en mayor producción de leche por hectárea y mayor resultado económico que el sistema regional actual. Sin embargo, la intensificación a partir del incremento de la carga animal y de la suplementación aumentó la exposición al riesgo. El efecto de la variación de precio de leche y concentrado fue mayor que el efecto del clima sobre el resultado económico.

The objectives of the present study were to develop a methodology that implies the use of an electronic spreadsheet to calculate the financial losses of involuntary days open (IDO; every additional day open beyond an optimal calving-to-conception interval) and to show an example of the cost of days open using the proposed methodology. The costs accounted for in the methodology were: milk yield loss, calf crop loss, additional reproductive interventions, and cow replacement costs due to infertility. An example for Argentinean dairy cows in grazing year-round calving systems is presented. Results suggest that milk yield loss and cow replacement due to infertility are the main components determining the final cost of the delayed pregnancy. The methodology presented in this study is simpler than previous methodologies, and can be applied in a wide range of scenarios, using different cow types and regional costs.