Relationships of milk yield and quality from six breed groups of beef cows to preweaning average daily gain of their calves.

Milk yield and quality influence calf preweaning growth and ultimately the sale value of the calf at weaning. This study was conducted to evaluate the relationships of milk production and quality of beef cows to calf preweaning ADG in beef cows sired by Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano and from Brangus dams to determine whether the relationships were homogeneous across cow breed group. Approximately 50 cows/yr were milked monthly for 6 mo in each of the 7 yr of this study. Milk traits were included in models as linear and quadratic covariates along with interactions of the covariates with sire breed. Tests for curvilinearity and homogeneity of regression coefficients indicated the relationship of calf preweaning ADG to milk yield and quality was quadratic and homogeneous across Charolais and Gelbvieh; linear and homogeneous across Bonsmara, Brangus, and Romosinuano; and linear and different from other sire breeds in Herefords (P < 0.05). Exceptions to this were in the regression of calf preweaning ADG on the natural logarithm of somatic cell count (SCC) and milk urea nitrogen (MUN). The relationship of calf preweaning ADG to SCC was quadratic in Brangus (P < 0.05) and linear in Gelbvieh (P < 0.05) with little evidence (P > 0.05) of a relationship in Bonsmara, Charolais, Hereford, or Romosinuano. There was little evidence (P > 0.05) of a relationship of calf preweaning ADG to MUN in any of the sire breed groups. Results from this study confirmed the importance of the influence of milk yield and quality on calf preweaning growth but indicated this influence can depend on the breed composition of the cow. Furthermore, results suggest that breed origin or adaptation may have influenced the relationships of calf preweaning ADG to cow milk yield and quality.

Milk production traits of beef cows as affected by horn fly count and sire breed type.

Horn fly infestations negatively impact economic traits of beef cattle. Our objective was to determine the impact of horn flies on beef cattle milk yield and quality. Cows (n = 53) were derived from Brangus dams and sired by Bonsmara (n = 7), Brangus (n = 13), Charolais (n = 8), Gelbvieh (n = 5), Hereford (n = 12), and Romosinuano (n = 8) bulls. Horn fly counts and estimates of milk yield and quality were recorded monthly from May through October on individual cows. Data for milk yield and quality and horn fly count were analyzed by mixed model least squares using a linear model including sire breed, cow in sire breed, month, and month × sire breed. Effects of horn fly count on milk yield and quality were estimated by analysis of covariance using log horn fly count and log horn fly count × sire breed. Horn fly counts varied by month (P < 0.0001), with lowest population recorded in May (99 flies) and peaked in August (520 flies). Bonsmara and Gelbvieh sired cows had greater (P < 0.05) milk yield compared to Hereford sired cows (8.75 and 8.62 vs. 6.02 kg/d, respectively). Milk yield from Charolais, Romosinuano, and Brangus sired cows was intermediate (7.28, 7.00, and 7.06 kg/d, respectively). Regression of milk yield on fly count differed (P < 0.05) among sire breeds. Milk yield was reduced (P < 0.05) by 0.99 and 0.64 kg/d per unit increase in log horn fly count in Gelbvieh and Bonsmara sired cows. Regression coefficient for milk yield on log horn fly count was reduced (P < 0.01) in Gelbvieh sired cows when compared with Brangus, Charolais, Hereford, and Romosinuano sired cows, and coefficients for Bonsmara sired cows were reduced (P < 0.05) in comparison to Brangus sired cows. Increases in log fly count were associated with decreases (P < 0.05) in milk fat, solids-not-fat, and milk urea nitrogen. Milk yield was reduced (P < 0.05) by increased fly numbers depending on month of lactation and interaction with log horn fly count. In May, June, and July milk yield was reduced 0.72, 0.68, and 0.71 kg/d per unit increase in log horn fly count. Our results indicate that horn fly infestations reduce milk yield and quality of spring-calving beef cows depending on sire breed and month of lactation. Development of sustainable beef production systems may include selecting breed types whose milk yield and quality is less influenced by horn flies, allowing for better expression of genetic potential for milk yield in nutritionally challenging environments.

The clinical utility of liposomal doxorubicin in recurrent ovarian cancer.

OBJECTIVES: The aim of this study was to determine the efficacy and toxicity of single agent off-protocol, liposomal doxorubicin (Doxil Alza), in consecutive patients with recurrent ovarian cancer and to investigate the influence of HER-2/neu expression on response to liposomal doxorubicin. PATIENTS AND METHODS: Retrospective analysis of 72 consecutive patients treated, typically with liposomal doxorubicin 40 mg/m(2) q28 days between January 1997 and December 1998. Results. Twenty-nine patients (40%) had platinum- and taxane-resistant tumors. Nineteen patients (27%) responded with clinical or radiological evidence of response with reduction in CA-125 of >50%. One complete response (CR) and 7 partial responses (PRs) occurred in platinum- and taxane-resistant patients (radiological response (RR) 29%) and 8 PRs occurred in patients with visceral metastases (RR 28%). Time to progression was 5.3 (2.1-12.1) months. Only 7 dose delays (3%) and 20 dose reductions (8%) were necessary in 265 cycles of treatment. Hematological toxicity was generally mild with grade (Gr) > or =III neutropenia in 1 (2%), Gr > or =III thrombocytopenia in 1 (1%), and Gr > or =III anemia in 8 patients (11%). One patient (1%) was admitted with fever and neutropenia. Other toxicity was minimal with Gr > or =III mucositis occurring in 3 patients (4%). Gr > or =III cutaneous toxicity was seen in 6 patients (8%). Three patients (4%) had a >10% fall in ejection fraction but there was no unequivocal clinical heart failure. CONCLUSIONS: The data suggest that liposomal doxorubicin is an active drug in both taxane- and platinum-sensitive and resistant recurrent ovarian cancer. Liposomal doxorubicin is associated with tolerable toxicity and is particularly well tolerated in patients with multiple prior lines of treatment.