Objective: This meta-analysis was done with the aim of cultivating farmers decision in feeding their dairy cows for substituting several silage types, hay and maturity-based comparison feeds to improve dairy cows’ performance.

Methods: The data that have booked in data sheet from previous published researches was based on the measurement of inclusion criteria with its relevancy for the research objective. A database includes 71 papers that were published among the interval of 1984-2020 years. In the current meta-analysis, the comparison treatments were differing in feed types but similar for all other parameters.

Result: On the current meta-analysis there were six sub-grouped various silage and hay comparison feed types. The comparison of alfalfa hay maturity shows no significantly difference in all cows measuring parameters of DMI, milk yield and milk composition. The reason probably due to small data set used for analysis. Similarly, for the comparisons' alfalfa silage with corn silage and silage with hay didn’t show any significance difference. On the other hand, the comparisons of early cut silage with late cut silage, sorghum with corn silage, and grass silage with legume silage; early cut silage, corn silage and legume silage were significantly higher from their comparison diet at least in milk yield. However, for feed efficiency from all over the comparisons, the effect of silage maturity was only significantly differed over late cut silage.

Conclusion: based on the results shown on the collective meta experimental data, in the comparison of early cut silage with late cut silage; early cut silage gives higher MY and converts feed more efficiently to production than late cut silage but for others paired comparisons feed efficiency was not significantly differed. Therefore, except silage maturity, most comparison feed types were recommended to be replaceable with further studying forages cost-effectiveness and their accessibility.

Keywords: lactating cows, forage, performance, feed efficiency

ADF, Acid Detergent Fiber; ADL, Acid Detergent Lignin; AI, Artificial Insemination; AS- Alfalfa Silage; CI, Calving Interval; CON, Control; CP, Crude Protein either Feed or Milk; CS, Corn Silage; DMI, dry matter intake; DMY, Daily Milk Yield; FCA, First Calving Age; GS, Grass Silage; Kg, Kilogram; Kg/d, Kilogram per day; L, liter; LS, Legume Silage; MY, Milk Yield; NDF, Neutral Detergent Fiber; TRT, Treatment; SPSS, Statistical Package for Social Science; SS, Sorghum Silage; TMY, Total Milk Yield; Vs, versus

Feed and feeding are prerequisite necessities in dairy farming. For their nutrition, as dairy cattle are social animals that operate in herd structure the owner needed to energetically deliberate, understand and realize their comfort in following dairy cattle responses to various types of feeds by watching how their productivity have gone.¹ In preparation of diet, amount of moisture-corrected nutrient primary estimated to feed lactating cows is a dry matter intake. In fact, the compulsory of dry matter intake is most importantly to prevent either under feeding or overfeeding; to meet the nutrient needs of dairy cows appropriately for increasing productivity and to decrease healthy problem of productive cows. In dairy farm feeding appropriate nutrient for need of lactating cows is obligatory as under feeding restrict production and damage cow’s health. Whereas, overfeeding wastes feed and also affects the environment through excessive excretion of nutrients. Based on these reasons’ preparation of dray matter intake is very crucial to be economical by increasing the productivity of dairy cows with appropriate feeding.² The way forward to solve feed intake variation between lactating cows is grouping cows based on their nutrient requirement.² The amount of feed intake in comparison between individual and group; individually fed cows eat less hay than group this was probably because of augmented nerviness of cows.¹ Similarly, grouping cows eat more feed than separate feeding because competition for feed whether a cow is hungry or not, group feeding stimulates others to eat.³

In dairy farming body condition score of cows’ background is a factor for milk composition; in which thin group cows displayed Strictly lower fat and makes total solids lower.⁴ On the other hand, the content of forage cell wall determines cow’s voluntary intake, feeds with high cell-wall content had lower voluntary intake than low cell-wall content and also quantity of digestible energy inclined voluntary intake.⁵ A cattle wants a manager to not eat in a smooth surface in natural grazing position.² The advantage of eat with head down is to eliminate feed waste related with elevated bunks in feed tossing and saliva formation of cows eat with their head down produces 17% more saliva than that of cows eat in horizontal position.¹ Furthermore, temperature affect feed intake and production of lactating cows; these decreases on the increment of ambient temperature in which the thermal neutral zone of dairy cattle is between 5 to 20 ⁰c. The dairy cattle water consumption increases up to temperature reading of 35 °C, but because of idleness of feed intake when temperature increase further water consumption declines. Correspondingly, coldness affect feed intake in which cows to resist the cold stress they increases feed intake, thermal insulation and basal metabolic intensity, reticulo-rumen motility and passage rate but, the extremeness of cold didn’t increase feed intake rather cows become negative energy balance.²

