Effect of Lasalocid on Performance of Lactating Dairy Cows W. P. WEISS2 and B. A. AMIET Department of Dairy Science Ohio Agricultural Research and Development Center The Ohio State University Wooster 44691 ABSTRACT
(Key words: lasalocid, ionophores, feed additives)
Thirty-two midlactation dairy cows were fed either a typical dairy diet or the same diet plus 340 mg lasalocid/d for 98 d. Diets were 65% forage (alfalfa and com silage) and 35% concentrate (OM basis). Lasalocid did not affect production of milk (21 kg/d) or FCM (20 kg/d) or milk composition. Dry matter intake was slightly lower for cows consuming lasalocid than for control cows (19.6 vs. 20.6 kg/d). Lasalocid improved energetic efficiency by about 20% during the first 2 wk of the experiment, but treatment effects diminished as the experiment progressed. The period in which lasalocid had significant effects on energetic efficiency was also the period in which lasalocid increased ruminal propionate and decreased ruminal acetate concentrations. On d 7 of the experiment, cows fed lasalocid had lower acetate to propionate ratios as compared with control (3.0: 1 vs. 3.7:1). No effect of treatment was observed on ruminal VFA during the remainder of the experiment. These data are interpreted to show that lasalocid improved the efficiency of converting dietary digestible energy into NE( by altering ruminal fermentation, but this effect was relatively short-lived, since treatment effects on ruminal VFA patterns and energetic efficiency became negligible by 28 d.
INTRODUCTION
Received May 4, 1989. Accepted July 17, 1989. t Salaries and research support provided by state and federal fwlds appropriated to The Ohio State University, Ohio Agricultural Research and Development Center, and in part by Hoffmann-LaRoche, Nutley, NJ. Manuscript Number
108-89. 2Author to whom correspondence should be addressed. 1990 J Dairy Sci 73:153-162
The efficient conversion of feed energy into animal products (milk and body tissue) is important to maintain profitability of livestock enterprises. lonophores such as lasalocid and monensin increase the efficiency of converting feed into body tissue by growing beef animals (8). Ionophores are not approved currently by FDA for feeding to lactating dairy cows, so few data are available on the effects of ionophores on dairy cows performance. Dye et al. (6) conducted a short experiment (21 d) examining the influence of four concentrations of lasalocid (approximately 0, 100, 200, and 300 mg/d) on performance of early lactation cows. In general, lasalocid had very little effect on performance. Johnson et al. (10) fed early lactation cows approximately 550 mg lasalocid/d. At that dose, milk fat percentage, FCM, and OM intake were reduced significantly. Cows in mid to late lactation, in contrast to early lactation cows, generally are in positive energy balance. Diets fed to cows in mid to late lactation are also usually higher in forage than are diets fed to early lactation cows. High forage diets promote high acetate ruminal fermentations (2) whereas ionophores generally increase propionate (15). It has been suggested that propionate is used more efficiently for BW gain than is acetate (4). Therefore, cows in mid to late lactation may respond positively to ionophores. The objective of this experiment was to determine if lasalocid consumed at amounts typical for growing beef animals would affect performance and efficiency of mid to late lactation dairy cows. MATERIALS AND METHODS
Thirty-two Holstein cows averaging 170 d in lactation were divided randomly into two treat-
153
154
WEISS AND AMIET
TABLE I. Ingredient composition of concentrate mixes fed during the experiment Ingredient
Lasalocid
Control
- - (% of OM) - -
Ground ear com Soybean meal Rolled ous Debydrated alfalfa pellets Brewers dried grain Linseed meal Molasses Limestone Dicalcium phosphate Trace-mineralized salt Mineral premix 1 Urea Yitamin premix 2 Lasalocid premix 3
48.0
47.9
22.0
22.0
12.2
12.2
4.0
4.0
4.0 4.0 2.0 1.5
4.0 4.0 2.0 1.5
.7 .6 .6
.7 .6 .6
.2.2
.2
.2 .1
0
1Mineral premix composed of 50% potassium sulfale. 30% selenium premix (590 mg Sclkg). 10% copper sulfale. and 10% zinc chloride. 2Yitamin premix provided 1..500.000 IV vitamin A; 150.000 IV vitamin 0; and 4500 IV vitamin Elkg premix.
