Horse Preference for Alfalfa-Grass Hay
Harvested in the Afternoon or Morning

L.C. MacKay1, H.F. Mayland2, and W.P. MacKay3

1Franklin High School, El Paso, TX, 79912; 2USDA-ARS, Kimberly, ID, 83341;
3University of Texas, El Paso, TX, 79968


Cattle, sheep, and goats, prefer forage cut in the afternoon to that cut in the morning. This preference has been attributed to the presence of more sugar in the afternoon than morning forage. However, no quantitative studies have been reported for horse responses. We chose to test horses’ preference for afternoon (PM) vs. morning (AM) cut alfalfa-grass hay grown in southeastern Montana. Mixed alfalfa-grass (alfalfa = 15 % bloom) was cut on 5 July 2002 at 1900 hr and again the next morning at 0700 hr using a swather with conditioner. Hay was air dried for 24 h and baled into 300 kg round bales. Bales were placed on palettes, tarped, and stored in a metal hay shed. Hay consisted of 70% Grimm alfalfa and 30% Fairway crested wheatgrass. Five kg of both hays (AM- and PM- cut) were offered ad libitum to each of five American Quarter horses for 10 minutes during the morning and afternoon. Both feeding order and position of feed buckets were randomized at each feeding. Dry matter intake was determined by weighing before and after feeding. Four samples of each bale were dried in a convection oven (60° C) and ground into a fine powder. One gram of powdered hay was combined with nine milliliters of distilled water, boiled for five minutes, and vacuum filtered through Whatman #1 qualitative paper. Sugars in the filtrate were determined using a hand held Bausch and Lomb 400SD refractometer having range of 0 - 60%. Data were tested with analysis of variance. Horses preferred the PM-cut hay by eating twice as much of the PM- as of the AM-cut hay (P = 0.001). The sugar concentration was 170 mg/g greater in the extract from the PM-cut than from AM-cut hay (P = 0.04). Horses are able to identify forage having greater sugar concentrations and will eat larger quantities of this hay.


Ganados, ovejas y cabras prefieren forrage cortado por la tarde (PM) que el forrage cortado por la mañana (AM). Esta preferencia ha sido attribuída a la presencia de más azúcar en el forrage de la tarde que en el de la mañana. Sin embargo, no sean reportado estudios sobre la reacción de los caballos. Decidimos evaluar la preferencia de los caballos por el heno de alfalfa y pasto cultivado en sudeste de Montana y cortado por la tarde, comparado con el cortado por la manana. El heno de alfalfa y pasto (alfalfa = 15% en florescencia) fue cortado el 5 Julio 2002 a las 19:00 horas y al día siguiente a las 07:00 de la mañana. El heno fué secado al aire por 24 horas y atado en rollos de 300 kg. Los rollos fueron colocados en un corbertizo de metal. El heno consistía de 70% de alfalfa Grimm y 30% de pasto Fairway. Cinco kg de ambos henos (cortado en PM y AM) fueron ofrecidos ad libitum a cada uno de cinco caballos por diez minutos, por la mañana y por la tarde. El orden y la posición de los baldes de forrage fueron seleccionados al azar en cada comida. La cantidad consumida fué medida pesando el heno antes y después de cada comida. Cuatro muestras de cada rollo fueron secadas en un horno de convección (60° C) y molidas en polvo fino. Un gramo de este polvo de heno fué combinado con nueve ml de agua destilada, herbido por cinco minutos, y filtrado con una aspiradora usando papel de filtro Whatman #1. Azúcares en el filtrado fueron determinados usando un refractómetro manual Bausch and Lomb 400 SD con un rango 0-60%. Los datos fueron analizados usando ANOVA. Los caballos prefirieron el heno cortado por la tarde y comieron el doble comparado con el heno cortado por la mañana (p = 0.001). La concentración de azucares en el heno (PM) tiene 170 mg/g más que el heno de la mañana (p = 0.04). Los caballos pueden identificar el forrage con mayor concentración de azúcares.






Table 1. Climate data for the days before and after hay was cut
(USBR, 2003). ‘Ranch rainfall data are from ranch records.
Dates in July 2002
Low Temp (° C)  
High Temp (° C)  
Ranch, ppt. (mm)  
Solar (langleys)  





Table 2. Intake and sugar concentration in the PM- and AM-cut hays.
Hay Intake Per Feeding
Sugar in Hay Extract
PM-Cut Hay
630 g
AM-Cut Hay
310 g
PM vs AM Cut
P = .001
P = .001




Personal Vitae of Sr. Author
I recently graduated (2003) from Franklin High School in El Paso, TX. I was selected as Franklin All-Girl and was invited to give a speech for our graduation commencement exercises. I was the secretary for the Math Honors Society and competed in many science competitions in the southwest region. Last year, I was a finalist at the Intel International Science and Engineering Fair in Louisville, KY. This year, I was invited to the National Junior Science and Humanities Symposium in Colorado Springs, CO, to present my research. I enjoy riding horses, hiking and camping. I also work as a horseback riding instructor for Therapeutic Horsemanship of El Paso, an organization that specializes in hippotherapy for physically- and mentally-disabled students. My summers are spent on the family ranch in southeastern Montana, where I am able to ride to my heart's content. This is where I developed my love for the land and an interest in agriculture. I attended Montana Range Days for three years and was awarded first place this past summer.
I became interested in PM-harvest of hay the summer before my sophomore year. I was brainstorming with a family friend who has been instrumental in catalyzing many young peoples' interests in agriculture, and she mentioned that she had access to a refractometer, which would measure the percent sucrose in a plant. Thus, I started my research and consulted with Dr. Hank Mayland, from Kimberly, ID, who has mentored and inspired me to continue answering my own questions for three years.
My future plans include obtaining a double major in Range and Animal Science from New Mexico State University. I would like to continue doing research and see where my heart and opportunities lead me.


Literature Cited
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