Research question: For people of Africa feed self-sufficiency and poverty alleviation dairy production is one of the vital rural development sector; still the potential remains underexploited.⁶ African dairy stacked by many difficulties such as; breed, feed resources and low adoption of improved technologies; most importantly feed availability was a great influence for the sector.^7,8 Feed shortage was extremely critical⁹ due to this reason most farmers fed lactating cows only maintenance needs.¹⁰ The knowledge gap of farmers to formulate feed technologies makes feed costly to get and this gap enforces farmers to feed cows low quality feeds like unimproved straw and hay.^11,12 In dairy farm for the success of farm owner farmer’s milk and feed price are the basics that has placed primarily for the decision of tomorrow environment. If price is well to continue their farm farmers hopefully facilitate their activity rather, no question to stop their farm completely.¹³ The terrible of insufficient quality and quantity of feeds was most importantly due to over grazing, Shortage of land, variability of weather and population augmentation.^13-15 The absence of more feed processing companies makes dairy sector more complex especially in dry season feed depreciates in quality and rises in cost. This serious shortage ended up to closing the farm by decreasing milk yield, increasing mortality rate of young calf, lengthen parturition interval and retarded growth rate.^10,14

The purposes of meta-analysis: In making more measurable discussion, experience and share more accurate and advanced knowledge for synthesizing strong phenomenon in a specified research problem with multi-quantitative data meta-analysis has chosen to do so. Based on farmers collective consequences that have stated before in the research question the meta-research has tried to show feed options as a solution for available feed constraints with collective effort of meta-data. Moreover, this meta-analysis has taken as an encouragement for farmers in attempting to deduce the consequence of switching those comparison feeds in a dairy production. 

The aim of meta-analysis was to evaluate effects of substituting various feeds for familiarizing farmers productivity-based decision on cows fed either silage or hay; legume or grass silage; early or late harvest; corn or sorghum silage; corn or alfalfa silage as a daily diet. The main objective of this meta-analysis was to compare and examine effect of maturity, silage and hay of various feeds on feed intake and milk productivity of lactating cows. The hypothesis was replacement of dairy cow’s diet based on maturity, hay and silage of various feeds have a significant effect on feed intake and milk productivity.

Database establishment

The data that have terminated in datasheet was searched in “google scholar” with keywords of: “lactating cows”, “milk production”, “forage maturity” and “silage” and “hay” or reference method from other collected researches. The resulting papers that have used for this meta-analysis were checked on references. The meta-analysis aims to quantify and investigate effect of harvesting time, silage and hay of various feed types on lactating cow’s DMI, milk yield and composition. On this regard 71 papers were marked and take part for analysis based on their relevancy for the comparison of present study. The meta multiple researches that have been analyzed were published for the last 1984-2020 years.

The inclusion criteria for experiments of meta-analysis were: papers that have at least one comparison feeds in the research, clearly stated DMI and milk productivity (MY and composition), similar status of lactating cows with only differ in feed types so that; breed-based comparisons, conference abstracts and quantitative survey reports were not included. The researches that have conducted with two strong significant trail experiments in one research paper and that fulfill the inclusion criteria each trail have included as one research. Generally, the researches that have used control measures of lactating cows other than feed difference were referred as an excluded paper.

This meta-analysis containing six pair set of feed comparisons. Dairy cows fed either control or treatment. The feed categories are maturity of alfalfa hay, maturity of silage, sorghum & corn silage, corn & alfalfa silage, grass & legume silage and lastly silage & hay comparisons based on cows DMI and productivity performance. Furthermore, the meta was designed for encouragement of farmers in attempting to deduce the consequence of switching off low productive feeds on lactating cows.