3Lasa1ocid premix provided 51 g lasalocidlkg premix.
ment grOUps. Treatments were control or conttol diet plus 340 mg lasalocid/d (Tables 1 and 2). Cows were introduced abruptly to the diets and remained on the treattnents for 14 wk.. The experiment was conducted in two blocks over time with 8 cows per treatment per block. Diets were identical for each block except for normal variations in forage composition. Preliminary milk production, BW. and feed intake were similar between treatments and blocks. Two
first lactation cows per treatment were used during block I, but all cows used in block 2 were in at least their second lactation. Cows were individually fed the mixed diets once daily for ad libitum consumption. Milk and feed weights were recorded daily. Cows were weighed once every 2 wk throughout the experiment. Average daily change in BW (AOO) for the entire experiment (within each block) was determined by regressing BW of each cow over time. The slope of the regression line was used to estimate AOO. The ADO for each time period (2 to 3 wk) was determined by subtracting the initial BW for the period from the final BW for the period and dividing by days. That value was used to calculate energetic efficiency over time. Milk was sampled (a.m. and p.m.) on d 0, 7, 14, and every 2 wk thereafter for milk fat and protein analysis using infrared spectrophotometry. All feeds were sampled biweekly and composited by month. Feeds were analyzed for DM (l00·C oven), CP (1), NDF, ADF (14), estimated NEI (5), and Ca, P, Mg, and K using plasma emission spectroscopy. Samples of each batch mix of concentrates were taken and analyzed for lasalocid using fluorometry (conducted by HoffrnannLaRoche, Nutley, NJ). Orts were sampled monthly and analyzed for DM and ADF. Concentration of ADF in orts was used to determine whether cows were preferentially consuming concentrate or forage. Acid detergent fiber concenttation in orts averaged 33% and was essentially the same for all cows indicating no preferential consumption patterns. Four cows per treatment per block were randomly chosen at the start of each block for
TABLE 2. Ingredient and nutrient composition of diets (OM basis) fed to cows during tbe experiment. Lasalocid
Control
Ingredient Alfalfa bay. % Alfalfa silage. % Com silage, % Concentrate, % CP. % NDF, % NE!. McaJ..1tg Ca, % P. % Lasalocid. ppm JournaJ of Dairy Science Yol. 73.
Block 1
Block 2
Block 1
Block 2
10.0 25.0 30.0 35.0
10.0 25.0 30.0 35.0
10.0 25.0 30.0 35.0
10.0 25.0 30.0 35.0
17.7 37.5 1.59
19.5 34.0 1.62 .92 .36
18.0 36.5 1.60 .97 .37 17.1
19.0 33.6 1.62 .92 .39 17.3
.86 .36
No. I, 1990
155
LASALOCID FOR LACfATING COWS
rumen fluid sampling, and cows were stomach tubed approximately 3 h postfeeding on d 0, 7, 28, and 98 of the trial. Samples were acidified with 25% metaphosphoric acid and analyzed for VFA using gas chromatography (17). Energetic efficiencies were calculated by first estimating digestible energy (DE) content of the diet (5). The NEI requirements for maintenance, FCM production, and changes in body mass were calculated (13). Th~ NRC uses different energies for weight gains and losses, but due to the inaccuracies present in measuring ADO in this experiment (see below), the energy value was rounded to 5 Mcal/kg BW change. Finally, total energy requirement was divided by DE intake to give energy efficiency. Performance data (milk production and composition, DM intake, and change in BW) were analyzed using two models. First the data within each block were analyzed separately using model 1. Data from the two blocks were then combined and analyzed according to model 2. Week was included in the models so that interactions between treatment and time could be examined. Period (2 to 3 wk) was used instead of week as the time variable for changes in BW and energetic efficiencies since cows were not weighed weekly. Rumen data were analyzed according to the same models except that week was replaced by sample d (7, 28, and 98), and only 12 d.f were available for cow. One cow fed the lasalocid diet died during the 11th wk of the first block. Necropsy examination revealed no unusual organ structure, but severe lesions were found in the feet (herniation of the sole, foot rot, chronic bursitis, and chronic laminitis). Performance of that cow was poor during most of the experiment, so her data were discarded, resulting in an unbalanced design (n 15 cows for lasalocid and 16 for control). Least squares analysis of variance procedures were used to analyze the data (9). Model 1 (within blocks);
=
Yijk
=+
Ti + C(i)j + Wk + TWik
+ TWC(j)jk
where: Yijk = dependent variable of cow j fed the treattnent i during the week
k;
Ti
= effect
of treatment i (1 df);
Wk TWik
= =
TWC(j)jk
=
effect of cow j within treatment i (13 d.f for block 1 and 14 df for block 2); error term used to test treatment effect; effect of week k (13 df); effect of inleraction between treatment i and week k (13 df); and effect of cow j within treatment i during week k (169 df for block 1 and 182 df for block 2); error term for treatment by week interaction.
