Factors Influencing Lactation Performance of Range Beef and Dairy-Beef Cows

Abstract

An investigation was carried out to study factors influencing milk yields and milk constituents among range cows. June and September measurements of milk yield and constituent percentages of butterfat (BF), protein (PT) and lactose (LT) were taken using 206 and 222 cows in 1976 and 1977, respectively. The cows, representing four beef and dairy-beef breed groups, were from the University of Alberta beef herd and ranged in age from 2 to 10 years. Regression of milk yield on calf age (CA) demonstrated a negative association over the lactation period measured, although regression coefficients were not statistically significant. Associations between all constituent yields with CA were negative. However, regression coefficients of June and September constituent percentage variables on CA indicated a more positive association as lactation progressed. Cow weight loss during gestation, cow weight at calving and ADG during lactation did not account for a significant proportion of the variation in either milk or constituent yields or constituent percentages over and above main effects. The association between cow ADG during lactation and all yields was negative although not statistically significant. Calf birth-weight was positively associated with all yields, and showed negative association with BF% and PT%. Calf average daily gain measured from birth to September was highly associated with yields of milk and constituents, declining from June to September. Its association with BF% and PT% was negative. Cow calving interval was introduced as a possible factor influencing milk yields of 3- and 4-yr-old and mature cows. Its association with lactation performance was however, not significant. Key words: Lactation, range cows

Milk Yield and Composition in Beef Cows and Their Effect on Cow and Calf Performance in Two Environments

“…Although published results vary considerably on the relationship of sex of calf on milk production (Gleddie and Berg 1968;Rutledge etal.l91l;Neville etal.1974;Robison et al 1978;Butson and Berg 1984b) For personal use only. Gleddie and Berg (1968), Butson et al (1980) and Mondragon et al (1983 …”

“…Rutledge etal. (1971), Robison et al (1978), and Butson and Berg (1984b) all reported a positive relationship between calf birth weight and milk yield.…”

“…Lawson (1981) reported that percentage of SNF increased by periods. When constituent yields are evaluated by absolute values (g d-') Butson and Berg (1984b) reported a decline over periods.…”

Milk production of crossbred daughters of high- and low-milk EPD Angus and Hereford bulls.

“…also found differences in milk production among breeds (P < .01), with daily milk for the Hereford being lowest (4.8 kg) and Simmental highest (8.0 kg). Different crosses have been found to produce different amounts of milk at peak lactation Hardt et ai., 1988), to produce different amounts of average daily milk (Daley et aI., 1987;Gaskins and Anderson, 1980;Totusek et aI., 1971;Jeffery et aI., 1971 b;Hardt et aI., 1988;Cobb et aI., 1978b;McGinty and Frerichs, 1971;Todd et aI., 1968;, and to produce different amounts of total milk Butson and Berg, 1984b). There were also breed differences in persistency (Butson and Berg, 1984a).…”

“…The effect of birth weight of the calf on milk production of the dam ranged from nonsignificant (Christian et aI., 1965; to moderately positive (Martin and Franke, 1982;Rutledge et aI., 1970a;Robison et aI., 1978;Butson and Berg, 1984b). Larger calves tended to cause their dams to produce more milk because they could consume more (Marston et aI., 1992;Drewry et aI., 1959).…”