Supplemental fat for dairy calves during mild cold stress.

Eighty-one Holstein and Holstein-cross dairy calves fed calf milk replacer (CMR) were used to determine response to increasing amounts of supplemental fat during mild cold stress. Calves (n=27) were randomly assigned to 1 of 3 treatments: (1) low fat [LF; 28% crude protein:15% fat milk replacer (28:15 MR)]; (2) medium fat [MF; 28:15 MR+113 g/d of commercial fat supplement (FS)]; (3) high fat (HF; 28:15 MR+227 g/d of FS). The MF and HF calves received FS from d 2 to 21, and all calves were fed LF from d 22 to 49. The CMR was fed at 1.4% of birth body weight (BBW) from d 1 to 10, at 1.8% of BBW from d 11 to 42, and at 0.9% of BBW from d 43 to 49. Calves were weaned on d 49 and remained in hutches until d 56. The CMR was reconstituted to 13% solids. Calves were fed a commercial starter grain (19.2% crude protein on a dry matter basis) ad libitum and offered warm water after CMR feeding. Calves were fed CMR twice daily at 0630 and 1730 h in hutches bedded with straw. Starter intake, CMR intake, and ambient temperature were measured daily, and body weight (BW), hip height, and body length were measured weekly. Data were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC) as a randomized design with linear and quadratic contrasts. Calf BBW averaged 42.0 ± 1.0 kg, total serum protein averaged 5.8 ± 0.1mg/dL, and birth ambient temperature averaged 5.0 ± 1.1°C. Feeding FS increased metabolizable energy intake (MEI) over maintenance but decreased efficiency of conversion of BW gain:MEI. Starter intake by LF calves was greatest until the beginning of weaning, after which starter intake was similar among treatments. Because of higher starter intake, total MEI was similar among treatments. Feed efficiency through d 49 was greater for calves fed MF and HF. Average daily gain during fat supplementation was greater for MF and HF than for LF. Lack of increase in BW gain and feed efficiency between MF and HF treatments indicated that HF did not result in advantages over MF. Supplementing fat to preweaned calves fed CMR increased BW gain and decreased starter intake through d 21 which had carryover effects on starter intake on d 49 and reduced hip height and tended to reduced withers height and body length by d 56. The addition of supplemental fat to LF, during mild cold stress, may result in a suboptimal ratio of crude protein to metabolizable energy in the CMR.

Effects of prepartum controlled-energy wheat straw and grass hay diets supplemented with starch or sugar on periparturient dairy cow performance and lipid metabolism.

This study examined the effects of a forage source [wheat straw (WS) versus grass hay (GH)] prepartum and supplemental carbohydrate source [corn (dry feed; DF) versus molasses (liquid feed; LF)] on pre- and postpartum intake, digestibility, selective particle consumption, milk yield, and lipid metabolism. The objectives were to determine if forage or pre- and postpartum supplement alters periparturient intake, energy balance, and milk yield. Sixty (n=15) multiparous dairy cows were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments to compare WS versus GH diets supplemented with either DF or LF. Dietary treatments were (1) WS prepartum + DF pre- and postpartum (WSDF), 2) WS prepartum + LF pre- and postpartum (WSLF), (3) GH prepartum + DF pre- and postpartum (GHDF), and (4) GH prepartum + LF pre- and postpartum (GHLF). Treatments began at dry-off, × before expected calving. During the prepartum phase, cows maintained dry matter intake (DMI) at 2.0% of body weight and prepartum energy balance remained positive for all treatments until calving. Prepartum GH diets had a more positive energy balance compared with WS diets. On week -5, energy balance was more positive for GHDF than for WSDF or GHLF. Energy balance for WSLF, however, was lower on week -3 and -1 than GHDF. Liquid feed decreased dry matter digestibility and increased prepartum liver triglyceride, serum nonesterified fatty acids (NEFA), and tended to increase ß-hydroxybutyrate. After calving, LF decreased DMI and energy balance, but not yield of milk or 3.5% fat-corrected milk, resulting in greater feed efficiency compared with DF. Forage did not affect postpartum DMI, but milk yield tended to be higher for WS versus GH. The DMI expressed as percentage of body weight was not affected by supplement or prepartum forage type. Cows fed WS had lower serum NEFA, higher liver glycogen, and tended to have a lower triglyceride to glycogen ratio postpartum than GH. Serum NEFA peaked on d 14 for all treatments and then declined thereafter. In postpartum diets, more particles were retained on the top screen for LF (>19.0mm) of the Penn State Particle Separator, which also tended to have more particles in the second screen (particles 19.0-8.0mm). Supplement had minimal effect on postpartum selective particle consumption. In conclusion, feeding diets containing WS resulted in lower postpartum serum NEFA, higher liver glycogen, and a tendency for greater milk production and lower liver triglyceride to glycogen than those containing GH. Liquid feed reduced postpartum DMI but not yield of milk yield or 3.5% fat-corrected milk yield, resulting in an improvement in feed efficiency. Future research should continue to investigate the use of single dry cow diet feeding strategies as they affect pre- and postpartum animal responses.

Effects of milk replacer program fed 2 or 4 times daily on nutrient intake and calf growth.

The aims of this study were to determine if feeding frequency (FF) of milk replacer (MR; meals/d) alters starter intake, growth, and efficiency of growth in nursery calves fed a conventional or accelerated MR. We hypothesized that smaller and more frequent MR meals would increase starter intake and growth when greater amounts of MR nutrients are fed to nursery calves. Forty-eight Holstein and Holstein-cross heifer and bull calves were assigned to treatments in a 2 × 2 factorial arrangement of MR and FF. Treatments included (1) standard 20% CP and 20% fat MR fed at 1.5% of body weight (BW; 2 meals/d; STD2), (2) standard 20% CP and 20% fat MR fed at 1.5% of BW (4 meals/d; STD4), (3) modified 26% CP and 18% fat MR fed at 2.0% of BW (2 meals/d; MOD2), and (4) modified 26% CP and 18% fat MR fed at 2.0% of BW (4 meals/d; MOD4; n=12). All calves were fed at 0600 and 1700 h and STD4 and MOD4 calves were fed 2 additional meals at 1100 and 1400 h, resulting in the same amount of MR offered for the 2 × and 4 × treatments. Treatments were fed from d 2 to 42 of age and all MR feeding rates were adjusted weekly to maintain MR solids intakes at 1.5 or 2.0% of BW for STD and MOD diets, respectively, and were reconstituted to 15% total solids. Milk replacer FF was reduced by 50% on d 36 and calves were weaned on d 42. Calves were housed in hutches bedded with straw and offered water and a texturized 18% CP starter ad libitum. Calf body weight and body structure were measured weekly and starter intake and fecal scores were measured daily. Through both 42 and 56 d, calves fed MOD had greater CP and fat intake, resulting in increased average daily gain, heart girth, circulating nonesterified fatty acids (NEFA), and muscle total lipid compared with calves fed STD diets. Calves fed MOD diets consumed less starter grain than STD calves but total dry matter intake was similar among treatments. Increased FF for STD calves resulted in greater starter intake at weaning but increasing FF of MOD calves did not have this effect. Due to differences in starter intake, total dry matter by calves through d 56 was similar across treatments. Additionally, increased FF tended to increase serum NEFA concentrations. Serum NEFA concentration was negatively correlated with starter intake. The BW of calves fed STD2 and STD4 treatments almost doubled and the BW of calves on the MOD2 and MOD4 treatments doubled by d 56. Increased FF of the conventional MR program but not accelerated MR program increased starter intake. Increased FF did not affect growth, starter intake, or gain:feed ratio.