Statistics

In this meta-analysis the assembled data of various studies reported DMI, MY, milk fat content and protein content as comparison with different feed types. The analysis was done for the purpose of comparing two feed types for their response on lactating cows’ productivity. Almost all previous studies of each comparison were mandated to compare with full productivity parameters of lactating cows within the research criteria. Other feed or milk quality determinant traits like feed digestibility, NDF or ADF content were examined only as a systematic review without any statistical analysis. The average value of each treatment was calculated before statistical analysis. Statistical analysis was performed by using SPSS version 22. So that the researcher used the software by following appropriate procedures.  

Result

Alfalfa hay maturity

The comparison of early and late harvest AH data set ended by considering each meta-data into account. The result shows DMI, MY and composition of early and late harvest AH was not significantly differed (Table 2). The reason probably availability of data that have used for comparison was with smaller observations. Furthermore; lactating cows that fed early harvest AH efficiently converts feed to milk in 0.45kg times greater portion of its dry matter intake. On the other hand, late harvest AH efficiently converts feed to milk 0.50 kg times greater portion of its dry matter intake. Feed efficiency between diets were not significantly differed (P=0.1).

Silage maturity

The comparison of early and late cut of silage maturity shows that early cut silage was significantly higher on cow’s milk yield and feed efficiency (p=0.001, 0.02) for MY and feed efficiency respectively (Table 3). On the other hand, maturity was not significantly differed for DMI and milk composition. Feed conversion efficiency of early cut silage converts feed to production 0.4 kg/day times greater portion of its dry matter intake whereas late cut converts 0.35kg/day times greater portion of its dry matter intake.

Corn and alfalfa silage

The result of comparison CS and AS fed cows were observed with no significant difference on DMI, MY and composition (Table 4). Lactating cows that fed CS efficiently converts feed to milk in 0.48kg greater portion of its DMI and 0.50 kg greater for AS; but feed efficiency wasn’t show any significant difference between the diet (P=0.76).  Furthermore, numerically AS fed lactating cows were produce 0.27 kg more MY than corn diet and also fat content of AS fed cows gives 0.11 percentage more fat content than CS fed cows. Although there was a difference in cows’ productivity and feed efficiency between the diet but it was not significantly differed.

Sorghum and corn silage

The Comparison of CS and SS of the collected data analyzed with contribution of each data set for the result. The result shows that there was a significant difference between the diet; in which CS fed cows has taken 1.64 kg/d more DMI and produces 1.81kg/d MY than SS (P=0.04& 0.02) (Table 5).

Moreover, milk composition (fat and protein content) of the diet was not significantly differed (P=0.83, 0.61) for fat and protein content respectively. In feed efficiency cows efficiently converts 0.27kg and 0.29kg of milk greater portion of its DMI for CS and SS respectively. However, feed efficiency between the diet was not significantly differed (P=0.65). Generally, result states although comparison fed cows show significant difference on milk yield and DMI but feed efficiency and milk composition were not significantly differed.

Silage and hay

The result shows that silage and hay fed cows were not significantly differed on their DMI, milk yield and Composition. Although, milk yield of silage fed lactating cows was greater and DMI was greater for hay fed cows but it was not significantly deviated (P=0.13, 0.61) for DMI and milk yield respectively (Table 6). Particularly for milk composition fat content was greater on silage fed cows and protein was higher on hay fed cows but milk composition as general was not significantly differed. Furthermore, lactating cows that fed silage efficiently converts feed to milk in 0.55kg above its dry matter intake. Whereas in the cows feeding hay converts 0.50 kg greater above its dry matter intake feed efficiency was not significantly differed between the diet(P=0.07).

Legume and grass silage

When we compare GS and LS DMI of LS was significantly higher in taking higher diet than GS. The present result shows that LS fed cows were observed with 1.84 kg more dry matter than GS (P=0.002) (Table 7). Similarly, milk yield and milk protein content also significantly differed which was 1.82 kg higher and 0.06 percentage lesser on LS fed cows over GS (P= (0.001 & 0.03) for milk yield and protein respectively. On the other hand, milk fat content of the diet was not significantly differed (P=0.58).

Moreover; lactating cows that fed LS efficiently converts feed to milk 0.53kg times greater portion of its dry matter intake. On the other hand, the cows feeding GS converts feed to milk 0.57kg times greater portion of its dry matter intake. Generally, the result indicates even though milk yield, DMI and protein content shows significant difference between the diet but feed efficiency was not significantly differed (P=0.4).