Model 2 (including block): Yjjkm
=+
Bi + Tj + C(ij)k + W m + BWim + TWjm + BTWijm
+ BTWC(ij)km where: = effect of block i (1 df); effect of cow k within block i fed the trealment j (the block by treatment interaction was included in this term (27 + 1 28 df); error term for treatment; effect of interaction between BTWijm block i treatment j and week m (13 df); and effect of interaction between BTWC(ij)km cow k during week m within treatment j and block i (351 df); error term for treatment by week interaction.
=
=
= =
Other terms are as in model 1. The effects of interest were treatment and the treatment by time interaction. Other effects and interactions were used only to decrease the size of the error terms. RESULTS
Composition of the diets is in Table 2. Due to the quality of the forages, concentration of CP in the diets (especially during block 2) was higher than anticipated. Otherwise, nutrient concentrations in the experimental diets were similar to those recommended by NRC (13). The concentration of lasalocid was chosen to Journal of Dairy Science Vol. 73,
No. I, 1990
156
WEISS AND AMlET
TABLE 3. Performance of cows (Block 1) fed diets with or without lasalocid for 14 wk. Item
Control
No. cows Milk. kg/d FCM. kgld Milk fat. % Milk fat. kgld Milk protein. % Milk protein. kgld DM Intake, kgld DM Intake, % BW BW, kg AOO.! kgld
8 21.0 20.7 3.9 .82 3.4 .71 21.0 3.31 636 .44
Lasalocid 7 20.5 19.6 3.8 .76 3.3
SE 1.1 1.2 .18
.06
18.9 3.01 628 .67
.75
.54 .57 .50
.12
.80 .60 .09 .11
.08
.09
.08 .03
.68
p
(Key words: lasalocid, ionophores, feed additives)
Thirty-two midlactation dairy cows were fed either a typical dairy diet or the same diet plus 340 mg lasalocid/d for 98 d. Diets were 65% forage (alfalfa and com silage) and 35% concentrate (OM basis). Lasalocid did not affect production of milk (21 kg/d) or FCM (20 kg/d) or milk composition. Dry matter intake was slightly lower for cows consuming lasalocid than for control cows (19.6 vs. 20.6 kg/d). Lasalocid improved energetic efficiency by about 20% during the first 2 wk of the experiment, but treatment effects diminished as the experiment progressed. The period in which lasalocid had significant effects on energetic efficiency was also the period in which lasalocid increased ruminal propionate and decreased ruminal acetate concentrations. On d 7 of the experiment, cows fed lasalocid had lower acetate to propionate ratios as compared with control (3.0: 1 vs. 3.7:1). No effect of treatment was observed on ruminal VFA during the remainder of the experiment. These data are interpreted to show that lasalocid improved the efficiency of converting dietary digestible energy into NE( by altering ruminal fermentation, but this effect was relatively short-lived, since treatment effects on ruminal VFA patterns and energetic efficiency became negligible by 28 d.
