Effect of Cutting Date on Digestibility and Intake of Irrigated First‐Crop Alfalfa Hay¹

Abstract

Delayed cutting during the practical harvesting season of first‐growth forages raised in humid climates has resulted in a linear decline in the digestibility component of nutritive value. This study considered the effect of cutting date upon the digestibility and intake components of nutritive value of first growth alfalfa (Medicago sativa L.) raised under irrigated conditions at two altitudes in Utah and Montana. Duration of the study was 5 years with harvests occurring over ranges of 23 to 62 days. Intake and digestibility by total collection of each hay were determined with four sheep. Digestibility was determined during three years at both ad libitum and a controlled feeding level. Hays were harvested at Huntley, Montana for the first two years and at Logan, Utah for the remaining three years. The variety ‘Ranger’ was used during the first four years and ‘DuPuits’ and ‘Lahontan’ varieties were compared during the last year. Daily intake of dry matter decreased 0.21 g/kg BW¾ for each day of delay with large variations in rate of change for different year‐variety sets of data. Digestibility of the dry matter decreased approximately 0.28 percentage units per day for both Huntley and Logan hays, but Ranger alfalfa was about six percentage units more digestible on June 10 at Huntley than at Logan. Correlations between dry matter and energy digestibilities and between dry matter and organic matter digestibilities were 0.98 and 0.97, respectively. Crude protein concentration declined 0.20 percentage units per day. Digestible protein concentration of alfalfa forage can be expressed as a function of crude protein concentration by Y = −4.15 + 0.97X with r = 0.98.

Impact of Insect Feeding on Alfalfa Regrowth: A Review of Physiological Responses and Economic Consequences

“…Potential feed intake, which is estimated from cell-wall concentration and believed to have a more significant negative impact on animal utilization than reduced digestibility, is reduced with phenological advancement (Sanderson and Wedin, 1988;Troelsen and Campbell, I 959). Indeed, reduced intake may account for two-thirds of the total variability in animal performance (Byers and Ormiston, 1962;Anderson et al, 1973;Waldo and Jorgensen, 1981). Each day that spring growth of alfalfa progresses beyond the vegetative stage of development, a loss of potential feed intake amounting to 0.2: I g (forage wt.)…”

Forage production and quality of serradella in mild winter areas in north‐west Spain

“…The changes in forage quality between the April and May harvests showed an overall average decline of 0.71 g kg *1 d" 1 in CP and of 1.42 g kg 1 d" 1 in IVOMD, whereas the ADF rose by an average of 1.5 g kg" ' d~ '. The decline in CP contents (with serradella lines advancing from vegetative to flowering stage) was lower than the 2.0 to 2.8 g kg" 1 d"' reported by Buxton et al (1985) Anderson et al (1973) for alfalfa and by Buxton et al (1985) for alfalfa, birdsfoot trefoil, and red clover, although they used different in vitro digestibility methods. These slow reductions in the forage quality of the Ornithopus species, with advancing maturity, were also observed by Gladstones & Loneragan (1975) in Australia and Lapeyronie (1982) in northern Africa.…”

Changes in the baseline of the Crop Water Stress Index for lucerne (Medicago sativa) over 3 years

“…Crop maturity is a pattern of physiological changes. There is evidence that digestible dry matter and total digestible nutrients change from the first year of production to the second (Smith 1964: Baumgardt & Smith 1962: Anderson et al 1973. Sharratt et al (1987) found that lucerne responded differently to temperature, solar radiation, and wind speed as the stand aged.…”