Alfalfa hay maturity

The result shows that DMI, milk yield and milk composition of both early and late cut fed cows were not significantly differed. Similarly, the earlier findings also confirm that milk yield and milk composition of cows was not affected by maturity of AH.^16-19 Rationally the maturity of hay decreasing digestibility of dry matter in 0.4% per day²⁰ and this maturity of hay affect cows to take more time for ruminating, chewing and a greater volume of rumen contents which decreases dry matter intake^17,19 but it was not show any difference for dry matter intake for this meta result; probably the small data set used for analysis. On the other hand, matured AH contained slightly lower content of CP and greater NDF content this endorsed to a greater loss of leaves during harvest and low nutritional value^17,19 and the feeds with their protein content increasingly less would depress the ruminal microorganism synthesis of amino acid and protein; those all causes for continuously decrease rate of reticulorumen digesta and feed intake.²¹

Silage maturity

In comparing Silage maturity, the result shows that milk yield and feed efficiency were significantly higher on early cut fed cows (P=0.001 &0.02) for milk yield and feed efficiency respectively. Similarly, the previous finding confirm that late cut alfalfa silage fed cow’s milk yield were less than early cut but for milk composition it was not significantly differed.^17,18,22 On the other hand, early cut corn and sorghum silage fed cows produce greater milk yield over late cut silage.^23,24 This different probably because of the diet crude protein was excellent quality on early cut and the increment of NDF, ADF and ADL content on late cut decreases nutrient content of diet.^17-19

The result didn’t show any significant difference on dry matter intake and milk composition. In contrast previous finding of grass-barley multi-cultivated late cut silage DMI was significantly higher than early cut. But milk yield and milk protein content were not influenced by maturity; milk fat content was higher on early harvest (P<0.05).^25,26 On the other hand, for feed efficiency the result shows that early cut silage fed cows more efficiently convert feeds to production over late cut silage (p=0.016) (Table 8) and the earlier authors Cabezas-Garcia et al.^25,26 also approve similarly, early cut silage fed cows more efficiently covert feed to production than late cut silage. Generally, the result with previous findings confirm that early cut silage had significant effect on milk yield and feed efficiency but milk composition and DMI was not significantly differed.^27-29 So that, with the significant result of feed conversion efficiency and milk yield; the result confirms and encourages farmers to switch off using late harvest silage for increasing dairy cows’ productivity with efficient use of feed resources.

Corn and alfalfa silage

The result of CS and AS comparison fed cows were not display any significant difference on DMI, milk yield and milk composition. similarly, previous findings confirm that CS and AS diet was not significantly varied on cows DMI, milk yield and fat composition.^30,31 Although crude protein content of alfalfa silage diet was higher but total dry matter digestibility was not differed among diets this may be a reason that diets not differed in cow’s productivity. On the other hand, earlier finding showed that replacement DMI of AS with CS significantly decreases (p<0.01).³² The reason of increment of DMI of AS probably due to its higher NDF digestibility.^33-35 The depression of CS DMI related with the enclosure of high moisture content in the diet.³⁶ Milk yield was higher on AS over CS (P=0.02).^32,35 In contrary, milk yield was higher on CS than AS.^37-39 The result generally confirms; even though there was a difference between diets for cows DMI, milk yield and composition but it was not significantly observed. Feed efficiency was not affected by forage types so feeding of these both comparison diets didn’t affect cows feed intake and milk productivity.

Sorghum and corn silage

When we compare SS and CS-based diets the result shows that DMI of SS was significantly lower than CS (P=0.04). Similarly, the previous authors also confirm that, in the replacement of CS by SS percentage increment of SS significantly decreases DMI.^40-42 This increment was probably the particle size of SS.⁴² The less digestibility of SS over CS was also other possible reason for decrement of DMI.⁴³ Other previous authors stated in different way, there was a stable similar association of DMI between CS and SS fed lactating cows.^44-46 On the result milk yield of CS fed cows display significantly higher milk yield over SS fed cows (P=0.02) and this earlier authors observed similarly.^40,47-49 On the other hand, similar with the result previous findings deep-rooted the non-significancy of milk composition between the diet.^41,45,47-50 Conclusively, on the result there was a significant difference of milk yield and feed intake between CS and SS diet fed cows but feed efficiency between the diet was not significantly differed. So that the present result confirms that replacing CS with SS didn’t affect productivity and the previous findings also strongly confirm for the replacement of these diets.^41,50