INTRODUCTION
Received May 4, 1989. Accepted July 17, 1989. t Salaries and research support provided by state and federal fwlds appropriated to The Ohio State University, Ohio Agricultural Research and Development Center, and in part by Hoffmann-LaRoche, Nutley, NJ. Manuscript Number
108-89. 2Author to whom correspondence should be addressed. 1990 J Dairy Sci 73:153-162
The efficient conversion of feed energy into animal products (milk and body tissue) is important to maintain profitability of livestock enterprises. lonophores such as lasalocid and monensin increase the efficiency of converting feed into body tissue by growing beef animals (8). Ionophores are not approved currently by FDA for feeding to lactating dairy cows, so few data are available on the effects of ionophores on dairy cows performance. Dye et al. (6) conducted a short experiment (21 d) examining the influence of four concentrations of lasalocid (approximately 0, 100, 200, and 300 mg/d) on performance of early lactation cows. In general, lasalocid had very little effect on performance. Johnson et al. (10) fed early lactation cows approximately 550 mg lasalocid/d. At that dose, milk fat percentage, FCM, and OM intake were reduced significantly. Cows in mid to late lactation, in contrast to early lactation cows, generally are in positive energy balance. Diets fed to cows in mid to late lactation are also usually higher in forage than are diets fed to early lactation cows. High forage diets promote high acetate ruminal fermentations (2) whereas ionophores generally increase propionate (15). It has been suggested that propionate is used more efficiently for BW gain than is acetate (4). Therefore, cows in mid to late lactation may respond positively to ionophores. The objective of this experiment was to determine if lasalocid consumed at amounts typical for growing beef animals would affect performance and efficiency of mid to late lactation dairy cows. MATERIALS AND METHODS
Thirty-two Holstein cows averaging 170 d in lactation were divided randomly into two treat-
153
154
WEISS AND AMIET
TABLE I. Ingredient composition of concentrate mixes fed during the experiment Ingredient
Lasalocid
Control
- - (% of OM) - -
Ground ear com Soybean meal Rolled ous Debydrated alfalfa pellets Brewers dried grain Linseed meal Molasses Limestone Dicalcium phosphate Trace-mineralized salt Mineral premix 1 Urea Yitamin premix 2 Lasalocid premix 3
48.0
47.9
22.0
22.0
12.2
12.2
4.0
4.0
4.0 4.0 2.0 1.5
4.0 4.0 2.0 1.5
.7 .6 .6
.7 .6 .6
.2.2
.2
.2 .1
0
1Mineral premix composed of 50% potassium sulfale. 30% selenium premix (590 mg Sclkg). 10% copper sulfale. and 10% zinc chloride. 2Yitamin premix provided 1..500.000 IV vitamin A; 150.000 IV vitamin 0; and 4500 IV vitamin Elkg premix.
3Lasa1ocid premix provided 51 g lasalocidlkg premix.
ment grOUps. Treatments were control or conttol diet plus 340 mg lasalocid/d (Tables 1 and 2). Cows were introduced abruptly to the diets and remained on the treattnents for 14 wk.. The experiment was conducted in two blocks over time with 8 cows per treatment per block. Diets were identical for each block except for normal variations in forage composition. Preliminary milk production, BW. and feed intake were similar between treatments and blocks. Two
first lactation cows per treatment were used during block I, but all cows used in block 2 were in at least their second lactation. Cows were individually fed the mixed diets once daily for ad libitum consumption. Milk and feed weights were recorded daily. Cows were weighed once every 2 wk throughout the experiment. Average daily change in BW (AOO) for the entire experiment (within each block) was determined by regressing BW of each cow over time. The slope of the regression line was used to estimate AOO. The ADO for each time period (2 to 3 wk) was determined by subtracting the initial BW for the period from the final BW for the period and dividing by days. That value was used to calculate energetic efficiency over time. Milk was sampled (a.m. and p.m.) on d 0, 7, 14, and every 2 wk thereafter for milk fat and protein analysis using infrared spectrophotometry. All feeds were sampled biweekly and composited by month. Feeds were analyzed for DM (l00·C oven), CP (1), NDF, ADF (14), estimated NEI (5), and Ca, P, Mg, and K using plasma emission spectroscopy. Samples of each batch mix of concentrates were taken and analyzed for lasalocid using fluorometry (conducted by HoffrnannLaRoche, Nutley, NJ). Orts were sampled monthly and analyzed for DM and ADF. Concentration of ADF in orts was used to determine whether cows were preferentially consuming concentrate or forage. Acid detergent fiber concenttation in orts averaged 33% and was essentially the same for all cows indicating no preferential consumption patterns. Four cows per treatment per block were randomly chosen at the start of each block for
TABLE 2. Ingredient and nutrient composition of diets (OM basis) fed to cows during tbe experiment. Lasalocid
Control
Ingredient Alfalfa bay. % Alfalfa silage. % Com silage, % Concentrate, % CP. % NDF, % NE!. McaJ..1tg Ca, % P. % Lasalocid. ppm JournaJ of Dairy Science Yol. 73.