Silage and hay

For silage and hay fed cows comparison their DMI, MY and milk composition were not significantly varied. The earlier authors similarly stated that Silage and hay based prepared forage of gama grass, cowpea and alfalfa was observed with no significance difference on lactating cows DMI, MY and composition.^30,51-54 On the other hand, DMI and MY of Silage was higher than hay the reason probably silage diet digestibility was higher than hay as hay had higher NDF content and less digestible due to its leaf loss during hay making.^18,19,55-57  

Feed efficiency of lactating cows was lower on hay fed cows than silage which means silage fed cows were efficiently convert feed to production but not significantly differed.^51,54,58 In combining with the collective data set the present meta-analysis confirms that feed efficiency was not significantly differed. Some feed technologies like processed (Cubed and chopped forages) of both hay and silage can be used as an alternative feed for replacement diet. Although processing of hay or silage shows similar results in which it decreases DMI and MY with less chewing time. Processed forages has insufficient effective fiber so that minimum amount of unprocessed hay or silage should be included as forage particle length is critical to maintain ruminal function.⁵¹ Most importantly DMI decreases when NDF content of diets exceeded 25%.⁵⁹

Legume and grass silage

The comparison of legume silage fed cows displays significantly higher milk yield and DMI over grass silage; whereas for milk composition protein content was significantly higher for grass-based diet but no significance difference was observed on fat content. Correspondingly, earlier authors approves that both alfalfa and Red clover legume silage was significantly higher on DMI and milk yield over grass silage.^5,22,60-64 The reason probably legume silage was more digestible than grass silage.⁶³  

On the other hand, the previous findings displays with no significant difference between Red clover legume silage and grass silage in both milk yield and Composition^65,66 and also this authors^5,58 states Similarly, in that milk composition of alfalfa silage and grass silage was not significantly differed. We Usually think that grass silage fed cows results in lower milk yield and DMI than legume silage; but orchard grass silage and alfalfa silage fed cows didn’t show any significance difference in both milk yield and DMI. The reason was probably harvesting time of grass Silage.^28,67

According to Moorby et al.⁶⁸ feed efficiency was higher for normal grass silage over Red clover legume silage, and authors Broderick et al.⁶⁰ and Fisher, et al.⁶¹ states similarly, for Ryegrass silage feed efficiency was higher than alfalfa legume silage. Generally, although legume silage was observed high significant difference on milk yield and DMI over grass-based fed diet but feed efficiency was not significantly differed. So that the present result concludes grass silage can be replaced by legume silage with better forage management.

This meta-analysis was analyzed six sub-grouped dairy feed comparisons in the aim of determining effects of various feed on lactating cows feed intake and productivity. For maturity-based comparisons feeding either early or late alfalfa hay has no effect on DMI and milk productivity of lactating cows. Alfalfa hay maturity didn’t show any significant difference on feed intake and lactating cows’ productivity as a whole. The comparisons of cows fed corn silage over sorghum silage; legume silage over grass silage show a high significant difference for both DMI and milk yield but feed efficiency was not significantly differed with in these comparison feed types. On the other hand, silage maturity shows high significant variation for early cut silage over late cut on milk yield and feed efficiency. Whereas alfalfa versus corn; grass versus hay-based comparisons didn’t show any significant different for cows’ feed intake and productivity.

Generally, for almost all comparisons feeding either comparison feeds didn’t affect feed intake and cow’s productivity except silage maturity; for silage maturity this meta-analysis confirms that to increase lactating cow’s productivity farmers highly encouraged to switch off using late harvest silage as early cut silage more efficiently converts feed to production than late cut silage and also results significantly higher milk yield but for others feed efficiency was not significantly differed.

The authors have not declared any conflict of interests.

First of all, I would like to praise and exalt Almighty God for giving me courage and strength in going to succeed with the people who have invested their knowledge for my new era of success. I would like to express my warmest recognition to my supervisor professor Hou Yong for all his patience help in spending their precious time to give earnest and regular advice, and to make this manuscript directional and successfully ended.

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