Block 1
Block 2
Block 1
Block 2
10.0 25.0 30.0 35.0
10.0 25.0 30.0 35.0
10.0 25.0 30.0 35.0
10.0 25.0 30.0 35.0
17.7 37.5 1.59
19.5 34.0 1.62 .92 .36
18.0 36.5 1.60 .97 .37 17.1
19.0 33.6 1.62 .92 .39 17.3
.86 .36
No. I, 1990
155
LASALOCID FOR LACfATING COWS
rumen fluid sampling, and cows were stomach tubed approximately 3 h postfeeding on d 0, 7, 28, and 98 of the trial. Samples were acidified with 25% metaphosphoric acid and analyzed for VFA using gas chromatography (17). Energetic efficiencies were calculated by first estimating digestible energy (DE) content of the diet (5). The NEI requirements for maintenance, FCM production, and changes in body mass were calculated (13). Th~ NRC uses different energies for weight gains and losses, but due to the inaccuracies present in measuring ADO in this experiment (see below), the energy value was rounded to 5 Mcal/kg BW change. Finally, total energy requirement was divided by DE intake to give energy efficiency. Performance data (milk production and composition, DM intake, and change in BW) were analyzed using two models. First the data within each block were analyzed separately using model 1. Data from the two blocks were then combined and analyzed according to model 2. Week was included in the models so that interactions between treatment and time could be examined. Period (2 to 3 wk) was used instead of week as the time variable for changes in BW and energetic efficiencies since cows were not weighed weekly. Rumen data were analyzed according to the same models except that week was replaced by sample d (7, 28, and 98), and only 12 d.f were available for cow. One cow fed the lasalocid diet died during the 11th wk of the first block. Necropsy examination revealed no unusual organ structure, but severe lesions were found in the feet (herniation of the sole, foot rot, chronic bursitis, and chronic laminitis). Performance of that cow was poor during most of the experiment, so her data were discarded, resulting in an unbalanced design (n 15 cows for lasalocid and 16 for control). Least squares analysis of variance procedures were used to analyze the data (9). Model 1 (within blocks);
=
Yijk
=+
Ti + C(i)j + Wk + TWik
+ TWC(j)jk
where: Yijk = dependent variable of cow j fed the treattnent i during the week
k;
Ti
= effect
of treatment i (1 df);
Wk TWik
= =
TWC(j)jk
=
effect of cow j within treatment i (13 d.f for block 1 and 14 df for block 2); error term used to test treatment effect; effect of week k (13 df); effect of inleraction between treatment i and week k (13 df); and effect of cow j within treatment i during week k (169 df for block 1 and 182 df for block 2); error term for treatment by week interaction.
Model 2 (including block): Yjjkm
=+
Bi + Tj + C(ij)k + W m + BWim + TWjm + BTWijm
+ BTWC(ij)km where: = effect of block i (1 df); effect of cow k within block i fed the trealment j (the block by treatment interaction was included in this term (27 + 1 28 df); error term for treatment; effect of interaction between BTWijm block i treatment j and week m (13 df); and effect of interaction between BTWC(ij)km cow k during week m within treatment j and block i (351 df); error term for treatment by week interaction.
=
=
= =
Other terms are as in model 1. The effects of interest were treatment and the treatment by time interaction. Other effects and interactions were used only to decrease the size of the error terms. RESULTS
Composition of the diets is in Table 2. Due to the quality of the forages, concentration of CP in the diets (especially during block 2) was higher than anticipated. Otherwise, nutrient concentrations in the experimental diets were similar to those recommended by NRC (13). The concentration of lasalocid was chosen to Journal of Dairy Science Vol. 73,
No. I, 1990
156
WEISS AND AMlET
TABLE 3. Performance of cows (Block 1) fed diets with or without lasalocid for 14 wk. Item
Control
No. cows Milk. kg/d FCM. kgld Milk fat. % Milk fat. kgld Milk protein. % Milk protein. kgld DM Intake, kgld DM Intake, % BW BW, kg AOO.! kgld
8 21.0 20.7 3.9 .82 3.4 .71 21.0 3.31 636 .44
Lasalocid 7 20.5 19.6 3.8 .76 3.3
SE 1.1 1.2 .18
.06
18.9 3.01 628 .67
.75
.54 .57 .50
.12
.80 .60 .09 .11
.08
.09
.08 .03
.68
p
